JMIR J Med Internet Res Journal of Medical Internet Research 1438-8871 JMIR Publications Toronto, Canada v24i10e40488 36264607 10.2196/40488 Original Paper Original Paper The Efficacy of a Web-Based Stress Management Intervention for Employees Experiencing Adverse Working Conditions and Occupational Self-efficacy as a Mediator: Randomized Controlled Trial Leung Tiffany Stratton Elizabeth Nixon Patricia MSc 1 https://orcid.org/0000-0002-9747-3845 Ebert David Daniel PhD 2 https://orcid.org/0000-0001-6820-0146 Boß Leif PhD 1 https://orcid.org/0000-0001-9012-0839 Angerer Peter PhD 3 https://orcid.org/0000-0002-9602-7405 Dragano Nico PhD 4 https://orcid.org/0000-0002-0378-0757 Lehr Dirk PhD 1
Department of Health Psychology and Applied Biological Psychology Institute of Psychology Leuphana University Universitätsallee 1 Lueneburg, 21335 Germany 49 41316772720 lehr@leuphana.de
https://orcid.org/0000-0002-5560-3605 Department of Health Psychology and Applied Biological Psychology Institute of Psychology Leuphana University Lueneburg Germany Division of Psychology & Digital Mental Health Care Department for Sport & Health Sciences Technical University of Munich Munich Germany Faculty of Medicine Institute of Occupational, Social and Environmental Medicine Centre for Health and Society, Heinrich Heine University Duesseldorf Germany Institute of Medical Sociology Centre for Health and Society University Hospital Duesseldorf Germany Corresponding Author: Dirk Lehr lehr@leuphana.de 10 2022 20 10 2022 24 10 e40488 23 6 2022 21 7 2022 11 8 2022 24 8 2022 ©Patricia Nixon, David Daniel Ebert, Leif Boß, Peter Angerer, Nico Dragano, Dirk Lehr. Originally published in the Journal of Medical Internet Research (https://www.jmir.org), 20.10.2022. 2022

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 Background

Work stress is highly prevalent and puts employees at risk for adverse health consequences. Web-based stress management interventions (SMIs) promoting occupational self-efficacy might be a feasible approach to aid employees to alleviate this burden and to enable them to improve an unbalanced situation between efforts and rewards at work.

 Objective

The first aim of this randomized controlled trial was to investigate the efficacy of a web-based SMI for employees perceiving elevated stress levels and an effort-reward imbalance in comparison to a waitlist control (WLC) group. Second, we investigated whether the efficacy of an SMI could be explained by an increase in occupational self-efficacy and whether this personal resource enables employees to change adverse working conditions.

 Methods

A total of 262 employees reporting effort-reward imbalance scores over 0.715 and elevated stress levels (10-item Perceived Stress Scale [PSS-10] score ≥22) were randomly assigned to either the intervention group (IG; SMI) or the WLC group. The primary outcome was perceived stress measured using the PSS-10. The secondary outcomes included mental and work-related health measures. Four different mediation analyses were conducted with occupational self-efficacy, efforts, and rewards as mediators. After eligibility screening, data were collected web based at baseline (T1), 7 weeks (T2) and 6 months (T3).

 Results

Study participation was completed by 80% (105/130, 80.8%) in the IG and 90% (119/132, 90.2%) in the WLC group. Analyses of covariance revealed that stress reduction was significantly higher for the SMI group compared with the WLC group at T2 (d=0.87, 95% CI 0.61-1.12, P<.001) and T3 (d=0.65, 95% CI 0.41-0.90, P<.001). Mediation analyses indicated that occupational self-efficacy mediated the beneficial effect of the SMI on stress directly. Furthermore, the analyses revealed a significant indirect effect of occupational self-efficacy via rewards (b=0.18, t259=4.52, P<.001), but not via efforts (b=0.01, t259=0.27, P>.05) while efforts still had a negative impact on stress (b=0.46, t257=2.32, P<.05).

 Conclusions

The SMI was effective in reducing stress and improving occupational self-efficacy in employees despite them experiencing an effort-reward imbalance at work. Results from mediation analyses suggest that fostering personal resources such as occupational self-efficacy contributes to the efficacy of the SMI and enables employees to achieve positive changes regarding the rewarding aspects of the workplace. However, the SMI seemed to neither directly nor indirectly impact efforts, suggesting that person-focused interventions might not be sufficient and need to be complemented by organizational-focused interventions to comprehensively improve mental health in employees facing adverse working conditions.

 Trial Registration

German Clinical Trials Register DRKS00005990; https://tinyurl.com/23fmzfu3

 occupational eMental health stress occupational self-efficacy effort-reward imbalance randomized controlled trial Introduction

More than a decade ago, the World Health Organization identified stress as major risk factor for adverse consequences on physical and mental health for the 21st century [1]. In particular, the workplace can be a source of stress that can be associated with an increased risk of depression and cardiovascular diseases [2-4]. Next to such harmful effects on employees’ personal lives and health, experiencing high strain at work can entail substantial societal costs [5].

One of the most prominent theoretical frameworks to investigate workplace stressors is the effort-reward imbalance model [6]. In short, this model is based on the premise of an imbalance between efforts invested and low rewards received in return. Both efforts and rewards therefore reflect subjectively perceived working conditions employees are exposed to. Rewards can be distinguished between financial payments, job security, or career prospects, and intangible compensation such as esteem or praise. During the past few decades, the model was well researched. It was shown that employees experiencing an effort-reward imbalance have an increased risk of depression [7], lower immunity [8], or coronary heart disease [9]. Multiple systematic reviews demonstrated robust evidence for the links between an effort-reward imbalance and health, and suggested that it can instigate psychological, physical, and behavioral health–impairing pathways [10-12].

Psychosocial hazards were identified as one of the key emerging health risks [13] and there were significant developments to address psychosocial risk factors at work. For example, the National Standard of Canada for Psychological Health and Safety in the Workplaces provides a comprehensive framework for an approach to ensure a psychologically healthy workplace [14]. Notably, changing adverse working conditions requires a timely and complex transformational process that can be a considerable source of work stress itself and is associated with different risks such as an increase of stress-related medication intake [15].

Workers already affected by high levels of stress are in an acute need of relief, and so waiting for the successful implementation of organizational changes can be challenging. In this situation, a stress management intervention (SMI) might be a first step to support those in need of help sooner [16]. There is evidence for the beneficial effects of SMIs in traditional face-to-face settings [17], which was complemented by a more recent and growing body of research for the web-based delivery [16,18,19]. Web-based interventions allow the workforce to benefit from low-threshold access and highly flexible participation in terms of time and location, and employers to profit from easy scalability and low required resources [20]. Furthermore, they might have the potential to alleviate the burden of workplace stressors by promoting self-efficacy and improving various health outcomes such as insomnia or depression [21-24] in both short and long term [25,26]. However, until today, evidence is missing on whether a web-based SMI could also effectively reduce perceived stress in employees who are exposed to adverse working conditions in terms of an imbalance between efforts and rewards. Moreover, no trial has yet examined mechanisms of change within this high-risk population and whether an increase in personal resources could enable employees to improve the unbalanced situation between efforts and rewards at work.

An effective implementation of a web-based SMI for employees who are exposed to adverse working conditions could be a person-centered intervention helping workers to initiate changes, a strategy known as problem-focused coping following the transactional model by Lazarus and Folkman [27]. A necessary personal resource for self-initiated changes employees make to redesign working conditions is self-efficacy, which is believed to trigger proactive behaviors undertaken at work [28]. Initially, Bandura [29] defined self-efficacy as confidence to meet difficult challenges or prospective problems by oneself. Individuals with high self-efficacy experience lower levels of work strain and engage more in problem-focused coping [30]. Another study confirmed that a problem-solving training for teachers could strengthen the ability to cope with problems and stressful situations as well as increase self-efficacy [31]. Within this organizational context, occupational self-efficacy can be described as personal belief in work-related abilities [32]. Studies on occupational self-efficacy have demonstrated positive associations with job performance, employee satisfaction, employability, and work commitment, and negative relationships with job insecurity [32,33]. A study on the same SMI that was examined in this randomized controlled trial (RCT) provided first evidence for effects on occupational self-efficacy [34], while the previously stated need for research on self-efficacy as a mechanism of change in an occupational SMI has not been addressed yet [35]. Moreover, there is no evidence on the effects of occupational self-efficacy on the perception of adverse working conditions yet despite the assumption that self-efficacy as a function of self-regulation conducive to health relies on successful exchange of efforts and rewards [36].

To the best of our knowledge, this is the first RCT to investigate the efficacy of a web-based occupational SMI in employees perceiving high stress levels and an effort-reward imbalance and to explore mediating effects of occupational self-efficacy, efforts, and rewards on stress reduction. This trial will examine the hypothesis that the SMI will effectively reduce perceived stress in the intervention group (IG) compared with a waitlist control (WLC) group. The second study aim is to investigate mediating effects of the personal resource of occupational self-efficacy and environmental factors, specifically efforts, and rewards at the workplace in the association between the intervention and perceived stress.

 Methods Study Design and Conditions

A primary RCT including 264 participants experiencing an effort-reward imbalance was conducted in compliance with the Declaration of Helsinki and Good Clinical Practice and following the CONSORT (Consolidated Standards of Reporting Trials) guidelines [37,38] (Multimedia Appendix 1). Based on meta-analytic evidence for web-based SMI revealing moderate effects (Hedges g=0.54) [19] and considering the impact of adverse working conditions, this study aimed to detect differences between groups with an effect size of Cohen d=0.35 based on a power (1–β) of 0.80 in a 2-tailed test with α=.05. Participants were randomly assigned to the IG or the WLC group at a ratio of 1:1 using an automated computer-based random integer generator (DatInf RandList; Datinf GmbH). Participants were allocated to the study groups by an independent researcher not otherwise involved in the study. Self-reported outcomes were assessed between May 2014 and May 2015 with a secured online-based self-report system (AES; 256-bit encrypted) at screening for eligibility (T0), baseline (T1), and 7 weeks (T2), and 6 months (T3) after randomization. After allocation, participants in the IG received immediate access to the intervention, whereas those in the WLC group obtained access after 6 months. Treatment as usual was not restricted and monitored. None of the obtained data presented here were published before.

 Participants and Recruitment

Participants were recruited from the general working population via the research project website and mass media (eg, articles in health insurance magazines). Inclusion criteria were the willingness to give informed consent; legal age (18 years); employment; 10-item Perceived Stress Scale (PSS-10) [39,40] score ≥22; effort-reward imbalance [41] score >0.715, which was found to indicate a highly hazardous imbalance between effort and rewards at the workplace [42]; no notable suicidal risk, as indicated by a score of >1 on item 9 (I feel I would be better off dead) of the Beck Depression Inventory [43]; and no previous or current diagnosis of dissociative symptoms or psychosis. Interested participants signed up on the open access website with their email address to receive a link to the eligibility screening questionnaire. Eligible applicants were required to provide informed consent and baseline data (T1).

 Intervention

Psychologists developed the intervention for employees based on Lazarus’ transactional model of stress focusing on problem solving and emotion regulation skills [27]. The intervention encouraged participants to reflect on meaningful issues that were not restricted to either work or personal life. The efficacy was demonstrated before in an indicated prevention sample and with different guidance formats, namely, adherence-focused guidance and self-help [22,44,45]. The SMI consisted of 7 core modules and an optional booster session 4 weeks after termination. Module completion required 45-60 minutes and participants were advised to complete at least one per week, adding up to an intervention period of 4-7 weeks. Participants could choose whether and how often they preferred to receive short automatic motivational SMS text messages to their mobile device (infrequent or intensive, ie, 1-3 SMS text messages daily). In addition, participants could inquire feedback-on-demand, which was provided by an e-coach within 48 hours only upon request on the internal messaging platform. E-coaches were skilled psychologists following feedback guidelines from the standardized manual for the intervention. Participants were assigned to an e-coach in a 1-to-1 ratio.

 Primary Outcome Measure

The primary outcome was perceived stress appraised with the German version of PSS-10 [39,40], which was also developed based on Lazarus’ transactional model of stress. The items assess to what extent participants experienced their lives as stressful within the past week on a 5-point Likert scale from 0 (never) to 4 (very often), resulting in sums from 0 to 40, with higher scores reflecting higher levels of stress. In this study, values for the internal reliability (Cronbach α) were .81 at T1, .89 at T2, and .92 at T3.

 Secondary Outcome Measures

Included measures for the secondary outcomes are listed in the following sections, with number of items, item range, and reliabilities assessed at T2.

Mediators

Among the secondary outcomes, 2 measures were assessed for the inclusion as mediators. First, the Effort Reward Imbalance Questionnaire Short Form [41] with the subscales efforts (3 items; α=.78) and rewards (7 items; α=.79; score range 1-4). And second, the short form of the Occupational Self-Efficacy Scale (OSS-SF [32]; 6 items; α=.89; score range 1-6).

 Work-Related Health

The subscale emotional exhaustion of the Maslach Burnout Inventory (MBI-GS-D; 5 items; α=.87; score range 1-6) was used to evaluate work-related health [46]. The Utrecht Working Scale (UWES) [47] was used to examine work engagement (9 items; α=.93; score range 0-6). A single-item question was used to assess work ability (Work Ability Index) [48] and the Work Limitations Questionnaire [49] was administered to examine presenteeism.

 Mental Health

The short version of the Centre for Epidemiological Studies’ Depression scale (CES-D) [50,51] was used to assess depression (15 items; α=.84; score range 0-3). The Connor-Davidson Resilience Scale [52] was used to examine resilience (10 items; α=.88; score range 0-4). The Assessment of Quality of Life (AQoL)-8D Multi-Attribute Utility Instrument [53] was used to examine health-related quality of life (35 items, different ranges from 1 to 5 and 1 to 6; α=.96) at T3.

 Other Measures

To assess the level of satisfaction with the intervention, the Client Satisfaction Questionnaire adapted to web-based interventions was used (CSQ-I; 8 items; α=.92; score range 1-4) [54]. In addition, self-developed measures were used to assess demographics, current occupation, work sector, income, educational level, and previous use of health services.

 Statistical Analyses

Statistical analyses were performed according to the recommendations of the CONSORT statement [37]. Data were analyzed with SPSS Statistics version 25 (IBM Corp.) [55] based on the intention-to-treat principle. An additional per-protocol analysis was conducted for the primary outcome, including only participants who completed at least six modules. Analyses of covariance (ANCOVA) were calculated with outcome baseline scores as covariates and a 2-tailed significance level at P<.05 to detect between-group differences for the IG and the WLC group at T2 and T3. Simulation studies have already demonstrated the methodological robustness of ANCOVA against bias, higher precision, and statistical power for experimental studies [56,57]. To handle missing data, multiple imputations were conducted for the intention-to-treat and per-protocol analyses with 10 estimates for each value that were aggregated into an overall value [58].

 Response Analyses

The Reliable Change Index of Jacobson and Truax [59] was used to investigate improvements of the primary outcome on an individual level. The SD of 6.2 and the reliability of PSS-10 of the norm population [60] were used in the formula [1.96 × SD1 × sqrt(2) × sqrt(1–rel)] to calculate that a reduction in perceived stress could be defined as reliably improved if changes of more than ±5.16 points were detected from T1 to T2. Symptom-free status was achieved according to Jacobson and Truax [59] when participants scored more than 2 SDs below the baseline mean (T1) of the primary outcome in the IG (mean 23.76, SD 5.11). The number needed to treat and 95% CI were calculated to indicate the average number of participants who need to be treated to achieve an additional response compared with the control group [61].

 Mediation Analyses

Four mediation analyses were conducted using the PROCESS macro (version 4.0) for SPSS [62]. The models build up on each other to explore their individual and shared contribution in stress reduction. In all models, the independent variable (X) was the study condition, and the dependent variable (Y) was perceived stress (PSS-10 at T3). The proposed mediators were occupational self-efficacy at T2 (PROCESS model 4); occupational self-efficacy at T2 and efforts at T3 (PROCESS model 6); occupational self-efficacy at T2 and rewards at T3 (PROCESS model 6); and occupational self-efficacy, efforts, and rewards at T3 (PROCESS model 81). Baseline scores of the outcome and mediator were considered covariates. For indirect effects that were considered significant if P<.05 and 95% CIs did not cover 0, 10,000 bias-corrected bootstrap samples were applied [62]. An additional sensitivity analysis including only study completers was performed.

 Ethics Approval

The Ethical Committee of the Leuphana University of Lueneburg approved the study (reference Ebert201408_Stresstraining). The trial was registered in the German Clinical Trials Register (DRKS00005990).

 Results Participants and Baseline Characteristics

The sample initially consisted of 264 participants of which 2 requested the deletion of assessed data after trial conduction. Consequently, the final sample included 262 participants (182/262, 69.4% female) aged 20-65 years (mean 42.2 years, SD 9.76 years), allocated to either the IG (n=130) or the WLC (n=132) group. Figure 1 depicts the study flow and Table 1 summarizes detailed baseline characteristics. A multivariate ANOVA indicated there was no meaningful difference in baseline outcomes between groups (F19,232=1.08, P=.37). Primary outcome data were missing for 9.9% (n=26) at T2 and 15.3% (n=40) at T3. The Little missing completely at random test failed significance, indicating that the null hypothesis proposing patterns of missing values being not dependent on observed and unobserved factors among the participants’ values need not be rejected.

Participant flow.

Baseline characteristicsa.

Characteristics All participants (N=262) IGb (n=130) WLCc group (n=132)
Sociodemographic
Age, mean (SD) 42.20 (9.76) 42.87 (9.54) 43.42 (10.02)
Men, n (%) 80 (30.5) 45 (34.60) 35 (26.5)
Women, n (%) 182 (69.5) 85 (65.40) 97 (73.5)
Diverse, n (%) N/Ad N/A N/A
Marital status, n (%)
Single 78 (29.8) 41 (31.5) 37 (28.0)
Married 123 (46.9) 59 (45.4) 64 (48.5)
Cohabited 29 (11.1) 16 (12.3) 13 (9.8)
Divorced 31 (11.8) 14 (10.8) 17 (12.9)
Widowed 1 (0.4) N/A 1 (0.8)
Educational level, n (%)
Low 6 (2.3) 2 (1.5) 4 (3.0)
Middle 54 (20.6) 22 (16.9) 32 (24.2)
High 202 (77.1) 106 (81.5) 96 (72.7)
Employment
Full-time, n (%) 205 (78.2) 105 (80.8) 100 (75.8)
Part-time, n (%) 53 (20.2) 23 (17.7) 30 (22.7)
Sick leave, n (%) 4 (1.5) 2 (1.5) 2 (1.5)
Managerial position, n (%) 100 (38.2) 50 (38.5) 50 (37.9)
Work experience in years, mean (SD) 18.40 (10.83) 17.79 (10.86) 19.01 (10.81)
Work sectors, n (%)
Service 62 (23.7) 26 (20) 36 (27.3)
Economy 56 (21.4) 22 (16.9) 34 (25.8)
Health 33 (12.6) 22 (16.9) 11 (8.3)
Social 44 (16.8) 19 (14.6) 25 (18.9)
Information technologies 24 (9.2) 15 (11.5) 9 (6.8)
Other 36 (13.7) 19 (14.6) 17 (12.9)
Income, n (%)
Low 73 (27.9) 29 (22.3) 44 (33.3)
Middle 45 (17.2) 26 (20) 19 (14.4)
High 123 (46.9) 64 (49.2) 59 (44.7)
Use of health services, n (%)
Previous or current psychotherapy 119 (45.4) 55 (42.3) 64 (48.5)
Experience in health trainings 38 (14.5) 15 (11.5) 23 (17.4)

aValues presented only for participants who provided the respective data.

bIG: intervention group.

cWLC: waitlist control.

dN/A: not applicable.

 Primary Outcome Measure

ANCOVAs to detect differences between the IG and the WLC group at T2 and T3 revealed significantly lower stress levels assessed with the PSS-10 for the IG at T2 (F259,1=46.14, P<.001, d=0.87, 95% CI 0.61-1.12, Δ5.00) and T3 (F259,1=24.82, P<.001, d=0.65, 95% CI 0.41-0.90, Δ4.19). The per-protocol analysis corroborated those results with significant between-group differences at T2 (F173,2=34.86, P<.001, d=1.04, 95% CI 0.69-1.40, Δ5.79) and T3 (F173,2=20.15, P<.001, d=0.56, 95% CI 0.22-0.90, Δ3.68). For all outcome measures at T2 and T3, Table 2 displays the means and SDs and Table 3 shows ANCOVA results.

Means and SDs of outcome variables at baseline (T1), 7 weeks (T2), and 6 months (T3) after the intervention.

Outcome T1 T2a T3a
IGb WLCc IG WLC IG WLC
Primary outcome measure
Perceived stress 23.76 (5.11) 24.81 (5.03) 18.33 (6.18) 23.33 (5.32) 17.53 (6.42) 21.72 (6.39)
Perceived stress (per-protocol analysis) 23.89 (5.63) 24.79 (5.04) 17.5 (6.14) 23.29 (5.32) 18 (6.97) 21.68 (6.39)
Secondary outcome measures
Mental health and work related
Quality of life 0.58 (0.15) 0.55 (0.13) N/Ad N/A 0.68 (0.17) 0.57 (0.17)
Depression 17.05 (6.09) 18.05 (6.43) 13.68 (7.41) 15.76 (7.43) 11.56 (6.74) 14.8 (8.46)
Resilience 20.12 (6.67) 20.29 (6.37) 22.5 (6.08) 19.38 (6.12) N/A N/A
Emotional exhaustion 4.57 (0.78) 4.62 (0.73) 4.05 (0.89) 4.52 (0.81) 3.87 (0.94) 4.42 (0.95)
Occupational self-efficacy 22.06 (6.14) 21.58 (6.24) 24.38 (5.41) 22.2 (6.08) N/A N/A
Work engagement (vigor) 2.95 (1.21) 2.99 (1.18) 3.06 (1.17) 2.72 (1.15) 3.1 (1.18) 2.75 (1.21)
Work engagement (dedication) 3.31 (1.3) 3.28 (1.37) 3.36 (1.17) 2.98 (1.36) 3.37 (1.27) 3.02 (1.3)
Work engagement (absorption) 3.01 (1.39) 3.01 (1.51) 3.14 (1.28) 2.84 (1.38) 3.14 (1.27) 2.85 (1.38)
Work ability index 5.92 (1.96) 5.86 (1.96) 6.55 (1.88) 5.83 (2.08) N/A N/A
Presenteeism 5.01 (2.25) 5.27 (2.58) 4.5 (2.37) 4.94 (2.39) N/A N/A
Effort-reward imbalance
Efforts 10.67 (1.42) 10.5 (1.52) 10.01 (1.76) 10.11 (1.76) 9.72 (1.76) 9.89 (1.83)
Rewards 16.29 (3.74) 15.77 (3.86) 16.69 (3.8) 15.61 (3.96) 17.06 (3.62) 16.03 (3.9)
Ratio 1.62 (0.49) 1.64 (0.49) 1.5 (0.55) 1.62 (0.56) 1.43 (0.47) 1.55 (0.54)

aMissing data handled by multiple imputation.

bIG: intervention group.

cWLC: waitlist control.

dN/A: not applicable.

Between-group differences at 7 weeks (T2) and 6 months (T3) after the intervention.

Outcomes T2a T3a
d (95% CI) ANCOVAb (F259,1) d (95% CI) ANCOVA (F259,1)
Primary outcome measure
Perceived stress 0.87 (0.61 to 1.12) 46.14c 0.65 (0.41 to 0.90) 24.82c
Perceived stress (per-protocol analysis)d 1.04 (0.69 to 1.40) 34.86c 0.56 (0.22 to 0.90) 20.15c
Secondary outcome measures
Mental health and work related
Quality of lifee N/Af N/A 0.65 (0.37 to 0.93) 14.44c
Depression 0.28 (–0.04 to 0.52) 3.55 0.42 (0.18 to 0.67) 9.99g
Resilience N/A N/A 0.51 (0.26 to 0.76) 31.72c
Emotional exhaustion 0.56 (0.31 to 0.80) 25.36c 0.59 (0.34 to 0.83) 25.79c
Occupational self-efficacy 0.38 (0.13 to 0.62) 10.65g N/A N/A
Work engagement (vigor) 0.29 (0.05 to 0.53) 9.30g 0.29 (0.05 to 0.53) 7.61g
Work engagement (dedication) 0.30 (0.06 to 0.54) 8.71g 0.27 (0.03 to 0.52) 6.22h
Work engagement (absorption) 0.41 (0.66 to 0.17) 5.80h 0.22 (0.03 to 0.46) 3.97h
Presenteeism 0.18 (–0.06 to 0.43) 1.61 N/A N/A
Work ability index 0.36 (0.12 to 0.60) 9.19g N/A N/A
Effort-reward imbalance
Efforts 0.05 (–0.19 to 0.30) 1.72 0.09 (–0.15 to 0.34) 1.87
Rewards 0.28 (0.04 to 0.52) 4.42h 0.27 (–0.03 to 0.52) 3.72
Ratio 0.22 (0.03 to 0.50) 4.21h 0.24 (0.01 to 0.48) 4.07h

aMissing data handled by multiple imputation.

bANCOVA: analysis of covariance

cSignificance level used: P<.001.

dF173,2.

eF200,1.

fN/A: not applicable.

gSignificance level used: P<.01.

hSignificance level used: P<.05.

 Response Analyses

At T2, significantly more participants in the IG (65/130, 50%) showed a reliable improvement in perceived stress measured with the PSS-10 compared with the WLC group (33/132, 25%) and significantly fewer participants in the IG (4/130, 3.1%) experienced symptom deterioration compared with the WLC group (14/132, 10.6%; χ22=19.94, P<.001). The number needed to treat to achieve reliable improvement was 4 (95% CI 2.8-7.3). The number of symptom-free participants at T2 was significantly higher in the IG (39/130, 30%) compared with the WLC group (7/132, 5.3%; χ21=23.52, P<.001).

 Secondary Outcome Measures

The ANCOVAs showed significant between-group differences for most secondary outcome measures (Table 3). Positive impacts for participants in the IG compared with the WLC group were found at T2 and T3 for occupational self-efficacy (measured with the OSS-SF), burnout (assessed with the MBI-GS-D), work engagement (assessed with the UWES), and work ability (Work Ability Index). Effect sizes (d) ranged from 0.29 (95% CI 0.05-0.53; UWES scale vigor) to 0.56 (95% CI 0.31-0.80; MBI-GS-D) at T2 and from 0.22 (95% CI 0.03-0.46; UWES scale absorption) to 0.65 (95% CI 0.37-0.93; AQoL) at T3. Scores between groups did not significantly differ for depression (CES-D; d=0.28, 95% CI –0.04 to 0.52, P=.06) and work limitations (Work Limitations Questionnaire; d=0.18, 95% CI –0.06 to 0.43, P=.21) at T2. Regarding the effort-reward imbalance, participants in the IG showed significantly higher values for rewards at T2 (d=0.28, 95% CI 0.04-0.52, P=.04), whereas between-group scores did not significantly differ for efforts at T2 (d=0.05, 95% CI –0.19 to 0.30, P=.19) and T3 (d=0.09, 95% CI –0.15 to 0.34, P=.17), and for rewards at T3 (d=0.27, 95% CI –0.03 to 0.52, P=.06).

 Mediation Analyses

Figure 2 depicts the 4 mediation analyses performed. Results of the first model (Figure 2A) showed that the unstandardized regression coefficient for the study groups (X) predicting stress (Y) was significant (c=–4.19, t260=–5.29, P<.001). Occupational self-efficacy (M) was found to be a significant mediator for this effect (b=–0.44, t258=–6.87, P<.001). Furthermore, the study group had a significant effect on occupational self-efficacy (b=2.18, t260=3.06, P<.002). The direct effect remained significant after incorporating the mediating variable into the model (c′=–3.23, t260=–4.36, P<.001). The indirect effect was significant (b=0.95, 95% CI –1.73 to –0.32, P<.001). This model accounted for 24% of the variance (R2) in stress reduction.

The second mediation model (Figure 2B) with occupational self-efficacy as M1 and efforts as M2 revealed significant total (c=–4.19, t260=–5.29, P<.001) and direct (c′=–3.14, t260=–4.36, P<.001) effects. Occupational self-efficacy (M1) significantly mediated the effect on stress (b=–0.44, t258=–6.59, P<.001), whereas it had no significant effect on efforts (M2; b=0.01, t259=0.27, P=.79). However, efforts (M2) were significantly associated with stress (b=0.53, t258=2.64, P=.008). The study group had no significant effect on efforts (M2; b=–0.18, t258=–0.79, P=.43). Therefore, a significant indirect mediating effect was only found for the association of occupational self-efficacy with the study group (b=–0.14, 95% CI –0.25 to –0.05, P<.001). Together, 26% of the variance (R2) in perceived stress was explained.

After incorporating occupational self-efficacy as M1 and rewards as M2, the mediation model (Figure 2C) resulted in significant total (c=–4.19, t260=–5.29, P<.001) and direct (c′=–3.00, t260=–4.12, P<.001) effects. Occupational self-efficacy (M1) significantly mediated the effect on stress (b=–0.37, t258=–5.76, P<.001) and rewards (M2; b=0.18, t259=4.52, P<.001). Rewards (M2) could significantly predict stress (b=–0.37, t258=–3.79, P<.001). Comparable to the preceding mediation model, a significant indirect mediation effect for the association between the intervention and stress as an outcome could be found for occupational self-efficacy (b=–0.12, 95% CI –0.22 to –0.04, P<.001). Furthermore, the indirect path taking occupational self-efficacy (M1) and rewards (M2) between the study group and perceived stress into account was significant (b=–0.02, 95% CI –0.05 to –0.01, P<.001). Participation in the intervention did not significantly predict rewards (M2; P=.16). In total, all variables accounted for R2=0.28.

The fourth mediation model (Figure 2D) that incorporated all mediators (M1: occupational self-efficacy, M2: efforts, and M3: rewards) again resulted in significant total (c=–4.19, t260=–5.29, P<.001) and direct (c′=–2.93, t260=–4.06, P<.001) effects. Occupational self-efficacy (M1) significantly predicted perceived stress (b=–0.38, t257=–5.91, P<.001) and rewards (M3) (b=0.18, t259=4.52, P<.001), yet not efforts (M2; b=0.01, t259=0.27, P=.79). The effect on stress was also significantly predicted by both efforts (M2; b=0.46, t257=2.32, P=.02) and rewards (M3; b=–0.35, t257=–3.56, P<.001). The study group did not significantly predict neither efforts (M2) nor rewards (M3) directly. Altogether, significant indirect paths between the study group and perceived stress were found for occupational self-efficacy (M1; b=–0.12, 95% CI –0.22 to –0.04, P<.001) as well as for occupational self-efficacy (M1) and rewards (M3; b=–0.02, 95% CI –0.05 to –0.01, P<.001). This final model including all proposed mediators together explained 29% of the variance (R2) in stress reduction. For all models, sensitivity analyses performed including only study completers corroborated the results.

Mediation analyses with study condition as independent variable (X) and perceived stress (PSS-10) at T3 as dependent variable (Y) for all models. Proposed mediators: (A) Occupational self-efficacy at T2; (B) Occupational self-efficacy at T2 and efforts at T3; (C) Occupational self-efficacy at T2 and rewards at T3; and (D) Occupational self-efficacy at T2, and efforts and rewards at T3. Study conditions are coded 0=wait list control group, 1=intervention group. The figure includes unstandardized β coefficients and illustrates significant (solid line) and non-significant (dotted line) effects between variables, total (c) and direct (c′) effects. Significance levels used: ***P<.001, **P<.01, *P<.05.

 Discussion Principal Findings

Results of this study confirm that the SMI could effectively reduce stress in employees perceiving elevated stress levels and even when they were exposed to a high load of efforts that is not adequately balanced by rewards. Secondary analyses demonstrated the beneficial effects for mental health and work-related outcomes as well as for rewards. Step-by-step mediation analyses revealed that the participation in the intervention significantly predicted occupational self-efficacy, which describes the confidence of an individual to handle any challenges at work and which was a mediator in the effect on stress and rewards that again predicted stress. All 3 investigated mediators (ie, occupational self-efficacy, efforts, and rewards) were significantly associated with perceived stress. However, neither participation in the SMI nor the increase in occupational self-efficacy enabled employees to achieve favorable effects on the level of efforts, while efforts still enfolded an adverse effect on perceived stress.

The results revealed practically meaningful effect sizes for stress reduction. A similar effect was found in another trial on the same SMI with adherence-focused guidance [45] and our study extend those results by the inclusion of a high-risk population that experiences adverse working conditions. Compared with a study on the same SMI with more intensive guidance [22], the effect sizes were not as large at follow-up. This raises the question as to whether more personal support from a mental health expert, which is expected to be conducive to the efficacy of an SMI [19,22], might aid participants that experience greater difficulties in their stress management due to adverse working conditions. Considering the efficacy of occupational web-based interventions in general, results from this study are in line with demonstrated average effect sizes in a recent meta-analysis [19] and revealed significant improvements in a variety of outcomes on mental health and work-related levels. For example, participants in the IG showed lower levels of emotional exhaustion, more resilience, and higher work engagement, as well as vigor, dedication, and absorption at work. No significant between-group effects were found for presenteeism, while mixed results were obtained for depression. The detected effect sizes for engagement and presenteeism compare with a recent meta-analysis for occupational web-based interventions [63]. Moreover, the participation significantly increased occupational self-efficacy that was shown to be a relevant mediator in the efficacy of the SMI on stress reduction. These results support findings of another RCT on the same SMI showing significant effects on occupational self-efficacy [34] and positive associations between stress levels and self-efficacy [30]. The obtained results for the effort-reward imbalance tie well with mixed effects found in studies on the same SMI for the effort-reward imbalance ratio [34] and for efforts and rewards evaluated as separate outcomes [45], demonstrating that web-based SMIs enfold substantially larger effects on individuals’ health compared with perceived working conditions and organizational characteristics [17].

To examine whether and how an increase in personal resources could support participants in achieving successful stress reduction despite facing adverse working conditions, mediating effects were investigated not only for occupational self-efficacy, but also for efforts and rewards of the workplace. The 4 mediation analyses conducted progressively accounted for the variance in perceived stress. The first model (Figure 2A) confirmed that the participation in the intervention successfully increased occupational self-efficacy, which in turn had a significant effect on stress reduction. This is in line with evidence showing that higher levels of self-efficacy are associated with lower levels of work stress and the assumption that problem-solving skills increase the confidence of an individual to be able to proactively reduce stressors and increase rewarding situations [30]. The second mediation model (Figure 2B) showed that the intervention’s positive effect on occupational self-efficacy did not affect efforts that were negatively associated with stress. This is in line with another SMI study on teachers which showed that participants could influence rewards, yet not efforts [64]. One potential reason for the lack of association could be the design of the intervention that did not predefine the topics participants should reflect on in the problem-solving exercises and if the focus was on job-related or personal stressors. Furthermore, this portrays one of the core premises of the effort-reward imbalance model [6], that is, an increased degree of efforts necessary to spend at work is associated with high strain. The third mediation analysis (Figure 2C) revealed a significant relationship between participation in the SMI, occupational self-efficacy, and rewards. This is in line with evidence showing that occupational self-efficacy is substantially associated with affective commitment that might motivate employees to increase their job resources within their company [65]. Comparable to the precedent mediation model, rewards were significantly associated with stress, which is in line with the effort-reward imbalance model [6]. The final mediation analysis (Figure 2D) incorporated the 3 models. Occupational self-efficacy was significantly increased and a mediator in the relationship between the study group and outcome. Although both efforts and rewards predicted levels of stress, the intervention only had an impact on rewards, but not on efforts, with occupational self-efficacy seemingly playing a mediating role in this association. However, both efforts and rewards had significant effects on stress.

 Limitations

Several limitations should be considered. Despite the positive effects of the individual-focused intervention on employees’ mental health, the persisting adverse effects of efforts indicate that this approach might be incomplete. Therefore, it should be investigated whether a combination of individual- and organizational-focused digital interventions will contribute to more comprehensive effects on employees’ mental health [66]. Positive effects of occupational self-efficacy in individual-focused interventions might help employees to engage more confidently in organizational-focused interventions. Furthermore, the generalizability of the results might be limited. In contrast to recruitment on a company level, the applied open recruitment strategy addressed participants directly, which was shown to be associated with effects on personal health outcomes for occupational SMIs [19]. In this study, participants in the IG received adherence-focused guidance that was established and shown to be effective in previous studies [45,67]. Given the notion that guidance is supposed to be conducive to the efficacy of SMIs [19,68] and its low intensity in the adherence-focused format, further research could investigate whether a higher intensity in guidance might facilitate the efficacy of the SMI for participants that experience greater difficulties for successful changes due to adverse workplace conditions. Concerning the mediators, a methodological limitation might be the selection of measures in this study because participants might have been encouraged to make changes to aspects of their work that were not captured in this trial (eg, conflict between work and private life) [69]. Despite this, this trial provides valuable first insights into if and how a web-based SMI can be effective within a high-risk population despite their exposure to adverse working conditions.

 Conclusion and Practical Implications

To conclude, this trial aimed to expand research on the efficacy of web-based SMIs and to add valuable insights into the scarce evidence for high-risk populations. To the best of our knowledge, this is the first trial demonstrating positive effects of a web-based SMI on stress reduction in employees despite their adverse working conditions. In-depth analyses examining mechanisms of change suggest that the SMI increased occupational self-efficacy that mediated the intervention’s effect on stress. Furthermore, both efforts and rewards predicted levels of stress, yet the intervention only had an impact on rewards, with occupational self-efficacy seemingly playing a mediating role in this association. It seems vital to note that this web-based intervention could improve health at work within a short period and without any direct changes to working conditions. Further medium- and long-term improvements would be possible if complex organizational interventions were introduced to reduce stressors in the workplace. For practice, these results have several implications. First, the implementation of the web-based SMI can be recommended due to its beneficial health effects even if employees experience adverse working conditions. Second, occupational self-efficacy should be considered as an important concept in the design of an SMI. Third, the limited effects of the SMI on the perception of working conditions underline that organizational top-down changes are still indispensable. Future studies could further investigate which factors contribute to the efficacy of a person-centered intervention on working conditions and examine, for example, the role of guidance.

CONSORT-eHEALTH checklist (V 1.6.1).

 Abbreviations ANCOVA

analysis of covariance

 AQoL

Assessment of Quality of Life 8D Multi-Attribute Utility Instrument

 CES-D

Centre for Epidemiological Studies’ Depression Scale

 CONSORT

Consolidated Standards of Reporting Trials

 IG

intervention group

 MBI-GS-D

Maslach Burnout Inventory

 N/A

not applicable

 OSS-SF

short form of the Occupational Self-Efficacy Scale

 PSS-10

10-item Perceived Stress Scale

 RCT

randomized controlled trial

 SMI

stress management intervention

 UWES

Utrecht Work Engagement Scale

 WLC

waitlist control

 WLQ

Work Limitations Questionnaire

The German health care insurance company BARMER and the European Commission funded this study (EFRE: ZW6-80119999, CCI 2007DE161PR001).

DDE is a stakeholder in the Institute for Online Health Training that aims to transfer scientific knowledge related to this research into routine health care.

 World Health Organization (WHO) The Global Burden of Disease: 2004 Update 2008 Geneva, Switzerland WHO Niedhammer I Bertrais S Witt K Psychosocial work exposures and health outcomes: a meta-review of 72 literature reviews with meta-analysis Scand J Work Environ Health 2021 10 01 47 7 489 508 10.5271/sjweh.3968 34042163 3968 PMC8504166 Niedhammer I Sultan-Taïeb Hélène Parent-Thirion A Chastang J Update of the fractions of cardiovascular diseases and mental disorders attributable to psychosocial work factors in Europe Int Arch Occup Environ Health 2022 01 28 95 1 233 247 10.1007/s00420-021-01737-4 34181059 10.1007/s00420-021-01737-4 PMC8237556 Theorell T Hammarström Anne Aronsson G Träskman Bendz Lil Grape T Hogstedt C Marteinsdottir I Skoog I Hall C A systematic review including meta-analysis of work environment and depressive symptoms BMC Public Health 2015 08 01 15 738 10.1186/s12889-015-1954-4 26232123 10.1186/s12889-015-1954-4 PMC4522058 Hassard J Teoh KRH Visockaite G Dewe P Cox T The cost of work-related stress to society: A systematic review J Occup Health Psychol 2018 01 23 1 1 17 10.1037/ocp0000069 28358567 2017-14292-001 Siegrist J Adverse health effects of high-effort/low-reward conditions Journal of Occupational Health Psychology 1996 1 1 27 41 10.1037/1076-8998.1.1.27 Rugulies R Aust B Madsen IE Effort-reward imbalance at work and risk of depressive disorders. A systematic review and meta-analysis of prospective cohort studies Scand J Work Environ Health 2017 07 01 43 4 294 306 10.5271/sjweh.3632 28306759 3632 Eddy P Heckenberg R Wertheim EH Kent S Wright BJ A systematic review and meta-analysis of the effort-reward imbalance model of workplace stress with indicators of immune function J Psychosom Res 2016 12 91 1 8 10.1016/j.jpsychores.2016.10.003 27894456 S0022-3999(16)30420-2 Dragano N Siegrist J Nyberg ST Lunau T Fransson EI Alfredsson L Bjorner JB Borritz M Burr H Erbel R Fahlén Göran Goldberg M Hamer M Heikkilä Katriina Jöckel Karl-Heinz Knutsson A Madsen IEH Nielsen ML Nordin M Oksanen T Pejtersen JH Pentti J Rugulies R Salo P Schupp J Singh-Manoux A Steptoe A Theorell T Vahtera J Westerholm PJM Westerlund H Virtanen M Zins M Batty GD Kivimäki Mika IPD-Work consortium Effort-Reward Imbalance at Work and Incident Coronary Heart Disease: A Multicohort Study of 90,164 Individuals Epidemiology 2017 07 28 4 619 626 10.1097/EDE.0000000000000666 28570388 00001648-201707000-00022 PMC5457838 Siegrist J Li J Associations of Extrinsic and Intrinsic Components of Work Stress with Health: A Systematic Review of Evidence on the Effort-Reward Imbalance Model Int J Environ Res Public Health 2016 04 19 13 4 432 10.3390/ijerph13040432 27104548 ijerph13040432 PMC4847094 Tsutsumi A Kawakami N A review of empirical studies on the model of effort-reward imbalance at work: reducing occupational stress by implementing a new theory Soc Sci Med 2004 12 59 11 2335 59 10.1016/j.socscimed.2004.03.030 15450708 S0277953604001613 van Vegchel N de Jonge J Bosma H Schaufeli W Reviewing the effort-reward imbalance model: drawing up the balance of 45 empirical studies Soc Sci Med 2005 03 60 5 1117 31 10.1016/j.socscimed.2004.06.043 15589679 S0277-9536(04)00329-6 EU-OSHA Expert forecast on emerging psychosocial risks related to occupational safety and health. European Risk Observatory Report 2007 Luxembourg City, Luxembourg Office for Official Publications of the European Communities Canadian Standards Association, Bureau de Normalisation Psychological health and safety in the workplace ? Prevention, promotion, and guidance to staged implementation (CSA Publication No. CAN/CSAZ1003-13/BNQ9700-803/2013) 2013 Toronto, ON, Canada CSA Group and BNQ Dahl MS Organizational Change and Employee Stress Management Science 2011 02 57 2 240 256 10.1287/mnsc.1100.1273 Carolan S Harris PR Cavanagh K Improving Employee Well-Being and Effectiveness: Systematic Review and Meta-Analysis of Web-Based Psychological Interventions Delivered in the Workplace J Med Internet Res 2017 07 26 19 7 e271 10.2196/jmir.7583 28747293 v19i7e271 PMC5550734 Richardson KM Rothstein HR Effects of occupational stress management intervention programs: a meta-analysis J Occup Health Psychol 2008 01 13 1 69 93 10.1037/1076-8998.13.1.69 18211170 2008-00533-007 Heber E Ebert DD Lehr D Cuijpers P Berking M Nobis S Riper H The Benefit of Web- and Computer-Based Interventions for Stress: A Systematic Review and Meta-Analysis J Med Internet Res 2017 02 17 19 2 e32 10.2196/jmir.5774 28213341 v19i2e32 PMC5336602 Phillips EA Gordeev VS Schreyögg Jonas Effectiveness of occupational e-mental health interventions: a systematic review and meta-analysis of randomized controlled trials Scand J Work Environ Health 2019 11 01 45 6 560 576 10.5271/sjweh.3839 31184758 3839 Griffiths F Lindenmeyer A Powell J Lowe P Thorogood M Why are health care interventions delivered over the internet? A systematic review of the published literature J Med Internet Res 2006 06 23 8 2 e10 10.2196/jmir.8.2.e10 16867965 v8i2e10 PMC1550698 Rogers MA Lemmen K Kramer R Mann J Chopra V Internet-Delivered Health Interventions That Work: Systematic Review of Meta-Analyses and Evaluation of Website Availability J Med Internet Res 2017 03 24 19 3 e90 10.2196/jmir.7111 28341617 v19i3e90 PMC5384996 Heber E Lehr D Ebert DD Berking M Riper H Web-Based and Mobile Stress Management Intervention for Employees: A Randomized Controlled Trial J Med Internet Res 2016 01 27 18 1 e21 10.2196/jmir.5112 26818683 v18i1e21 PMC4749847 Drozd F Vaskinn L Bergsund HB Haga SM Slinning K Bjørkli Cato Alexander The Implementation of Internet Interventions for Depression: A Scoping Review J Med Internet Res 2016 09 08 18 9 e236 10.2196/jmir.5670 27608548 v18i9e236 PMC5034149 Behrendt D Ebert DD Spiegelhalder K Lehr D Efficacy of a Self-Help Web-Based Recovery Training in Improving Sleep in Workers: Randomized Controlled Trial in the General Working Population J Med Internet Res 2020 01 07 22 1 e13346 10.2196/13346 31909725 v22i1e13346 PMC6996739 Geraedts AS Kleiboer AM Wiezer NM van Mechelen W Cuijpers P Short-term effects of a web-based guided self-help intervention for employees with depressive symptoms: randomized controlled trial J Med Internet Res 2014 05 06 16 5 e121 10.2196/jmir.3185 24800966 v16i5e121 PMC4026573 Geraedts AS Kleiboer AM Twisk J Wiezer NM van Mechelen Willem Cuijpers P Long-term results of a web-based guided self-help intervention for employees with depressive symptoms: randomized controlled trial J Med Internet Res 2014 07 09 16 7 e168 10.2196/jmir.3539 25008127 v16i7e168 PMC4115257 Lazarus R Folkman S Stress, Appraisal, and Coping 1984 New York, NY Springer Tims MB Bakker A Derks D Daily job crafting and the self-efficacy – performance relationship Journal of Managerial Psychology 2014 29 5 490 507 10.1108/JMP-05-2012-0148 Bandura A Self-efficacy: Toward a unifying theory of behavioral change Advances in Behaviour Research and Therapy 1978 1 1 4 139 161 10.1016/0146-6402(78)90002-4 Jex SM Bliese PD Buzzell S Primeau J The impact of self-efficacy on stressor-strain relations: coping style as an explanatory mechanism J Appl Psychol 2001 06 86 3 401 9 10.1037/0021-9010.86.3.401 11419800 Ebert DD Lehr D Boß Leif Riper H Cuijpers P Andersson G Thiart H Heber E Berking M Efficacy of an internet-based problem-solving training for teachers: results of a randomized controlled trial Scand J Work Environ Health 2014 11 13 40 6 582 96 10.5271/sjweh.3449 25121986 3449 Rigotti T Schyns B Mohr G A Short Version of the Occupational Self-Efficacy Scale: Structural and Construct Validity Across Five Countries Journal of Career Assessment 2008 05 01 16 2 238 255 10.1177/1069072707305763 Guarnaccia C Scrima F Civilleri A Salerno L The Role of Occupational Self-Efficacy in Mediating the Effect of Job Insecurity on Work Engagement, Satisfaction and General Health Curr Psychol 2016 11 12 37 3 488 497 10.1007/s12144-016-9525-0 Ebert DD Franke M Zarski A Berking M Riper H Cuijpers P Funk B Lehr D Effectiveness and Moderators of an Internet-Based Mobile-Supported Stress Management Intervention as a Universal Prevention Approach: Randomized Controlled Trial J Med Internet Res 2021 12 22 23 12 e22107 10.2196/22107 34941541 v23i12e22107 PMC8734929 Ebert DD Lehr D Heber E Riper H Cuijpers P Berking M Internet- and mobile-based stress management for employees with adherence-focused guidance: efficacy and mechanism of change Scand J Work Environ Health 2016 09 01 42 5 382 94 10.5271/sjweh.3573 27249161 3573 Siegrist J Perrewe PL Ganster DC Effort-reward imbalance at work and health Historical and Current Perspectives on Stress and Health (Research in Occupational Stress and Well Being, Vol. 2) 2002 Bingley, UK Emerald Group Publishing Limited 261 291 Altman DG Better reporting of randomised controlled trials: the CONSORT statement BMJ 1996 09 07 313 7057 570 1 10.1136/bmj.313.7057.570 8806240 PMC2352018 Eysenbach G CONSORT-EHEALTH Group CONSORT-EHEALTH: improving and standardizing evaluation reports of Web-based and mobile health interventions J Med Internet Res 2011 12 31 13 4 e126 10.2196/jmir.1923 22209829 v13i4e126 PMC3278112 Michalsen A Jeitler M Brunnhuber S Lüdtke Rainer Büssing Arndt Musial F Dobos G Kessler C Iyengar yoga for distressed women: a 3-armed randomized controlled trial Evid Based Complement Alternat Med 2012 2012 408727 3 10.1155/2012/408727 23049608 PMC3463199 Cohen S Kamarck T Mermelstein R A Global Measure of Perceived Stress Journal of Health and Social Behavior 1983 12 24 4 385 10.2307/2136404 Siegrist J Wege N Pühlhofer Frank Wahrendorf M A short generic measure of work stress in the era of globalization: effort-reward imbalance Int Arch Occup Environ Health 2009 08 19 82 8 1005 13 10.1007/s00420-008-0384-3 19018554 Lehr D Koch S Hillert A Where is (im)balance? Necessity and construction of evaluated cut-off points for effort-reward imbalance and overcommitment Journal of Occupational and Organizational Psychology 2010 3 83 1 251 261 10.1348/096317909X406772 Beck AT Steer RA Brown GK Beck Depression Inventory Manual. 2nd ed 1996 San Antonio, TX Psychological Corporation Ebert DD Heber E Berking M Riper H Cuijpers P Funk B Lehr D Self-guided internet-based and mobile-based stress management for employees: results of a randomised controlled trial Occup Environ Med 2016 05 16 73 5 315 23 10.1136/oemed-2015-103269 26884049 oemed-2015-103269 Nixon P Boß Leif Heber E Ebert DD Lehr D A three-armed randomised controlled trial investigating the comparative impact of guidance on the efficacy of a web-based stress management intervention and health impairing and promoting mechanisms of prevention BMC Public Health 2021 08 05 21 1 1511 10.1186/s12889-021-11504-2 34353294 10.1186/s12889-021-11504-2 PMC8339390 Schaufeli W Leiter MP Maslach C Jackson SE Maslach C Jackson SE Leiter MP Maslach Burnout Inventory - General Survey (MI-GS) Maslach Burnout Inventory Manual 1996 1 Maslach Burnout Inventory Manual Palo Alto, CA Consulting Psychologists Press e1 Schaufeli W Salanova M González-Romá V Bakker A The Measurement of Engagement and Burnout: A Two Sample Confirmatory Factor Analytic Approach Journal of Happiness Studies 2002 2 3 1 71 92 10.1023/A:1015630930326 Ahlstrom L Grimby-Ekman A Hagberg M Dellve L The work ability index and single-item question: associations with sick leave, symptoms, and health--a prospective study of women on long-term sick leave Scand J Work Environ Health 2010 09 07 36 5 404 12 10.5271/sjweh.2917 20372766 2917 Lerner D Amick BC Rogers WH Malspeis S Bungay K Cynn D The Work Limitations Questionnaire Med Care 2001 01 39 1 72 85 10.1097/00005650-200101000-00009 11176545 Hautzinger M Allgemeine Depressions Skala (Manual) Psycontent 1993 2022-09-21 Göttingen, Germany Beltz Test GmbH http://www.psycontent.com/content/3x081j2m2732r345/ Radloff LS The CES-D Scale Applied Psychological Measurement 2016 07 26 1 3 385 401 10.1177/014662167700100306 Campbell-Sills L Stein MB Psychometric analysis and refinement of the Connor-davidson Resilience Scale (CD-RISC): Validation of a 10-item measure of resilience J Trauma Stress 2007 12 20 6 1019 28 10.1002/jts.20271 18157881 Richardson J Iezzi A Khan MA Maxwell A Validity and reliability of the Assessment of Quality of Life (AQoL)-8D multi-attribute utility instrument Patient 2014 11 23 7 1 85 96 10.1007/s40271-013-0036-x 24271592 PMC3929769 Boß Leif Lehr D Reis D Vis C Riper H Berking M Ebert DD Reliability and Validity of Assessing User Satisfaction With Web-Based Health Interventions J Med Internet Res 2016 08 31 18 8 e234 10.2196/jmir.5952 27582341 v18i8e234 PMC5023944 IBM Corp. SPSS Statistics for Windows IBM Corp 2017 2022-09-21 Armonk, NY IBM Corp https://www.ibm.com/in-en/products/spss-statistics Egbewale BE Lewis M Sim J Bias, precision and statistical power of analysis of covariance in the analysis of randomized trials with baseline imbalance: a simulation study BMC Med Res Methodol 2014 04 09 14 49 10.1186/1471-2288-14-49 24712304 1471-2288-14-49 PMC3986434 O'Connell NS Dai L Jiang Y Speiser JL Ward R Wei W Carroll R Gebregziabher M Methods for Analysis of Pre-Post Data in Clinical Research: A Comparison of Five Common Methods J Biom Biostat 2017 02 24 8 1 1 8 10.4172/2155-6180.1000334 30555734 PMC6290914 Schafer JL Graham JW Missing data: Our view of the state of the art Psychological Methods 2002 7 2 147 177 10.1037/1082-989x.7.2.147 Jacobson NS Truax P Clinical significance: A statistical approach to defining meaningful change in psychotherapy research Journal of Consulting and Clinical Psychology 1991 59 1 12 19 10.1037/0022-006X.59.1.12 Janicki-Deverts D Cohen S Who's Stressed? Distributions of Psychological Stress in the United States in Probability Samples from 1983, 2006, and 2009 Journal of Applied Social Psychology 2012 6 42 6 1320 1334 10.1111/j.1559-1816.2012.00900.x Altman DG Andersen PK Calculating the number needed to treat for trials where the outcome is time to an event BMJ 1999 12 04 319 7223 1492 5 10.1136/bmj.319.7223.1492 10582940 PMC1117211 Hayes A Introduction to Mediation, Moderation and Conditional Process Analysis. A Regression-Based Approach (2nd Edition) 2018 New York, NY The Guilford Press Stratton E Jones N Peters S Torous J Glozier N Digital mHealth Interventions for Employees: Systematic Review and Meta-Analysis of Their Effects on Workplace Outcomes J Occup Environ Med 2021 08 01 63 8 e512 e525 10.1097/JOM.0000000000002267 34050095 00043764-900000000-97861 Unterbrink T Pfeifer R Krippeit L Zimmermann L Rose U Joos A Hartmann A Wirsching M Bauer J Burnout and effort-reward imbalance improvement for teachers by a manual-based group program Int Arch Occup Environ Health 2012 08 85 6 667 74 10.1007/s00420-011-0712-x 22038086 Schyns B von Collani G A new occupational self-efficacy scale and its relation to personality constructs and organizational variables European Journal of Work and Organizational Psychology 2002 06 11 2 219 241 10.1080/13594320244000148 Engels M Boß Leif Engels J Kuhlmann R Kuske J Lepper S Lesener L Pavlista V Diebig M Lunau T Ruhle SA Zapkau FB Angerer P Hoewner J Lehr D Schwens C Süß Stefan Wulf IC Dragano N Facilitating stress prevention in micro and small-sized enterprises: protocol for a mixed method study to evaluate the effectiveness and implementation process of targeted web-based interventions BMC Public Health 2022 03 26 22 1 591 10.1186/s12889-022-12921-7 35346127 10.1186/s12889-022-12921-7 PMC8959270 Zarski A Lehr D Berking M Riper H Cuijpers P Ebert DD Adherence to Internet-Based Mobile-Supported Stress Management: A Pooled Analysis of Individual Participant Data From Three Randomized Controlled Trials J Med Internet Res 2016 06 29 18 6 e146 10.2196/jmir.4493 27357528 v18i6e146 PMC4945816 Baumeister H Reichler L Munzinger M Lin J The impact of guidance on Internet-based mental health interventions — A systematic review Internet Interventions 2014 10 1 4 205 215 10.1016/j.invent.2014.08.003 Clausen T Madsen IE Christensen KB Bjorner JB Poulsen OM Maltesen T Borg V Rugulies R The Danish Psychosocial Work Environment Questionnaire (DPQ): Development, content, reliability and validity Scand J Work Environ Health 2019 07 01 45 4 356 369 10.5271/sjweh.3793 30592500 3793