The nexus of evidence, context, and patient preferences in primary care: postal survey of Canadian family physicians

Background Evidence-based medicine is gaining prominence in primary care. This study sought to examine the relationships among family physicians' attitudes toward EBM, contextual factors, and clinical decision-making and to investigate the factors that contribute to 'contrary to evidence' clinical decisions. Methods A postal survey mailed to a random sample of Canadian family physicians, stratified by age, gender, and practice setting. The main outcome measures were respondents' attitudes toward evidence-based medicine and preferred treatment option in four simulated clinical scenarios with wording randomly varied. Results Canadian family physicians report positive attitudes toward EBM, believe that EBM improves patient care, and agree that research findings are useful in the day-to-day management of patients. The scenario study showed that physicians were strongly influenced by a patient demanding/requesting either a screening test (adjusted Odds Ratio [OR] 5.15, 95% confidence interval [CI] 2.9 to 9.2 for demand mammogram; adjusted OR 3.11, 95% CI 1.7 to 5.6 for request mammogram) or a diagnostic test (adjusted OR 3.95, 95% CI 2.1 to 7.5 for demand lumbar spine x-ray; adjusted OR 2.08, 95% CI 1.1 to 4.1 for request x-ray). This relationship did not hold for the treatment scenario (prescribing antibiotics for acute bronchitis) where hours of practice (adjusted OR 3.5, 95% CI 1.1 to 11.7 for 50+ hours practice; adjusted OR 1.79, 95% CI 1.0 to 3.2 for 20–49 hours practice) and type of practice (adjusted OR 2.22, 95% CI 1.3 to 3.7 for solo practice) were significant. 80% of respondents reported teaching breast self-examination with female physicians twice as likely as males (adjusted OR 2.11, 95% CI 1.2 to 3.8). Conclusions Canadian family physicians are favourably disposed to the precepts of evidence-based medicine; however, patient expectations and practice characteristics can influence physicians such that decisions are taken that are broadly contrary to evidence. Recently revised models of EBM emphasizing the importance of patient preferences and the clinical context appear to reflect more accurately the clinical reality of primary care physicians.


Background
Ten years after its debut, evidence-based medicine (EBM), though still controversial, has become an accepted and integral component of health care practice [1]. Despite its widespread dissemination and adoption, however, the impact of EBM in primary care is decidedly complex [2,3] and remains poorly understood [4], especially regarding the interaction of research evidence with the myriad contextual factors that characterize the primary care setting.
One such factor, the doctor-patient relationship, is increasingly recognized as fundamental to the provision of quality primary care services. The focus of a number of current health policy efforts such as the "concordance initiative" [5] and the "expert patient programme" [6] attest to this fact. Likewise, in the arena of health care research, there is continuing development of theoretical models explicating the complex, multi-faceted nature of the doctor-patient relationship. A substantial and growing body of literature emphasizes the significant (often under-estimated) influence of various patient-and physician-related factors on clinical decision-making in primary care [7][8][9].
Despite this progress, however, the long-running debate regarding the feasibility and suitability of implementing an evidence-based approach in primary care rages on. Indeed, there is increasing concern that the central assumptions of the EBM movement are at odds with the core principles of primary care [10], particularly that of patient choice [11,12]. To our knowledge, there have been no published studies reporting statistical modelling of the association of attitudinal and contextual factors with the clinical decision-making of primary care providers. Thus, the specific objectives of this study were: a) to examine the relationships among physician attitudes toward EBM, contextual factors, and clinical decision-making in primary care; and b) to investigate the factors that contribute to 'contrary to evidence' clinical decisions.

Participants and setting
This paper reports on the quantitative component of a larger multi-methods research project based in the Primary Care Research Unit at Sunnybrook & Women's College Health Sciences Centre in Toronto, Canada. (The qualitative component has been published separately [13]). In the spring of 2002 we conducted a cross-sectional postal survey of primary care physicians across Canada. The sampling frame, which was provided by the College of Family Physicians of Canada (CFPC), comprised a computer-generated random list of 1134 family physicians. The inclusion criteria required that the physician be a Certificant of the College of Family Physicians (CCFP) and in active practice at the time of study. The sample was stratified to reflect the age, gender, and rural/ urban composition of the CFPC membership (n = 15,000). The study was approved by the Research Ethics Board of the University of Toronto.

Survey instrument
The survey instrument, which was pilot-tested with physicians and health services researchers, was a 4-page penciland-paper questionnaire with four main sections. The first section comprised 10 Likert-type items measuring physicians' attitudes toward the practice of EBM in primary care. These 10 items were adapted from a British postal survey of general practitioners [14], whereas the remainder of the questionnaire was developed by the authors for the purposes of the present study. The second section listed a number of contextual factors, such as co-morbidity and the prestige of the patient in the community, for which respondents indicate the likelihood that each would influence their decision to prescribe a particular diagnostic test or treatment. In the third section, respondents were presented with a forced-choice option in four simulated clinical scenarios/case vignettes (see Additional File 1 -Clinical Scenarios). Three versions of each scenario were written such that the patient variously "wondered about," "requested," or "demanded" the test/treatment in question; the mailing was counterbalanced with one-third of the target sample randomly receiving each of the three versions. The final section of the questionnaire asked respondents to supply typical demographic information.

Data collection and analysis
In order to ensure stable estimates in multiple regression analysis, a minimum of 15 data points per predictor is preferred [15]. Assuming a response rate of approximately 50%, we estimated that no fewer than 400 completed questionnaires would be required. On this basis, the initial survey package was mailed to a total of 1134 family physicians. Along with the questionnaire, the package contained a personalized cover letter, a stamped return envelope, and a reply postcard. (The inclusion of the latter was necessitated by the fact that no identifying marks appeared on the questionnaire itself; the reply postcards were to be returned separately from the questionnaire in order to indicate intentions regarding participation in the study.) Non-respondents were sent postcard reminders at 4 weeks and again at 8 weeks. At 12 weeks, residual nonrespondents received a second letter accompanied by a replacement copy of the questionnaire. Data were entered into a spreadsheet for statistical analysis using SAS 8.2.

Results
There were 97 deletions from the 1134 in the original target sample: 63 were not practicing family medicine, 23 had moved (incorrect mailing address), and 11 were retired or on leave of absence. Of the remaining 1037 questionnaires, a total of 431 (42%) were completed and    (9)  6 (1) 3 (1) EBM is of limited value in general practice because much of primary care lacks a scientific base.
We performed logistic regression analyses to investigate potential factors influencing the decision-making of family physicians responding to the clinical scenarios. Four factors were significant: patient expectations, physician gender, type of practice (solo versus group), and hours per week seeing patients. Table 4 presents the adjusted odds ratios for preferred treatment options associated with these four factors. Respondents who received versions of Scenario 1 in which the patient was either 'requesting' or 'demanding' a screening mammography (as opposed to simply 'wondering' about it) were significantly more likely to offer the screening. Likewise, in Scenario 2, the odds ratio was raised significantly when the patient either 'requested' or 'demanded' an x-ray of the lumbar spine. By contrast, in Scenario 3, the odds ratio was not raised significantly when the patient 'requested' or 'demanded' antibiotics for her bronchitis; in this case, the odds of antibiotics being prescribed were significantly increased for physicians in solo practice and for those reporting higher number of hours per week seeing patients. Finally, in Sce-nario 4, female family physicians were significantly more likely to report teaching BSE than were their male counterparts.

Discussion
The results of this national survey indicate that the great majority of Canadian primary care physicians hold positive attitudes toward EBM and its application in family medicine. At the same time, however, there is evidence that a sizeable proportion of these physicians make clinical decisions that could be regarded as contrary to evidence and that such decisions are influenced by patient expectations and practice characteristics. Taken together, these findings, while underscoring the complexity of the doctor-patient relationship, further suggest the presence of a disconnect between physician attitudes and day-today clinical practice.
We believe these to be the first published data to report on the relationships among physicians' attitudes toward EBM, contextual factors, and clinical decision-making. The strengths of this study are its national scope and a representative sample stratified for age, gender, and rural/ urban split. Our final response rate of 42% is somewhat low. While non-response is an important potential source of bias in survey research, a low response rate does not necessarily degrade the validity of the data [16]. Sampling bias can be predicted, tested for, and corrected [17]. Evaluation research suggests that representative samples can be achieved without a high response rate; moreover, high response rates are considered less important for homogeneous samples responding as members of a professional group on matters of concern to them (such as with physicians surveyed on medical care issues) than for heterogeneous samples responding as individuals [18]. Present concerns regarding sampling bias and low external validity should be assuaged by the fact that our achieved sample does not differ significantly from the target sample on important demographic factors (age, gender, and practice setting); however, the possibility remains that nonrespondents could differ from respondents in other respects, such as degree of reflexivity in clinical practice, model of medical training program, etc. This notwithstanding, we maintain that we achieved a random sample of a random sample and therefore that these results are representative of family physicians in Canada.
We acknowledge that the clinical case vignette/simulated scenario cannot capture the breadth and complexity of actual physician behaviour. At the same time, however, the validity of this method has been demonstrated in a recent comparative evaluation study, in which the authors concluded: "Vignettes appear to be a valid and comprehensive method that directly focuses on the process of care provided in actual clinical practice" [19]. Moreover, the myriad associated advantages of the clinical vignetteconvenience, low cost, absence of observer effect, ease of variable manipulation -contribute to its continuing widespread use as a data collection tool [20].
Our finding that Canadian family physicians hold positive attitudes toward the promotion of EBM in primary care is consistent with the findings of similar surveys in the United Kingdom [14] and Saudi Arabia [21], both of which used a similar survey instrument to that employed in the present study. The median value for the estimated percentage of respondents' clinical practice that is considered to be evidence-based was 60%, which falls midway between the finding of 50% in the UK [14] and the 68% reported for Saudi Arabia [21].
Despite the highly favourable attitudes toward EBM, fully one-third of respondents rated their clinical practice to be only 20%-40% evidence-based. Moreover, as indicated by the responses to our four clinical scenarios, a sizeable proportion of family physicians appear to make clinical decisions that could be considered contrary to evidence. The data also show that the clinical decision-making of family physicians is strongly impacted by contextual factors such as patient expectations, thereby lending support to the findings of the qualitative component of our project which indicated that patient factors exert a powerful influence on physician behaviour and can serve as trumps to research evidence [13].
In Scenarios 1 and 2, patients who requested or demanded the screening/diagnostic test were significantly more likely to receive it, indicating that patient expectations profoundly influence clinical decisions and can result in decisions potentially at odds with research evidence. The salience of patient factors has been previously demonstrated in a number of studies examining the doctor-patient relationship [7][8][9]. That patient values and expectations so powerfully affect clinician behaviour has tremendous implications given that patient views are shaped strongly by forces other than physicians and health care providers, most notably the media [22] and increasingly the internet [23]. As patient views can be manipulated, and may be informed by less than authoritative sources, it is important for family physicians to be conscious of these forces on their practice patterns. Earlier investigations have indicated that physicians' perceptions of patients' expectations are the strongest predictor of prescribing behaviour and that the writing of non-indicated prescriptions is primarily associated with the physician's sense of feeling pressured [24,25]. Further research is required to understand why family physicians acquiesce in the face of patient expectations that could be regarded as contrary to evidence. Given that the management of competing pressures -patient demands, time constraints, limited resources -is a daily challenge for family physicians, the development of tools to assist clinicians in this regard might prove helpful. As has been noted elsewhere, however, the development of such decision aids is complicated by the presence of conflicting or unclear evidence [22].
Patient expectations did not seem to influence treatment decisions (Scenario 3) as they did with respect to screening and diagnostic decisions (Scenarios 1 and 2). Rather the results suggest that family physicians in solo practice and those reporting higher hours per week seeing patients are significantly more likely to prescribe antibiotics than those in group practice and those reporting lower hours per week seeing patients. This is consistent with prior research that points to a significant relationship between certain practice characteristics (including number of practice days and number of patients per day) and prescribing behaviour [26].
Surprisingly, despite the downgrading of routine instruction of BSE to a 'Grade D' in 2001 [27], the results for Scenario 4 show that most primary care physicians in Canada report still teaching BSE to their female patients. This finding is strikingly at odds with the self-perception of these family physicians as being influenced by and adherent to the precepts of EBM. We do not believe that this finding can be explained by clinicians simply not knowing of the evidence. A recent study of Canadian family physicians indicated that while the great majority (89%) are aware of the new BSE recommendations, very few (16%) have changed their usual practice of routinely teaching BSE [28]. We know that research evidence does not often readily translate into changed patient management [29,30]; indeed, primary care physicians are often reluctant to change their practice in light of new evidence, especially on the basis of a single study [4]. With respect to BSE, physicians may believe that this new evidence (i.e., the Grade D recommendation) is not credible, not applicable to their patients, and/or in need of either supporting evidence from additional studies or endorsement from professional organizations. That female family physicians are significantly more likely to teach BSE than males is consistent with prior research on gender differences in practice styles [31][32][33]; that such a high percentage overall are not adhering to the new BSE recommendations suggests the need for further studies devoted to determining what constitutes credibility in evidence.

Conclusions
The results of this study indicate that Canadian family physicians earnestly believe in the value of research evidence and are extremely receptive to the promotion of EBM in primary care. On the other hand, the clinical context and patient expectations remain tremendously important factors in the clinical decision-making process of family physicians -to the extent that decisions are taken that are broadly contrary to evidence. Thus, it appears that the reality of clinical practice in primary care is still removed from the goals of EBM; indeed, the present findings strengthen the argument that the central assumptions of EBM may not be compatible with the core principles of primary care [10].
We conclude that this study provides empirical support to recent revisions to the EBM model of clinical decisionmaking that places increased emphasis on patient preferences and the clinical context [34]. It is important to bear in mind that the present findings do not report on observations of actual clinical behaviour, but rather on physicians' responses to simulated clinical scenarios, which do not by any means exhaust the possible ways in which diagnostic and treatment decisions can be influenced by patient expectations and other contextual factors. The results do, however, raise a number of important issues that require further consideration by the medical profession.
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