[Design and validation of a questionnaire to measure treatment satisfaction in patients with moderate-to-severe psoriasis: the NEODERMA study]

Abstract

Background and objectives: the aim of this study was to design and assess the validity, reliability, and sensitivity to change of the Spanish Satisfaction With Treatment of Psoriasis Questionnaire (SSTPQ) for use in patients with moderate-to-severe psoriasis.

Patients and methods: a prospective, multicenter, observational, naturalistic study was designed. The instrument consisted of 12 items scored on a 5-point Likert scale with scores from 0 (very satisfied) to 5 (very unsatisfied), generating a total score of 0 to 48. Patients completed the questionnaire at baseline and then at 3-, 6-, 9-, and 12-month follow-up. At each visit, data were also collected on the Psoriasis Area and Severity Index (PASI), treatment adherence (Morisky-Green questionnaire), and overall treatment satisfaction on a Visual Analogue Scale (VAS) from 0 to 100.

Results: a total of 423 patients were included in the study and 68% completed 12 months of follow-up. Responses were provided to all items in 98.8% of cases. There was a weak correlation between changes in treatment satisfaction on the SSTPQ and changes in PASI score (r = 0.38 to 0.33); in contrast, there were strong correlations with changes in the VAS score for overall treatment satisfaction (r = -0.75 to -0.81). Good internal consistency was observed (Cronbach α = 0.92). The intraclass correlation coefficient was 0.89, with a mean difference in score at 3- and 6-month follow-up of 0.07.

Conclusions: The results obtained suggest that the SSTPQ is a feasible, valid, and reliable tool for the assessment of treatment satisfaction in patients with moderate-to-severe psoriasis.