Introduction

Even though the use of systematic research has deep roots in the history of medicine, the concept “evidence based medicine” (EBM) was first introduced in 1991 by Gordon Guyatt [1]. In 1996 Sackett described EBM as “the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients” and practicing evidence based medicine means “integrating individual clinical expertise with best available external clinical evidence from systematic research” and “the […] compassionate use of individual patients' predicaments, rights and preferences in making decisions about their care” [2]. By definition, Sackett states that EBM is the integration of three important aspects: current best evidence, clinical expertise and patients' values.

The ideological background for EBM has been credited to the Scottish epidemiologist Archie Cochrane (1908–1988) [3] who has been honoured through the naming of evidence-based medical research centres — Cochrane Centres — and an international organization, the Cochrane Collaboration. EBM has rapidly gained international attention and acceptance. Countless activities are denoted evidence-based and it may be hard to read a medical journal without coming across the term EBM. While Medline/PubMed did not contain the term EBM until 1992, the total number of hits for the term in March 2009 was 34 918.

Still, EBM has been met with questions and criticism. What is really meant by EBM [4]–[9]? What is the strict scientific proof that randomised controlled trials entail less bias than other study designs [7], [10]–[12] or that they improve patients' health [10], [12]–[15]? Others see EBM as scientification of the art of medicine (“cook book medicine”) or point to the evangelical tone of some EBM advocates [11], [13], [16].

Whether physicians endorse the EBM principles and apply them in their clinical practice is still largely unknown. Several studies point to problems with implementing EBM in clinical practice (e.g. institutional culture, lack of time, lack of information resources, impediment of clinical freedom) [15], [17]–[20]. Studies from Denmark [20] and Australia [21] indicate that textbooks and colleagues are consulted more often than the Cochrane Library.

With this background we designed a study to elucidate Norwegian physicians' opinions and experiences with EBM. Norway has a population of 4.8 million and is number two worldwide in terms of health care expenditure per capita [22]. We specifically aimed to address the following research questions:

• Do Norwegian physicians know the three key aspects of EBM?
• Do they practice EBM methods in their clinical practice?
• What are their attitudes to EBM?
• Has EBM in their opinion changed medical practice?
• What are important information sources in clinical practice?

Materials and Methods

Data for this study stems from the so called Reference Panel of the Norwegian Physician Survey, approximately 1400 doctors of all specialties and work situations who receive a postal questionnaire from The Research Institute of The Norwegian Medical Association every other year. The questionnaires contain both questions that are repeated every time, and questions that change from one round to the next, often to meet the need of external collaborators. In 2006, a 15-page questionnaire was sent to the 1,400 professionally active panel members. It included seven composite questions about EBM with a total of 27 items. These items were sent to several colleagues in Norway and the UK for pilot testing. Most of these 27 items were formulated as statements about which respondents could indicate their position on a five point Likert scale from 1 (completely disagree) to 5 (completely agree).

The 44 officially recognized medical specialties in Norway were divided into eight groups (Table 1). Doctors in training were categorized according to their future specialty.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 1. Background data on the respondents compared with the total Norwegian doctor work-force in 2006.

https://doi.org/10.1371/journal.pone.0007828.t001

Frequency tables and cross tables between single response variables and various groups of doctors with χ²-test were primarily used in this presentation. Violin-plots, a modification of box-plots where the density of the data is also shown (Hintze, J 2008. NCSS, NCSS LLC, Kaysville, Utah, USA www.ncss.com), are used to show various sources of information in clinical practice. We also used principal component analysis for a more comprehensive description of the doctors' attitudes towards EBM, and ANOVAs of group differences on the principal components (Table 2).

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 2. Three principal components of attitudes towards EBM.

https://doi.org/10.1371/journal.pone.0007828.t002

Results

In total 976 out of the 1,400 physicians (70%) returned a questionnaire, of which 10 were unusable. Among non-respondents, 50 explicitly stated that they did not wish to participate while 374 did not return the questionnaire despite one reminder. The respondents were quite representative of all Norwegian doctors with regard to gender, age and specialty, with slightly more psychiatrists and slightly less public health specialists (Table 1).

Attitudes towards EBM

80% of the respondents agreed that “EBM helps physicians towards better practice” and 52% agreed that it “improves patients' health” (Table 3). On the other hand, 54% indicated that it is difficult to search for evidence in a busy practice. For most of the attitude questions, including the statements about EBM and health authorities, pharmaceutical industry, cost containment and patient values, the majority neither strongly agreed nor disagreed.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 3. Frequency distributions on ten statements about EBM.

https://doi.org/10.1371/journal.pone.0007828.t003

For a closer analysis of attitudes towards EBM the 10 statements in Table 3 plus the statement “Cochrane reviews are the most reliable” were entered into a principal component analysis yielding three components with eigenvalue over 1, as shown in Table 2. We named the components indifferent, positive and negative, and Figure 1 shows how the different categories of doctors in the study differ with regard to these three components. The most positive group is the junior hospital doctors, who score significantly higher on “positive” than their senior colleagues. The least positive were the private specialist practitioners. Interestingly, the general practitioners score significantly higher than the grand mean on all three composite variables.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Figure 1. Group differences in the three identified principal components of attitudes towards EBM.

Means with 95% confidence intervals. Circle – Indifferent. Square – Positive. Triangle – Negative.

https://doi.org/10.1371/journal.pone.0007828.g001

Information sources in clinical practice

The most frequently reported information sources (score 4 or 5) for making decisions about individual patients' health were “colleagues” (86%), “other specialists one trusts” (78%) and “medical textbooks” (76%). In total 56% and 52% reported “Medline/Pubmed” and “International medical journals”, respectively, while 27% indicated “the Cochrane database”. While the use of textbooks and colleagues varied little across physician groups, there was considerable variation with respect to international medical journals and the Cochrane Library (Figure 2).

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Figure 2. Violin plots (box plots) of responses to the use of some of the information sources in medical practice by job category.

The red dots represent medians, the thick blue vertical lines the interquartile range and the yellow areas the general distribution of responses. The question was: “If you need information for the treatment of a patient, which source would you use?” Likert scale from 1 (never) to 5 (often). A - Junior hospital doctors. B - Senior hospital doctors. C - General practitioners. D - Private practice specialists. E - Other doctors.

https://doi.org/10.1371/journal.pone.0007828.g002

Discussion

The results of this study indicate that Norwegian physicians have positive attitudes to EBM although their knowledge of all of its three main components (research evidence, physician expertise and patient values) is limited. They do not consider EBM to be an important factor for change in medical practice, and few have attended EBM courses or use the Cochrane database.

Our results should be viewed in the context of the study limitations. First, the sample may not be entirely representative of Norwegian physicians, even though selection bias was limited (Table 1). Second, the respondents may have responded strategically for personal reasons. Third, we did not define the term “EBM course”, and the responses here should be interpreted cautiously. Despite these limitations, however, the study results may offer interesting insight because the response rate was fairly high and most of the items relatively simple to understand.

Even though EBM “is on everyone's lips”, relatively few studies have been published about the knowledge of and attitudes toward the concept [10], [17]–[21], [23], [24]. Our findings are mainly in line with other studies. Even though we did not focus on barriers to the use of EBM, the results indicate that one-fourth found it difficult to implement EBM in busy practices. This is similar to findings in other countries where several barriers to implementation of EBM into clinical practice were reported. McAlister [19] showed that less than half of Canadian physicians felt confident in literature search. Among disincentives to using critical appraisal of literature 49% of Australasian physicians [24] reported inability to recall specific appraisal criteria and 35% inability to record the results of appraisal for future use. Lack of training and skills of critical appraisal of literature was reported by Green [18] and Hadley [17]. Like in our study, lack of time is often a barrier for EBM. In Australia and new Zealand between 60% and 90% of the physicians have this experience [21], [24]. Lack of relevant evidence was reported by 26% of Canadian physicians [19]. Lack of knowledge about EBM related sources of information among physicians was reported by Veness [21] where just over half of respondents were aware of the Cochrane Library but did not use it. The principles of practicing EBM by a five-step model [14] have also been considered a challenge in implementation [15]. When requiring systematic reviews or meta-analysis in order to answer a clinical question, Elstein claims that “…EBM moves from the desk of the practicing clinician to that of the academic researcher…“ [25]. Also, our study confirms previous findings of low utilization of typical EBM information sources and frequent use of traditional sources [19]–[21], [23], [24]. Scott [24], Veness [21] and Oliveri [20] found that only 17 to 20% did so. Among 85% of those who claimed always to practice EBM, near half had never used the Cochrane Library [20]. In Canada [19] only 5% used the Cochrane Library on a regular basis, while 93% used clinical experience and over 60% used their colleagues as their main sources for information in making clinical decisions. We do not know about other countries, but the Cochrane database and other EBM resources have been available free of charge to health personnel in Norway since 2002 and the low use of these sources seems a bit surprising.

Most of the findings in this study probably speak for themselves, but some of them are noteworthy: First, EBM has repeatedly been defined as an enterprise based on best evidence, physician expertise and patient values [2]. In practice, physicians seem to associate EBM with research evidence, and less so with expertise and particularly little with patient values. This is not surprising, however, given the fact that the latter two aspects are vague and little pursued by EBM advocates. The lack of knowledge about EBM and difficulties in implementing it in clinical practice could explain the physicians' indifference, although the term EBM is much used and warmly embraced by many key persons in health care. Relatively few have attended EBM courses, and few see EBM as a key factor for change in medical practice.

The findings of this study may provide messages to many of us. Advocates of EBM should be careful in overvaluing the impact of EBM. Those involved with medical education should realize that they still have some way to go in teaching research principles. Sir David Weatherall proclaimed that “EBM came as a gift form the Gods” [26]. Apparently, not all physicians have received it yet.