Validation of DermSat-7 for Assessing Treatment Satisfaction in Patients With Psoriasis.

Abstract

Importance: A critical need exists for developing a validated dermatologic-specific treatment satisfaction instrument.

Objective: To evaluate the structural validity, internal consistency, construct validity, and test-retest reliability of the 7-item dermatology-specific treatment satisfaction (DermSat-7) instrument in patients with psoriasis.

Design, setting, and participants: This survey study was conducted from July 2020 to April 2023 in dermatology outpatient clinics at the University of Southern California, Brigham and Women's Hospital, and Mount Sinai Union Square and included adults (aged ≥18 years) with psoriasis who were fluent in English. On day 1, the clinician at the study sites assessed psoriasis disease severity in person using the Psoriasis Area and Severity Index (PASI), body surface area (BSA), and Physician Global Assessment (PGA). On day 1, study participants completed the DermSat-7, the generic 9-item Treatment Satisfaction Questionnaire for Medication (TSQM-9), and the Dermatology Life Quality Index (DLQI). They also answered demographic questions and reported their own disease severity using the Patient Global Assessment (PtGA). On day 14 (±2 days), the patient then completed the DermSat-7 and PtGA a second time.

Main outcomes and measures: The DermSat-7 is a 7-item self-administered instrument with a recall period of 14 days that assesses patient satisfaction with their treatments across various inflammatory dermatology diseases, including psoriasis. Construct validity, structural validity, internal consistency, and test-retest reliability of DermSat-7 were assessed as defined by the Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) taxonomy and reported following the COSMIN reporting guideline for studies on measurement properties.

Results: The analysis included 142 patients with psoriasis (mean [SD] age, 51.1 [15.5] years; 77 males [54.2%]). Exploratory factor analysis and confirmatory factor analysis supported the unidimensionality of the DermSat-7 domains. The internal consistency of the effectiveness and convenience domains was high with a Cronbach α of 0.88 and 0.81, respectively. Regarding construct validity, differences between groups based on PASI/PGA scores were aligned with preexisting hypotheses, and the correlations between DermSat-7 and TSQM-9 subscores were strong to very strong (ρ = 0.75 for effectiveness; ρ = 0.66 for convenience; and ρ = 0.70 for overall satisfaction; all P < .001). Intraclass correlation was 0.85, indicating high test-retest reliability.

Conclusions and relevance: This survey study found that the DermSat-7 may be a valid and reliable instrument for measuring treatment satisfaction in patients with psoriasis.