“…Known-groups validity was assessed using baseline DLQI score categories (total scores of 2-10, 11-20, or 21-30); mean PSI item scores and standard deviations (SDs) were calculated for each DLQI category, and one-way analysis of variance was used to compare groups. Ability to detect change was examined using PtGA as anchor; mean PSI total scores and SDs were calculated for patients with PtGA worsening by ‡1 point, no change in PtGA, or improvement in PtGA by ‡1 point, and the F test using repeated measures analysis of covariance (adjusted for body mass index, age, gender, and disease duration) (14) was used to compare groups. Exploratory factor analyses were conducted to examine the measurement model.…”