Evidence-based medicine: is the evidence out there for primary care clinicians?

Background: Finding evidence to answer clinical questions is essential to the practice of evidence-based medicine (EBM). However, practising EBM in primary care is thought to be problematic because of concerns about whether evidence exists to answer specific questions. Objectives: To determine the highest level of evidence per question; to ascertain the number of questions unanswered because of a lack of evidence; to establish the frequency with which guidelines answered questions; and to determine the domain of websites used to answer questions. Methods: Clinical questions were identified from two primary care answering services: ATTRACT and National Library for Health (NLH) Primary Care Answering Service. The types of evidence used to answer the question were noted, including whether this was from systematic reviews or meta-analyses (level one evidence) or from randomised controlled trials (level two). The data were collected from March to June 2008. Results: Level 1 or level 2 evidence answered 11% of questions. Sixteen per cent were unanswered because of a lack of evidence. Over 40% of questions were answered using guidelines. Forty-three per cent of questions were answered with one type of evidence and 24% with two. Conclusion: Guidelines are useful resources for primary care clinicians, answering two-fifths of questions.