Published on 29.08.03 in Vol 5, No 3 (2003)
The Impact of Health Information on the Internet on Health Care and the Physician-Patient Relationship: National U.S. Survey among 1.050 U.S. Physicians
Background: Public use of the Internet for health information is increasing but its effect on health care is unclear. We studied physicians' experience of patients looking for health information on the Internet and their perceptions of the impact of this information on the physician-patient relationship, health care, and workload.
Methods: Cross-sectional survey of a nationally-representative sample of United States physicians (1050 respondents; response rate 53%).
Results: Eighty-five percent of respondents had experienced a patient bringing Internet information to a visit. The quality of information was important: accurate, relevant information benefited, while inaccurate or irrelevant information harmed health care, health outcomes, and the physician-patient relationship. However, the physician's feeling that the patient was challenging his or her authority was the most consistent predictor of a perceived deterioration in the physician-patient relationship (OR = 14.9; 95% CI, 5.5-40.5), in the quality of health care (OR = 3.4; 95% CI, 1.1-10.9), or health outcomes (OR = 5.6; 95% CI, 1.7-18.7). Thirty-eight percent of physicians believed that the patient bringing in information made the visit less time efficient, particularly if the patient wanted something inappropriate (OR = 2.5; 95% CI, 1.5-4.4), or the physician felt challenged (OR = 3.6; 95% CI, 1.8-7.2).
Conclusions: The quality of information on the Internet is paramount: accurate relevant information is beneficial, while inaccurate information is harmful. Physicians appear to acquiesce to clinically-inappropriate requests generated by information from the Internet, either for fear of damaging the physician-patient relationship or because of the negative effect on time efficiency of not doing so. A minority of physicians feels challenged by patients bringing health information to the visit; reasons for this require further research.
J Med Internet Res 2003;5(3):e17)
An increasing proportion of the public is using the Internet for health information . This is expected to have a "profound effect on medicine" [ ], but it is unclear whether this effect will be beneficial or harmful. The advantages of the Internet as a source of health information include convenient access to a massive volume of information, ease of updating information, and the potential for interactive formats that promote understanding and retention of information. Health information on the Internet may make patients better informed, leading to better health outcomes, more appropriate use of health service resources, and a stronger physician-patient relationship [ ]. However, health information on the Internet may be misleading or misinterpreted, compromising health behaviors and health outcomes, or resulting in inappropriate requests for clinical interventions [ ]. Physicians may accede to inappropriate requests, either because refusal is time consuming, or because they fear refusal would weaken the physician-patient relationship [ , ]. Responding to inappropriate patient requests may be particularly difficult in managed care, where patients may believe that physician refusals may be motivated by the need to control costs [ ]. Some physicians may have difficulty adjusting to a more-equal role with patients [ ] or may experience conflict with more-assertive patients [ ]. There is little information on physicians' experience with patients who have sought health information on the Internet.
We surveyed a nationally-representative sample of physicians about their experience with patients bringing health information from the Internet to office visits. Our aims were to determine physicians' perceptions of the effects of patients bringing health information from the Internet on the physician-patient relationship; time efficiency of the visit; quality of care received by the patient; and patient's health outcomes.
Two thousand physicians were randomly selected from the national list of physicians provided by the Medical Marketing Service, Inc (MMS). The Medical Marketing Service list is based on the national database of the American Medical Association (AMA) which includes both members and nonmembers of the American Medical Association, and is updated weekly. The American Medical Association database contains over 650000 physicians, and is the most-complete list of physicians available in the United States. Physicians who currently spent over 20 hours a week on direct patient care were included in the survey. The sample was stratified by specialty: primary care, medical specialty, or surgical specialty. Primary care included family practice, general practice, internal medicine, and pediatrics. Ob-Gyn was classified as a surgical specialty.
The questionnaire was developed following literature review and focus-group discussions. It was pretested to ensure that the instrument was easy to complete, all areas of interest were covered, and no questions were ambiguous. It consisted of closed-end questions, took approximately 12 minutes to complete, and was in 3 parts. The entire sample received Part 1 of the questionnaire, which elicited general information about views on health information on the Internet and direct-to-consumer advertising (DTCA). Questions included general views on accuracy and effects of such information, and personal use of the Internet at work. Part 2 was sent to a random 50% of the sample, and requested information about the last time a patient brought in information from the Internet. "Last-time" methodology was used to minimize recall bias. Areas explored were the relevance and accuracy of the information, physicians' perceptions of why the patient had brought the information, physicians' responses to the patient, and their views about the impact on health care, health outcomes, and the physician-patient relationship. The other 50% of the sample received a different Part 2, which explored these same areas but with regard to the last time a patient brought in information from direct-to-consumer advertising. The direct-to-consumer advertising data are presented elsewhere . Part 3 was received by the entire sample and obtained demographic and workload information: hours per week on face-to-face consultations, on other tasks related to patient care, and on administrative tasks; numbers of patients seen per week; practice income; proportions of patients on Medicaid, from minority groups, having household incomes of less than $20000 per annum, and without health insurance; geographic setting of practice; age and racial origin of respondent. This was supplemented with information from the Medical Marketing Service database including specialty, year of graduation from medical school, geographic region (East, South, Midwest, West), whether hospital-based or office-based, and whether trained in the United States or overseas.
Data collection was undertaken between November 2000 and February 2001. The questionnaire was mailed to the selected physicians with a check for US $35 as a token of appreciation for completing the questionnaire. Up to 3 reminders were sent and additional telephone contact made with nonresponders. Of the original 2000 physicians sent the survey, 38 were ineligible because they were deceased, retired, or no longer in practice; and 1050 physicians completed the questionnaire (response rate 53%). Of these, 515 received the Internet version of the questionnaire, and 535 the direct-to-consumer advertising version.
Data were weighted to represent the national population of physicians in the Medical Marketing Service database who spend 20 or more hours per week on direct patient care, using the Medical Marketing Service variables mentioned above. As can be seen in, there is little difference between weighted and unweighted data, confirming that respondents were representative of US (United States) physicians.
The analytic approach focused on evaluating univariate and multivariate relationships with 4 clinically-important outcomes — change in physician-patient relationship; time efficiency; quality of care; and patient health outcome — each of which was assessed on a 3-point scale (improved vs no difference vs worsened). All the demographic, workload, and practice variables listed inwere run against each of these 4 outcome variables. Univariate relationships were calculated using the chi-square statistic or Fisher exact test as appropriate. In addition, univariate relationships were also investigated for an intermediate outcome: whether or not the physician did what the patient requested (yes completely vs yes partially vs no), a variable which in turn is evaluated for its relationship with the 4 main outcome variables.
Although several of the workload and practice characteristics were assessed as continuous variables (eg, percentage of patients who were uninsured, average number of patients seen per week), most were highly skewed, so medians and interquartile ranges are reported for these data. These variables were split at the 75th percentile for analysis of univariate relationships to test for the influence of these factors. This split was chosen over a median split to maximize the opportunity for an effect to be visible.
Separately for each outcome variable, correlates with chi-square statistics achieving P< .20 were analyzed using a stepwise multiple-logistic regression procedure to determine the "most-important" correlates, where importance is defined solely by statistical criteria. Each analysis went through several iterations, with each new iteration employing successively more-stringent statistical criteria for inclusion in the model. Each iteration included consideration of a model yielded by a forward-stepwise procedure and a model yielded by a backward-stepwise procedure. Final models include all correlates with a significant ( P< .05) or near-significant (.05 < P<.10) likelihood ratio test while still achieving adequate fit, operationalized as P> .20 on the Hosmer-Lemeshow goodness-of-fit test.
As all data were weighted (except where specified), the appropriate procedures to correct P values and standard errors were undertaken. We used the SVYTAB procedure in STATA to obtain the Rao and Scott F-test P-values , and the SVYLOGIT procedure in STATA to obtain corrected standard errors for parameter estimates.
Demographic and Other Characteristics of the Sample
The characteristics of the respondents before and after weighting are presented in. Weighting made only minimal difference to the characteristics of the sample, confirming that respondents were representative of US physicians. From this point on, all data presented are weighted.
Personal Use of the Internet
Sixty-one percent (n = 639; 95% CI, 58%-64%) of all respondents used the Internet in their own practice. In this group, the most-frequent uses were to obtain scientific information such as articles or guidelines (88%; 95% CI, 86%-91%) or to e-mail colleagues (63%; 95% CI, 59%-67%). Obtaining clinical information about patients, such as lab results (28%; 95% CI, 25%-32%), and e-mailing patients (16%; 95% CI, 13%-18%) were much less common uses of the Internet by physicians.
Views About Health Information on the Internet.
Overall, respondents were positive about the recent increase in health information on the Internet, with 75% (95% CI, 72%-77%) of the total sample thinking that it was a good or very-good thing. Only 15% (95% CI, 13%-17%) believed that it was a bad thing, and the remainder were neutral. Similarly, most physicians (77%; 95% CI, 74%-79%) stated that they had encouraged patients to look for information, although only 35% (95% CI, 32%-38%) had referred patients to Web sites.
Views About Patient Responses to the Internet
Eighty-five percent (95% CI, 82%-87%) of all respondents had experienced an occasion when a patient brought information from the Internet to a visit. For most physicians this is still a relatively-rare event; 59% (95% CI, 56%-62%) of respondents stated that less than one fifth of their patients had done this. 87% (95% CI, 85%-89%) of physicians perceived their patients as being concerned about the quality of information on the Internet, and 84% (95% CI, 82%-86%) of respondents rated their patients as only fair or poor (rather than good, very good, or excellent) at appraising the quality of information on a Web site .
Results From Respondents Whose Patients Brought Health Information on the Internet to a Consultation
Last Consultation With a Patient Who Had Brought in Information on the Internet
A random subsample (n = 519) was asked about the last time a patient had brought in health information on the Internet to a consultation and 430 reported that a patient had done so. The remaining data are from these 430 respondents.
Quality of Information
Most respondents believed that the last time a patient had brought in health information from the Internet, the information had been very (18%; 95% CI, 15%-22%) or somewhat (64%; 95% CI, 59%-68%) relevant to that patient's problems and very (8%; 95% CI, 5%-11%) or somewhat (66%; 95% CI, 61%-71%) accurate.
Reasons for Bringing Information to the Visit and Response to Requests for Interventions
Respondents perceived that the majority of these patients (90%; 95% CI, 87%-93%) had brought them the information because they wanted the physician's opinion on it. Physicians reported that patients sometimes also wanted a change in medication (31%; 95% CI, 27%-36%), a test (26%; 95% CI, 22%-31%), or a referral to a specialist (13%; 95% CI, 10%-17%).
Physicians usually did what the patient wanted, either completely (23%; 95% CI, 19%-28%) or partially (59%; 95% CI, 54%-63%). Univariate associations are shown in.
On multivariate analysis, only 3 factors independently predicted not doing what the patient wanted. Thinking that the patient's request was not appropriate for their health was the most important factor (OR = 4.4; 95% CI, 2.4-8.0), followed by thinking the information that the patient brought in was not accurate (OR = 3.0; 95% CI, 1.6-5.5) and the type of specialty the physician was in. Medical specialists were more likely than primary care physicians and surgical specialists not to do what the patient wanted (for medical specialist compared to primary care physician OR = 2.8; 95% CI, 1.4-5.5, and for medical specialist compared to surgical specialist OR = 2.0; 95% CI, 1.02-4.1).
Effect on Physician-Patient Relationship
Most physicians believed that the patient bringing information to the visit had had a beneficial (38%; 95% CI, 33%-43%) or neutral (54%; 95% CI, 49%-59%) effect on the physician-patient relationship. Univariate associations are shown in.
Multivariate analysis yielded 4 factors that were independently associated with a worsening of the physician-patient relationship. The physician feeling that the patient was challenging their authority was the strongest predictor (OR = 14.9; 95% CI, 5.5-40.5) followed by the physician believing that the patient's request was not appropriate for their health (OR = 9.9; 95% CI, 2.7-36.4). Not feeling that the patient was taking responsibility for their health was independently associated with a worsening of the physician-patient relationship (OR = 4.6; 95% CI, 1.7-12.5), as was not doing what the patient wanted (OR = 4.0; 95% CI, 1.7-9.7).
Effect on Time Efficiency
Thirty-eight percent (95% CI, 34%-43%) of physicians believed that the effect of the patient bringing information to the consultation harmed their time efficiency while only 16% (95% CI, 13%-20%) believed that it had helped it. Univariate associations are shown in.
Multivariate analysis showed that many of these factors were independently associated. Physicians trained in the United States were more likely than physicians trained overseas to feel that time efficiency was worsened (OR = 5.8; 95% CI, 2.0-17.0). Other independently-associated workload factors were not having enough time to discuss the information (OR = 2.6; 95% CI, 1.6-4.3) and seeing over 100 patients per week (OR = 1.8; 95% CI, 1.1-3.0). The physician thinking that the request was not appropriate for the patients health (OR = 2.5; 95% CI, 1.5-4.4), feeling that the patient was challenging their authority (OR = 3.6; 95% CI, 1.8-7.2), or not thinking that the patient was taking responsibility for their health (OR = 2.2; 95% CI, 1.3-3.8) were also independently associated with worsened time efficiency.
Effect on Quality of Care
Most physicians believed that the information made no difference to the quality of care the patient received (70%; 95% CI, 66%-74%). More physicians believed that it had been beneficial (25%; 95% CI, 21%-29%) than deleterious (5%; 95% CI, 3%-8%) (). Logistic regression revealed that the only factor independently associated with a worsening of quality of care was the physician perceiving that the patient was challenging their authority (OR = 3.4; 95% CI, 1.1-10.9).
Effect on Health Outcomes
Seventy-five percent (95% CI, 71%-79%) of physicians believed that the information had made no difference to the patient's health outcome, 21% (95% CI, 17%-25%) believed that it had improved the health outcome, and only 4% (95% CI, 2%-6%) believed that it had been deleterious (). On multivariate analysis, only 2 factors were independently associated with the physician's perception of a worsened health outcome: information that was inaccurate (OR = 5.7; 95% CI, 1.6-20.5), or the physician feeling that the patient was challenging their authority (OR = 5.6; 95% CI, 1.7-18.7). Workload and practice characteristics were not associated with effect on health outcomes.
This is the first large nationally-representative sample of physicians to study physician perceptions of the impact of health information on the Internet on quality of health care, health outcomes, health service utilization, and the physician-patient relationship that we could find by searching MEDLINE. We found evidence of both good and bad effects. Our findings have implications for practicing clinicians, policy makers, and researchers.
The Quality of Online Information is Paramount
Physicians believed that patients bringing in accurate, relevant online information is beneficial and welcomed it. Conversely, physicians believed that inaccurate or irrelevant information harms the quality of care, health outcomes, time efficiency, and the physician-patient relationship. Thus improving the accuracy and relevance of online information available to patients may improve outcomes of interest to health care providers, payers, and consumers. The policy challenge is how to improve the quality of online health information, given the large number of health-related Web sites and the ease with which sites can be updated. Suggestions include "kitemarks" (seals of approval) for quality Web sites, codes of conduct for development and content of Web sites, market forces, directing users to trusted Web sites, filters, rating instruments for users, and public education in evaluating the quality of online information [- ]. The effectiveness and practicality of these suggestions remain unproven [ - ].
Responding to Patient Requests for Clinically Inappropriate Interventions
US physicians may feel in a quandary when patients request an inappropriate clinical intervention that they learned about online. Ethically, physicians should refuse inappropriate requests in order to avoid harming the patient and to use health service resources prudently. However, previous studies have suggested that refusing patient requests will reduce patient satisfaction [, ]. Physicians may be reluctant to jeopardize patient satisfaction because it is used as an index of quality, and can impact on physician income. This dilemma may be particularly acute in managed care, where patients believe that physicians refuse requests on financial grounds rather than clinical grounds [ ]. Physicians also perceive that refusing clinically-inappropriate requests is damaging to time efficiency. This perception, or reality, may make physicians unwilling to engage in such discussions, and may, in turn, lead to more inappropriate requests being filled, with subsequent upward pressure on health care costs.
Physicians Who Feel Challenged
Seventeen percent of physicians felt that patients were challenging their authority during the visit. This reaction was strongly associated with harms to the physician-patient relationship, quality of care, health outcomes, and time efficiency. Our study cannot determine why physicians feel challenged. Some physicians may be having difficulty adjusting to a more-equal relationship, where the patient has greater access to medical information . Alternatively, some patients may fail to acknowledge the physician's clinical expertise. This is an area for further research.
Although our response rate is only moderate at 53%, it compares well to other surveys of Internet use by physicians. Because our sample was representative of all US physicians in terms of age, gender, specialty, location of practice, and practice income our results are likely to generalize to all US physicians. In contrast, previous surveys have examined specific branches of medicine , used convenience samples [ ] or Internet-literate samples [ ], had unacceptably-low (21%) response rates [ ], or had very-small samples [ ]. Response rates in other recent surveys of US physicians are lower than ours [ - ], and the absence of substantive differences between responders and nonresponders argues against the presence of systematic selection bias.
As with all cross-sectional studies, we cannot determine causality, nor do we have objective data on whether patient requests were truly inappropriate or on quality of care or health outcomes. However, our measures are plausible because physicians address the appropriateness of care and outcomes daily on a professional basis. Patient perceptions of these consultations may have been different, but our results from a population survey of public perceptions of the effects of health information on the Internet are not dissimilar .
Health care organizations, payers, and providers have a strong interest in ensuring both that health information on the Internet is accurate and that physicians have the necessary skills to respond to patients who bring in such information. Vigorous leadership in these areas will be needed if the effect of the Internet on medicine is to be truly beneficial.
We are grateful to the Robert Wood Johnson Foundation for funding the study and to the Commonwealth Fund for awarding a Harkness Fellowship in Health Care Policy 2001-2002 to Elizabeth Murray, enabling her to work on this study.
Conflicts of Interest
Karen Donelan was Medical Vice-Director of a company providing health information and advice through the Internet. She took up this post after completing the protocol for the study and design of the survey instruments, and had no further input into the fieldwork or analysis of the data.
- Lenhart A, Horrigan J, Rainie L, Allen K, Boyce A, Madden M, et al. The ever-shifting Internet population. a new look at Internet access and the digital divide. Washington, DC: Pew Internet & American Life Project. 2003 Apr 16. URL: http://www.pewinternet.org/reports/pdfs/PIP_Shifting_Net_Pop_Report.pdf [WebCite Cache]
- Kassirer JP. Patients, physicians, and the Internet. Health Aff (Millwood) 2000;19(6):115-123 [FREE Full text] [Medline] [CrossRef]
- Eysenbach G, Köhler C. Does the internet harm health? Database of adverse events related to the internet has been set up. BMJ 2002 Jan 26;324(7331):239. [Medline] [CrossRef]
- Gallagher TH, Lo B, Chesney M, Christensen K. How do physicians respond to patient's requests for costly, unindicated services? J Gen Intern Med 1997 Nov;12(11):663-668. [Medline] [CrossRef]
- Bell RA, Wilkes MS, Kravitz RL. Advertisement-induced prescription drug requests: patients' anticipated reactions to a physician who refuses. J Fam Pract 1999 Jun;48(6):446-452. [Medline]
- Gallagher TH, St Peter RF, Chesney M, Lo B. Patients' attitudes toward cost control bonuses for managed care physicians. Health Aff (Millwood) 2001;20(2):186-192 [FREE Full text] [Medline] [CrossRef]
- Hardey M. Doctor in the house: the Internet as a source of lay health knowledge and the challenge to expertise. Sociology of Health and Illness 1999;21(6):820-835. [CrossRef]
- Anderson J. How the Internet is transforming the physician-patient relationship. Medscape Tech Med 2001;1:1-2.
- Murray E, Lo B, Pollack L, Donelan K, Lee K. Direct to consume advertising: physicians views of its effects on quality of care and the doctor-patient relationship. J Am Board Fam Pract [in press].
- . Stata Reference Manual Release 7. College Station, Texas: Stata Press; 2001.
- Wilson P. How to find the good and avoid the bad or ugly: a short guide to tools for rating quality of health information on the internet. BMJ 2002 Mar 9;324(7337):598-602 [FREE Full text] [Medline] [CrossRef]
- Eysenbach G. Consumer health informatics. BMJ 2000 Jun 24;320(7251):1713-1716 [FREE Full text] [Medline] [CrossRef]
- Eysenbach G, Diepgen TL. Towards quality management of medical information on the internet: evaluation, labelling, and filtering of information. BMJ 1998 Nov 28;317(7171):1496-1500 [FREE Full text] [Medline]
- Purcell GP, Wilson P, Delamothe T. The quality of health information on the internet. BMJ 2002 Mar 9;324(7337):557-558 [FREE Full text] [Medline] [CrossRef]
- Delamothe T. Quality of websites: kitemarking the west wind. BMJ 2000 Oct 7;321(7265):843-844 [FREE Full text] [Medline] [CrossRef]
- Gagliardi A, Jadad AR. Examination of instruments used to rate quality of health information on the internet: chronicle of a voyage with an unclear destination. BMJ 2002 Mar 9;324(7337):569-573 [FREE Full text] [PMC] [Medline] [CrossRef]
- Eysenbach G, Köhler C. How do consumers search for and appraise health information on the world wide web? Qualitative study using focus groups, usability tests, and in-depth interviews. BMJ 2002 Mar 9;324(7337):573-577 [FREE Full text] [PMC] [Medline] [CrossRef]
- Kunst H, Groot D, Latthe PM, Latthe M, Khan KS. Accuracy of information on apparently credible websites: survey of five common health topics. BMJ 2002 Mar 9;324(7337):581-582 [FREE Full text] [PMC] [Medline] [CrossRef]
- Gallagher TH, Lo B, Chesney M, Christensen K. How do physicians respond to patient's requests for costly, unindicated services? J Gen Intern Med 1997 Nov;12(11):663-668. [Medline] [CrossRef]
- Levinson W, Gorawara-bhat R, Dueck R, Egener B, Kao A, Kerr C, et al. Resolving disagreements in the patient-physician relationship: tools for improving communication in managed care. JAMA 1999 Oct 20;282(15):1477-1483. [Medline] [CrossRef]
- Young JM, Ward JE. General practitioners' use of evidence databases. Med J Aust 1999 Jan 18;170(2):56-58 [FREE Full text] [Medline]
- Pereira J, Bruera E, Quan H. Palliative care on the net: an online survey of health care professionals. J Palliat Care 2001;17(1):41-45. [Medline]
- Potts HWW, Wyatt JC. Survey of doctors' experience of patients using the Internet. J Med Internet Res 2002 Mar 31;4(1):e5 [FREE Full text] [Medline] [CrossRef]
- Lacher D, Nelson E, Bylsma W, Spena R. Computer use and needs of internists: a survey of members of the American College of Physicians-American Society of Internal Medicine. Proc AMIA Symp 2000:453-456 [FREE Full text] [Medline]
- Jadad AR, Sigouin C, Cocking L, Booker L, Whelan T, Browman G. Internet use among physicians, nurses, and their patients. JAMA 2001 Sep 26;286(12):1451-1452. [Medline] [CrossRef]
- Grzybicki DM, Vrbin CM. Pathology resident attitudes and opinions about pathologists' assistants. Arch Pathol Lab Med 2003 Jun;127(6):666-672. [Medline]
- Daneshgari F, Sorensen C. Practice pattern of urologists in the Rocky Mountains region with regard to use of urodynamic studies. Urology 2003 May;61(5):942-945. [Medline] [CrossRef]
- Duggan J, Khuder S, Sinha N, Chakraborty J. Survey of physician attitudes toward HIV testing in pregnant women in Ohio. AIDS Patient Care STDS 2003 Mar;17(3):121-127. [CrossRef] [Medline]
- Mihalynuk TV, Scott CS, Coombs JB. Self-reported nutrition proficiency is positively correlated with the perceived quality of nutrition training of family physicians in Washington State. Am J Clin Nutr 2003 May;77(5):1330-1336 [FREE Full text] [Medline]
- Murray E, Lo B, Pollack L, Donelan K, Catania J, White M, et al. The impact of health information on the internet on the physician-patient relationship: patient perceptions. Arch Intern Med 2003 Jul 28;163(14):1727-1734. [CrossRef] [Medline]
|US: United States|
Edited by G. Eysenbach; submitted 25.04.03; peer-reviewed by A Clarke; comments to author 24.06.03; revised version received 27.06.03; accepted 27.07.03; published 29.08.03
© Elizabeth Murray, Bernard Lo, Lance Pollack, Karen Donelan, Joe Catania, Ken Lee, Kinga Zapert, Rachel Turner. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 29.8.2003. Except where otherwise noted, articles published in the Journal of Medical Internet Research are distributed under the terms of the Creative Commons Attribution License (http://www.creativecommons.org/licenses/by/2.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited, including full bibliographic details and the URL (see "please cite as" above), and this statement is included.