Physician’s Global Assessment Reliable for Evaluating Disease Activity in Psoriatic Arthritis

Use of the physician’s global assessment (PGA) of disease activity in patients with psoriatic arthritis (PsA), as measured with a 0- to 100-mm visual analog scale (VAS) and separate VAS scales for musculoskeletal (PhysMSK) and dermatologic (PhysSk) disease manifestations, are reliable tools for the evaluation of musculoskeletal and dermatologic disease activity, according to the results of the multicenter Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) study. Findings from the analysis were published in The Journal of Rheumatology.

A total of 17 centers from 8 countries enrolled 319 consecutive patients with PsA. Overall, 58% of the participants were men and the average patient age was 51±13 years. All participants received PGA, PhysMSK, and PhysSk evaluation forms at enrollment and after 1 week. Patients recorded their clinical data in terms of musculoskeletal disease manifestations and dermatologic symptoms.

For MSK involvement, the median number of tender joints was 5 and the median number of swollen joints was 1. Axial involvement was observed in 8% of patients, dactylitis in 7%, and enthesitis in 21%. Regarding skin involvement, median Psoriasis Area and Severity Index (PASI) score was 2.8 in the overall patient cohort and 4.0 in the single dermatology unit.

When findings at enrollment and 1 week were compared, scores revealed no significant variation. The intraclass correlation coefficients were 0.87 for the PGA, 0.86 for the PhysMSK, and 0.78 for the PhysSk, which confirmed the reliability of the instruments. Scores on the PGA were significantly dependent on PhysMSK and PhysSk scores (P <.0001), with a major effect reported with the musculoskeletal components for PhysMSK (β=0.69; 95% CI, 0.64-0.74) vs PhysSk (β=0.32; 95% CI, 0.27 to 0.37). This demonstrates that the musculoskeletal component is recognized as the main clinical concern compared with dermatologic manifestations.

PhysMSK scores were significantly associated with the number of swollen joints, tender joints, and the presence of dactylitis (P <.0001). PhysSk scores were significantly associated with the extent of skin psoriasis and with face, buttocks or intergluteal, and feet involvement (P <.0001).

The investigators concluded that the use of PGA scores for assessment of disease activity in individuals with PsA may deviate from patient self-evaluation. They suggest that both PhysMSK and PhysSk scores be used in the assessment of disease activity, since musculoskeletal and skin or nail disease activity manifestations may vary.

Reference

Cauli A, Gladman DD, Mathieu A, et al; the GRAPPA 3PPsA Study Group. Physician’s global assessment in psoriatic arthritis: a multicenter GRAPPA Study [published online June 15, 2018]. J Rheumatol. doi:10.3899/jrheum.171183