Potential environmental triggers are streptococcal infection and physical trauma.
Females develop psoriatic arthritis slightly more commonly than males.
Psoriasis frequently first appears in childhood and psoriatic arthritis typically in young or middle adulthood, though there are many exceptions. In general, there is little relation between joint and skin severity. In fact, psoriatic skin lesions may be found only after careful scrutiny of scalp, umbilicus, or gluteal regions, and nail pitting or other changes may be the only clues supporting a diagnosis of psoriatic arthritis. The finding of involved distal interphalangeal joints and sausage-shaped toes or fingers are highly suggestive signs. Symmetrical polyarthritis may resemble rheumatoid arthritis, though the rheumatoid factor test should be negative.