The study was reported according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline extension for reporting scoping reviews [16]; the review protocol was not registered with a database. Citations were retrieved from MEDLINE, Cochrane database, Embase, Emcare, Scopus, CINAHL, and Web of Science, using search terms grouped by key concepts (VC and evaluation or quality measurement; Multimedia Appendix 1); syntax was translated as appropriate for included databases. Review articles published from January 2015 to May 2023 were retained; earlier articles were excluded for multiple reasons: (1) technological changes, (2) the need to balance comprehensiveness of the search with manageability of the volume of articles, and (3) the inclusion of reviews that incorporated studies published before 2015, which allowed us to capture relevant earlier work.

Titles and abstracts were independently screened for relevance by 2 members of the research team trained in literature review methods (MP and AA, JS, or SH), whereas full-text articles were independently screened for inclusion by 2 members of the research team (MP and AA or JS). Screening was undertaken in Covidence (Veritas Health Innovation, Melbourne, Australia). Articles were retained if they reported on any type of systematic review with the exclusion of narrative reviews and reviews of reviews, were published since January 2015, examined VC delivered in the outpatient setting, were published in English, and reported on some evaluation measure. For the purposes of this work, VC was defined as any synchronous communication between patients and clinicians (people providing direct patient care) that takes place remotely.

Eligibility issues were addressed through consensus discussions with a third reviewer (MKK) as required. Articles that reported on virtual reality interventions or reported on eHealth or mobile health interventions that were not delivered synchronously or were undefined were excluded. Measures were defined as any quantitative or qualitative evaluation of the performance or impact of VC on processes, outcomes, or systems. Articles were excluded if they were not a literature review (eg, primary results, commentaries, letters, and protocols). As there are different legal and ethical requirements for the use of VC in pediatric populations, and the role of the caregiver in care is different from that of adult populations, articles that dealt exclusively with pediatric populations were excluded. Conference abstracts in the absence of an accompanying full-text article were excluded as they provided insufficient details for analysis.

Details of retained articles (dates of publication, clinical condition or population, description of the modality of VC delivery, details of measures, data collection methods, barriers to VC, and key findings) were abstracted by 1 member of the study team (AA) into a standardized abstraction template in Covidence. To ensure abstraction reliability, a second reviewer (MP) extracted data from a subset of 15 randomly selected manuscripts; no discrepancies were found between reviewers.

The abstracted data were exported as a CSV file to Microsoft Excel for analysis. Measures were grouped using deductive thematic analysis against the 3 domains and their constructs of the Proctor outcomes framework for implementation research (Table 1) [14]. Measures were captured under the construct specified within the original review article. As such, similar measures may be listed under more than one construct of the Proctor framework. The proportion of retained articles reporting on a measure was calculated out of those review articles reporting on the corresponding domain or construct, as appropriate.

The search returned 44,048 articles, of which 1233 were retained for analysis. A PRISMA diagram is included in Figure 1, and details of the retained articles are described in Multimedia Appendix 2. A substantial proportion of the review articles (885/1233, 71.8%) were published following the shift to the adoption of virtual visits as a result of the COVID-19 pandemic (Table 2). Articles were frequently not specific to a clinical context or condition (197/1233, 16.0%), or dealt specifically with mental health conditions (181/1233, 14.7%) or cardiovascular conditions ( 121/1233, 9.8%). Most review articles evaluated telephone and video visits collectively (691/1233, 56.0%), or focused solely on telephone-based visits (256/1233, 20.8%). Client outcomes were the most commonly evaluated domain (900/1233, 73.0%), followed by service outcomes ( 507/1233, 41.1%) and implementation outcomes (476/1233, 38.6%).

For each of the domains and constructs, Multimedia Appendix 3 provides details on the evaluation measures used to date, whereas Table 3 summarizes the high-level key findings. Across each of the domains, we found that articles frequently chose measures that did not match the construct that they indicated they were evaluating. For example, measures of acceptability were used interchangeably to evaluate acceptability, satisfaction, and usability of VC, despite these constructs being conceptually different. Additionally, we observed high heterogeneity in the measures that have been used to evaluate VC, particularly for acceptability, adoption, feasibility, and fidelity, which suggests a lack of consensus about what should be measured and how.

Of those review articles reporting on implementation outcomes (n=476), the most commonly reported implementation measures were related to costs of VC (221/476, 46.4%), adoption into practice (135/476, 28.4%), and acceptability (109/476, 22.9%; Multimedia Appendix 3). However, there appeared to be a lack of consensus on definitions of outcomes within the implementation domain, particularly for acceptability, adoption, and feasibility, where many review articles reported on proxy rather than direct measures or used the concepts interchangeably. Of articles reporting on adoption or acceptability, evaluations of the patient perspective were far more common than those of clinicians or the health system (adoption: patient 92.6% vs clinician 5.2% vs system 1.5%; acceptability: patient 96.3% vs clinician 17.4%).

Few review articles reported on caregiver or trainee perspectives on implementation despite reports that these groups may have unique experiences with VC beyond those of patients and clinicians. There were few articles examining penetration of VC (24/476, 5.0%), and those that did most frequently described availability of virtual visits (5/24, 20.8%), satisfaction of key stakeholders with access to VC (4/24, 16.6%), or sociodemographic factors associated with access to VC (4/24, 16.6%), most often race or ethnicity (3/24, 12.5%). Measures of appropriateness of virtual visits for different clinical scenarios, patient populations, or visit types were sparsely reported (9/476, 1.9%), as were measures of long-term adoption or sustainability (10/476, 2.1%). Additionally, few articles examined fidelity of virtual visits (45/476, 9.5%), and those that did focused mostly on fidelity of the intervention (43/45, 95.6%), examining diagnostic accuracy (32/43, 74.4%) or concordance with an intervention protocol (10/43, 23.2%).

Of those review articles reporting on service outcomes (n=507), the most commonly reported outcome was effectiveness (365/507, 72.0%); while there was a high heterogeneity of measures, effectiveness was most commonly reported as uptake of health behaviors as a result of exposure to VC (201/365, 55.1%), adherence to treatment (123/365, 30.1%), or as a change in self-efficacy on a validated scale (111/365, 30.4%; Multimedia Appendix 3). Few review articles evaluated the safety of VC (25/507, 4.9%), and those that did only covered a narrow range of topics, including adverse event rates (9/25, 36.0%) and acute care utilization (6/25, 24.0%), generally from the clinician perspective. Additionally, few review articles evaluated the impact of VC on health equity (28/507, 5.5%), with most (25/28, 89.3%) focusing on marginalized or vulnerable populations, especially Indigenous populations (8/25, 32.0%) and racialized populations (7/25, 28.0%). There was limited evaluation of equity issues around VC as they related to gender (4/28, 14.3%) or language/literacy barriers (1/28, 3.6%). Of note, none of the articles described the use of objective or validated measures for assessing disparities in care. Of articles examining the quality of clinical interactions delivered virtually (36/507, 7.1%), most focused on capturing the patient perspective (34/36, 94.4%), whereas few captured the clinician perspective (4/36, 11.1%), and usage of existing validated measures was limited.

The majority of the retained review articles included client outcomes (n=900). Approximately half of the review articles reporting on client outcomes evaluated satisfaction with virtual visits (403/900, 44.7%), although proxy measures such as acceptability, perceived usefulness, and adoption were prevalent and heterogeneity of validated measures was high (Table 3 and Multimedia Appendix 3). Both satisfaction and experience with VC were more often evaluated from the perspective of patients rather than clinicians (satisfaction: 93.3% vs 28.5%; experience: 59.6% vs 31.8%). Additionally, caregiver satisfaction was rarely evaluated, whereas few reviews examined caregivers’ experiences with VC (40/151, 26.4%). Usability was more frequently evaluated from the patient rather than clinician perspective (89.7% vs 12.1%), and patient-focused measures of usability were more comprehensive, as they captured aspects of functionality, such as ease of use, perceptions of technical features, and factors associated with patterns of usage that were not included in clinician-focused evaluations.

A minority of articles evaluated privacy and security of VC platforms (7/62, 11.3%), most often through qualitative themes from inquiry around patient and clinician perceptions (5/7, 71.4%), although none cited objective measures. The most commonly reported client outcomes were clinical outcomes (734/900, 81.5%), including both psychosocial (438/734, 59.7%) and physical (560/734, 76.3%). While there was high heterogeneity of measures that were used, they were generally appropriate to the clinical context or population under study and included widely used objective physical measurements and validated survey instruments.

There has been substantial growth in the literature evaluating outcomes of VC, especially since the start of the COVID-19 pandemic. The majority of review articles evaluating VC focused on client outcomes (900/1233, 73.0%), which included usability or functionality of the VC systems (62/900, 6.88%); satisfaction and experience with VC from the patient, caregiver, or clinician perspectives (403/900, 44.7%), and clinical outcomes of care delivered virtually (734/900, 81.5%), including mortality. Our study highlights gaps in current evaluations of VC. Through this work, we have identified a number of opportunities to improve how VC is evaluated, what aspects of VC have been understudied, and what type of methodological work needs to be undertaken to facilitate future assessments. To our knowledge, this is the largest scoping literature review to date examining the evaluation of VC across all clinical contexts.

Despite the growing body of published work stressing the importance of evaluating implementation in understanding interventions, given the influence of context and implementation processes on the success of an intervention [17-19], fewer articles reported outcomes related to implementation of VC ( 476/1233, 38.6%). Of the articles examining implementation, most of these articles focused on capturing costs of implementing, delivering, or receiving virtual visits (221/476, 46.4%), whereas relatively few examined intervention or implementation fidelity (45/476, 9.5%); penetration or access to virtual visits (24/476, 5.0%); or appropriateness of VC for different types of visits, patient populations, or clinical contexts (9/476, 1.9%). In Table 4, we highlight recommendations for the conduct of future VC evaluations, areas where research should fill in current evidence gaps, and areas for future theoretical and conceptual development.

The quality of evaluation of concepts within the implementation domain was particularly poor, as there appeared to be a lack of consensus on how to measure acceptability, adoption, feasibility, and fidelity, and poor adherence to conventional definitions of these concepts. This may stem from the lack of VC-specific validated measures, as many of the existing measures, including the Telemedicine Satisfaction and Acceptance Scale, Unified Theory of Acceptance, and Use of Technology Scale, combine different conceptual elements of usability and satisfaction with acceptance [20]. Existing organizations with an interest in quality measurement, such as the Agency for Healthcare Research and Quality, likely have a role to play in standardizing these definitions moving forward. Additionally, the development of a centralized repository of VC measures could be beneficial in improving reproducibility and comparability of findings of future VC evaluations.

There are several existing, validated measures of patient-centeredness of care [21], including the Picker [22] and the English Person-Centered Climate Questionnaire-Patient version [23]; however, these measures appear to be underutilized, as none of the included articles reported on using objective, validated measures. Moving forward, research should leverage the existing validated tools when evaluating the impact of virtual visits on patient-centeredness of care.

Few review articles evaluated the impact of VC on health equity (28/507, 5.5%), with most (25/28, 89.3%) focusing on marginalized or vulnerable populations, especially Indigenous populations (8/25, 32.0%) and racialized populations (7/25, 28.0%). Despite growing concerns of the potential impacts of VC on health equity and broadening disparities in access to care [24-26], there was limited evaluation of specific inequities, such as sociodemographic status, language and accessibility, and intersecting identities. Additionally, articles that did examine disparities in care did not always adhere to standardized definitions of concepts, such as reporting on gender versus sex. Cultural appropriateness of VC, particularly around who is involved in or able to observe interactions, and patient preferences surrounding involvement of family and friends in treatment decision-making was highlighted by patients, clinicians, and stakeholders as a major barrier to VC; however, this concept did not appear to be formally evaluated within the current body of literature. Future evaluations should include examinations of cultural competency and cultural appropriateness of virtual visits and make use of existing measures and tools, such as the Consumer Assessment of Healthcare Providers and Systems cultural competence patient-facing questionnaire [27], the Multicultural Counseling Self Efficacy Scale—Racial Diversity Form [27], clinician-facing questionnaire [28], and the Cultural Safety in Health Systems framework to guide system-level evaluation [29]. Additionally, future work should focus on generating robust evidence through multimethod evaluations [30], which triangulate qualitative data on patient perspectives around disparities in their care [25] with objective evaluations of patterns of VC delivery [31,32].

Studies evaluating clinical outcomes used accepted objective clinical biomarkers, vitals, and laboratory values for measures of clinical effectiveness wherever possible and adhered to accepted definitions of measures of mortality. However, appropriate comparator groups were not always used, and care was often hybrid rather than strictly in-person versus virtual, which presented additional challenges in evaluation. Future work should consider appropriate controls and comparators when evaluating clinical effectiveness, such as historical controls or contemporaneous, nonexposed comparators where appropriate.

VC often leverages caregivers as a care partner, providing technical support and enabling virtual interactions [33,34]; however, there was limited evaluation of the caregiver experience, satisfaction with and acceptance of VC as a unique stakeholder in VC delivery, beyond measures of caregiver burden, and impact on mental health. Additionally, clinician experience and acceptance of VC have implications for availability, adoption, and long-term sustainability of VC; however, relative to patients, few articles examined the clinician perspective. Future evaluation and research should include measures of the caregiver and clinician experiences with VC as a unique and pivotal perspective.

Our findings must be interpreted within the limitations of our methods. Given the substantial body of literature surrounding VC and the volume of literature reviews published on the topic, we chose to undertake a review of reviews [35]. This methodology afforded us the opportunity to systematically search across clinical conditions, as there have been many pockets of VC innovation globally, including delivery of specialist care for cardiology and dermatology, ongoing treatment of mental health conditions, and delivery of care to rural and remote communities, while still returning a feasible number of citations to abstract under reasonable timelines. However, this impacted the granularity of the abstraction, as it is dependent on the authors of reviews to abstract the primary articles accurately and may have led to underreporting of some VC measures. Additionally, our definition of VC was restricted to synchronous, outpatient interactions between clinicians and patients. While asynchronous forms of VC, such as secure messaging and text messaging, are gaining traction [36], we felt that this may have introduced too much heterogeneity in the aim of this study, and we did not feel there was sufficient evidence base to include them in a review of reviews at this time. Finally, we restricted our search to only full-text articles published in English for practical reasons. As most countries globally adopted VC in some capacity as part of their pandemic response [37], they may have missed some relevant citations, which were published in other languages.

A better understanding of the short- and long-term impacts of virtual visits is needed to inform optimization of models of VC delivery, reimbursement structures, critical infrastructure investments, and health policy. Work is needed to standardize measure definitions as they relate to VC for key concepts particularly in the implementation domain. Standardization is pivotal for improving reproducibility, comparability, and generalizability of findings across different clinical settings, VC delivery modalities, and health systems, to drive future VC policy, clinical adoption, and patient engagement. Development of a centralized repository of VC measures could be beneficial in improving reproducibility and comparability of findings of future VC evaluations. Future studies should also include the caregiver and the clinician as unique perspectives in evaluations and should embed systematic evaluations of the impact of social determinants of health on VC access, adoption, and impressions of care using both qualitative and quantitative methodologies to get a more fulsome understanding of disparities.