The hf-PGA is a valid and reliable measure of hand/foot psoriasis severity in adults: results from a phase 2b clinical trial

The objective was to investigate the reliability, validity, and meaningful change scores for the Physician's Global Assessment of Hands and/or Feet (hf-PGA), a measure of clinician-reported psoriasis severity on the hands/feet. Baseline, Week 8, and Week 16 data were analyzed from adult patients with moderate to severe plaque psoriasis (n = 99) in a Phase 2b multicenter, randomized, placebo-controlled, dose-ranging study (NCT05223868). The hf-PGA had high test-retest reliability between Weeks 8 and 16 in a clinically stable subgroup (r = 0.94, kappa = 0.85, percent agreement = 95.3%). Regarding validity, hf-PGA cross-sectional and change scores positively correlated with global measures of psoriasis severity (i.e. Investigator's Global Assessment, Psoriasis Area and Severity Index, and the Psoriasis Symptom and Sign Diary) and dermatological quality of life (i.e. Dermatology Life Quality Index) as hypothesized; relationships also aligned directionally (i.e. worse hf-PGA severity was associated with worse global severity and greater impact on quality of life). Anchor- and distribution-based analyses supported a hf-PGA change score of -2 as a clinically meaningful improvement. Thus, the hf-PGA demonstrated sufficient reliability, validity, and meaningful change thresholds; it is suitable for use in clinical studies and is fit-for-purpose for evaluating psoriasis severity on the hands/feet.