Patient global assessment in psoriatic arthritis: a multicenter GRAPPA and OMERACT study

During OMERACT 8, delegates selected patient global assessment (PGA) of disease as a domain to be evaluated in randomized controlled trials in psoriatic arthritis (PsA). This study assessed the reliability of the PGA, measured by means of 0-100 mm visual analog scale (VAS), and the additional utility of separate VAS scales for joints (PJA) and skin (PSA).

In total, 319 consecutive patients with PsA (186 men, 133 women, mean age 51 ± 13 yrs) were enrolled. PGA, PJA, and PSA were administered at enrolment (W0) and after 1 week (W1). Detailed clinical data, including ACR joint count, Psoriasis Area and Severity Index (PASI), and Hospital Anxiety and Depression Scale, were recorded.

Comparison of W0 and W1 scores showed no significant variations (intraclass correlation coefficients for PGA 0.87, PJA 0.86, PSA 0.78), demonstrating the reliability of the instrument. PGA scores were not influenced by patient anxiety or depression, but were dependent on PJA and PSA (p = 0.00001). PJA was dependent on the number of swollen and tender joints (p < 0.00001). PSA scores were influenced by the extent of skin psoriasis and by hand skin involvement (p = 0.00001). Joint and skin disease were found not to correlate in terms of disease activity as evidenced by the swollen joint count compared to PASI (r = 0.11) and by the PJA compared to PSA (r = 0.38).

PGA assessed by means of VAS is a reliable tool related to joint and skin disease activity. Because joint and skin disease often diverge it is suggested that in some circumstances both PJA and PSA are also assessed.