Background: Self-report measures are the most used methodologies for the evaluation of adherence to psoriasis topical treatment, although currently there is no standard questionnaire for this purpose.
Objective: The present study aimed at developing a novel questionnaire (Questionnaire for Adherence to TOPical treatment [QATOP]) for the assessment of adherence to topical treatment in psoriasis.
Methods: A questionnaire containing nine items organized into two parts (part 1: current patient treatment; part 2: adherence to treatment, amount used, and treatment-associated variables) was developed, supported by a systematic literature review, qualitative patient focus interviews, and expert-group input. Its content validity was determined by a pilot study of six patients. Adherence to topical treatment was then assessed in 35 patients with psoriasis, after 45 days of treatment, using the QATOP and a medication log. Associations between different items of the QATOP and the log were investigated.
Results: Adherence results were 63.5 ± 29.2% for the log and 60.9 ± 24.4% for the QATOP, and were strongly correlated (R = 0.819, p < 0.001). Distinct posologic regimens were reported by patients, which, in some cases, were not the usual doses. Patients also reported using doses of medicine on each application that were markedly lower than required.
Conclusion: The QATOP is a valid and reliable self-report measure of adherence to topical treatment in patients with psoriasis. The use of this standard questionnaire could improve the methodological quality of adherence studies. Improvement of the clarity of posologic instructions is clearly urgently needed.