Patient global assessment in psoriatic arthritis - what does it mean? An analysis of 223 patients from the Psoriatic arthritis impact of disease (PsAID) study

OBJECTIVE: Patient global assessment is a key outcome measure in psoriatic arthritis. To explore the meaning of patient global assessment in psoriatic arthritis by examining associations to domains of health assessed by the Psoriatic arthritis impact of disease score. METHODS: Post-hoc analysis of a multicentre cross-sectional study of patients with psoriatic arthritis. Data collection included patient global assessment, specific joint and skin global patient assessments, Psoriatic arthritis impact of disease questions covering physical (including joints and skin), psychological and social impact, and other comparator outcomes. Univariate analyses (Pearson correlation) and multivariate linear regression were performed to explain patient global assessment and the specific joint and skin global patient assessments. RESULTS: Among 223 patients (mean age: 51.0 [standard deviation, ±13.3] years; mean disease duration: 9.9 [±10.1] years; mean swollen joint count: 4.1 [±5.1]; 84.3% with current psoriasis [mainly of less than 5% body surface area]), 50.2% were females. Mean patient global assessment was 4.8 (±2.7), mean joint and skin patient assessments were respectively 5.6 (±2.5) and 4.1 (±3.0). Intraclass correlation between patient global assessment and joint or skin patient assessment was respectively 0.71 (95% confidence interval, 0.64-0.77) and 0.52 (95% confidence interval, 0.42-0.60). In multivariate analyses, patient global assessment was explained (R2 of model: 0.754) by coping (β = 0.287); pain (β = 0.240); work and/or leisure activities (β = 0.141); and anxiety (β = 0.109). CONCLUSIONS: Patient global assessment in psoriatic arthritis was explained mainly by physical, but also psychological aspects of the disease.