Evidence-based practice (EBP) has been defined as the “integration of best research evidence with clinical expertise and patient values.”1 Though a laudable ideal, it is not feasible for individual clinicians to review, interpret, and apply all relevant evidence all of the time. Hence, clinicians should have access to “a set of tools and resources for finding and applying current best evidence from research for the care of individual patients.”2 The goal of clinical guideline writers is to perform part of this role, but they also must resolve these practical challenges if they are to provide tools to help clinicians deliver real evidence-based practice.3^–4 Here we consider some challenges for guideline writers when producing clinical advice that meets the demands of busy clinicians.

INTERPRETATION AND APPLICATION OF EVIDENCE

Knowledge to support decision making may be derived from published research, locally generated data, clinician experience, the law, and patient perspectives. Each can be regarded as “supporting evidence,” and so sometimes confusion arises in discussions about evidence and EBP. For treatment evaluation, quantitative research evidence (in particular from randomised clinical trials [RCTs] and systematic reviews of RCTs) generally has primary importance over other forms of evidence.5 But evidence from well conducted studies alone rarely provides answers to all questions in a particular clinical situation. Hence, giving best advice requires us to extrapolate and integrate the evidence to meet the demands of everyday clinical practice. This process requires interpretation and judgment.

To be of value to a clinician, trials must be up-to-date and valid and have used clinically relevant doses, patients, comparators, end points, and durations.6 Interpreters of these trials must reconcile conflicting results and take into account publication bias, reviewer bias, and relevance to current practice.7^–9 They must check that clinically important details are not hidden, overlooked, or …