Evidence-based clinical guidelines: a new system to better determine true strength of recommendation

Clinical practice guidelines often grade the 'strength' of their recommendations according to the robustness of the supporting research evidence. The existing methodology does not allow the strength of recommendation (SOR) to be upgraded for recommendations for which randomized controlled trials are impractical or unethical. The purpose of this study was to develop a new method of determining SOR, incorporating both research evidence and expert opinion.

A Delphi technique was employed to produce 10 recommendations for the role of exercise therapy in the management of osteoarthritis of the hip or knee. The SOR for each recommendation was determined by the traditional method, closely linked to the category of research evidence found on a systematic literature search, and on a visual analogue scale (VAS). Recommendations were grouped A-D according to the traditional SOR allocated and the mean VAS calculated. Difference across the groups was assessed by one-way ANOVA variance analysis.

Mean VAS scores for the traditional SOR groups A-D and one proposition which was 'not recommended' showed significant linearity on one-way ANOVA. However, certain recommendations which, for practical reasons, could not assessed in randomized controlled trials and therefore could not be recommended strongly by the traditional methodology, were allocated a strong recommendation by VAS.

This new system of grading strength of SOR is less constrained than the traditional methodology and offers the advantage of allowing SOR for procedures which cannot be assessed in RCTs for practical or ethical reasons to be upgraded according to expert opinion.