Baseline relationships between psoriasis and psoriatic arthritis: Analysis of 221 patients with active psoriatic arthritis

Objective. To determine differences in disease onset, extent, and manifestations of psoriasis among patients with active, inflammatory psoriatic arthritis (PsA), and to examine relationships that may exist between psoriasis and PsA. Methods. Baseline demographic, clinical, and laboratory data were analyzed from 221 patients enrolled in a multicenter cooperative study, and relationships between measures of psoriasis and PsA were determined. Results. Mean percentage of body surface area (BSA) affected by psoriasis was modest (12 +/- 17), and mean severity of erythema, induration, and scaling was moderate (4.9 +/- 2.1 on a 0-9 scale). Spanish Americans tended to have a higher mean percentage of BSA (18.5%) than Caucasians (11%; p = 0.067), as well as higher target lesion severity (5.55 vs 4.84; p = 0.077). Patients with psoriatic nail disease (180/221, 81%) had significantly greater number of involved distal interphalangeal (DIP) joints (p = 0.004), There were no other significant associations of skin pattern or regional involvement with PsA. Conclusion. Patients with active PsA have generally mild skin disease, and baseline relationships between psoriasis and PsA tend to be weak except for nail involvement and DIP joint activity.