Physician’s Global Assessment in Psoriatic Arthritis: A Multicenter GRAPPA Study

Objective. Physician’s global assessment (PGA) of disease activity is a major determinant of therapeutic decision making. This study assesses the reliability of the PGA, measured by means of 0–100 mm visual analog scale (VAS), and the additional use of separate VAS scales for musculoskeletal (PhysMSK) and dermatologic (PhysSk) manifestations in patients with psoriatic arthritis (PsA).

Methods. Sixteen centers from 8 countries enrolled 319 consecutive patients with PsA. PGA, PhysMSK, and PhysSk evaluation forms were administered at enrollment (W0) and after 1 week (W1). Detailed clinical data regarding musculoskeletal (MSK) manifestations, as well as dermatological assessment, were recorded.

Results. Comparison of W0 and W1 scores showed no significant variation (intraclass correlation coefficients were PGA 0.87, PhysMSK 0.86, PhysSk 0.78), demonstrating the reliability of the instrument. PGA scores were dependent on PhysMSK and PhysSk (p < 0.0001) with a major effect of the MSK component (B = 0.69) compared to skin (B = 0.32). PhysMSK was correlated with the number of swollen joints, tender joints, and presence of dactylitis (p < 0.0001). PhysSk scores were correlated with the extent of skin psoriasis and by face, buttocks or intergluteal, and feet involvement (p < 0.0001). Finally, physician and patient assessments were compared showing frequent mismatch and a scattered dot plot: PGA versus patient’s global assessment (r = 0.36), PhysMSK versus patient MSK (r = 0.39), and PhysSk versus patient skin (r = 0.49).

Conclusion. PGA assessed by means of VAS is a reliable tool to assess MSK and dermatological disease activity. PGA may diverge from patient self-evaluation. Because MSK and skin/nail disease activity may diverge, it is suggested that both PhysMSK and PhysSk are assessed.