Psoriasis and arthritis. II. A cross-sectional comparative study of patients with "psoriatic arthritis" and seronegative and seropositive polyarthritis: clinical aspects.

Arthritis of the terminal joints of the hands and feet occurred more frequently (P less than 0.015) in patients with seronegative poly-arthritis combined with psoriasis (S- P+; n = 92) than in patients with seronegative polyarthritis alone (S- P-; n = 72). However, the prevalence of affection of these joints was too low to consider this feature a sensitive marker for psoriatic arthritis. Furthermore, neither asymmetrical joint involvement nor the absence of ulnar deviation of the fingers appeared to be characteristic of this disease. A positive correlation was found between the presence of nail psoriasis and limitation of function of the distal interphalangeal (DIP) joints. The DIP finger joints and the interphalangeal joints of the toes were affected more often in the S- P+ group than in patients with seropositive polyarthritis without psoriasis (S+ P-; n = 46), but arthritis of the other joints was observed more frequently in the latter group.