Author Affiliations: Center for Dermatology Research, Departments of Dermatology (Mr Davis and Dr Feldman). Pathology (Dr Feldman), and Public Health Sciences (Dr Feldman), Wake Forest School of Medicine, Winston-Salem, North Carolina.
In their very interesting and well-powered analysis, Gelfand et al1 comment on the phenomenon of systemic treatments for psoriasis showing greater efficacy in clinical trials than in clinical practice. Many reasons for better efficacy in clinical trials are theorized, including different patient populations, more variation in the character of the disease, comorbidities, and differences in raters or rating standards. Another likely cause for better outcomes in clinical trials is that adherence to dermatological treatment is higher in clinical trials than in clinical practice.
Davis SA, Feldman SR. Using Hawthorne Effects to Improve Adherence in Clinical Practice: Lessons From Clinical Trials. JAMA Dermatol. 2013;149(4):490-491. doi:10.1001/jamadermatol.2013.2843