Similar Impact of Psoriatic Arthritis and Rheumatoid Arthritis on Objective and Subjective Parameters of Hand Function.

OBJECTIVE The objective of this study was to compare the impact of psoriatic disease (psoriatic arthritis [PsA] and psoriasis) and rheumatoid arthritis (RA) on objective and subjective parameters of hand function. METHODS Hand function was determined in this cross-sectional study by 1) vigorimetric grip strength, 2) the Moberg Picking-Up Test used for assessing fine-motor skills, and 3) self-reported hand function (Michigan Hand Questionnaire). Mixed-effects linear regression models were used to test the relation of hand function with disease group, age, and sex. RESULTS Two hundred ninety-nine subjects were tested, 101 with RA, 92 with PsA, and 106 nonarthritic controls (51 with psoriasis and 55 healthy controls [HCs]). Regression analysis showed that hand function was influenced by age, sex, disease group, and hand dominance (P < 0.001 for all). The impact of PsA and RA on hand function was comparable and generally more pronounced in women. Both PsA and RA led to significantly enhanced age-related loss of grip strength, fine-motor skills, and self-reported hand function in patients with PsA and RA compared with HCs. In addition, patients with psoriasis showed significant impairment of hand function compared with HCs. CONCLUSION RA and PsA have a comparable impact on the decline of strength, fine-motor skills, and self-reported function of the hand. Unexpectedly, patients with psoriasis also show impaired hand function that follows a similar pattern as observed in patients with PsA.