In reply
In a letter regarding our evidence-based medicine commentary1 about a clinical trial by Gisondi et al,2 Rajpara and Feldman highlight the issue of poor adherence to treatment. Researchers should consider patient adherence when interpreting trial results in regard to both internal and external validity. In the trial by Gisondi et al, if patients were not adherent to the prescribed intervention, the beneficial effect of the overall approach might have been underestimated. More importantly, adherence is likely to be optimized in the highly artificial setting of a clinical trial, and therefore the efficacy of an intervention as measured by a trial is likely to overestimate the effectiveness of the same intervention in clinical practice, especially if adherence to the regimen is a major issue. Factors that may improve adherence include educational interventions and simplification of treatment regimens.3- 5