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

Objective. To determine differences in disease onset, extent, and manifesta tions of psoriasis among patients with active, inflammatory psoriatic arthr itis (PsA), and to examine relationships that may exist between psoriasis a nd PsA. Methods. Baseline demographic, clinical, and laboratory data were analyzed from 221 patients enrolled in a multicenter cooperative study, and relation ships between measures of psoriasis and PsA were determined. Results. Mean percentage of body surface area (BSA) affected by psoriasis w as modest (12 +/- 17), and mean severity of erythema, induration, and scali ng was moderate (4.9 +/- 2.1 on a 0-9 scale). Spanish Americans tended to h ave 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). Pati ents with psoriatic nail disease (180/221, 81%) had significantly greater n umber of involved distal interphalangeal (DIP) joints (p = 0.004), There we re no other significant associations of skin pattern or regional involvemen t 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.