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

Abstract

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.