Can physician's self-estimates be used as a valid instrument to determine prescription frequencies of anti-psoriatic drugs? Comparison of the results of a cross-sectional study using self-estimates with actual prescription behavior documented in a cohort study.

ABSTRACT

PURPOSE: Physicians' self-estimates of their own prescription behavior can be used as a tool to gather information on prescription frequencies. Self-estimates as a tool for health-care research on prescription frequencies need to be validated as a suitable method before it can be used widely. METHODS: We performed a cross-sectional study inviting all dermatologists in Berlin and Brandenburg to give self-estimates of their own prescription behavior of anti-psoriatic drugs. The results were compared with the results from a consecutive 8-months cohort study with the same participants documenting their actual treatment choices during every visit of a psoriasis patient on a standardized documentation sheet. Differences between self-estimates and documented prescription patterns were analyzed with respect to systemic anti-psoriatic drugs and UV treatment. RESULTS: Fifty-one dermatologists participated. They documented an average of 91 patient visits each. Absolute differences between the self-estimates and the documented actual prescription behavior ranged from -2.5% to 1.4% for systemic treatments. For psoralen plus ultravioloet A (PUVA) treatment, the absolute difference was 3.3% and for ultraviolet B (UVB) 4.7%. CONCLUSIONS: Self-estimates were surprisingly exact. Self-estimates may be suggested as one tool to assess prescription frequencies, but further studies are needed to confirm their validity.