Hand Function Impairments Are More Pronounced in Female RA and PsA Patients and Also Found in Patients without Concurrent Hand Inflammation.

Abstract

Hand function is considered being critical in rheumatoid (RA) and psoriatic arthritis (PsA) patients; however, comprehensive assessment of hand function is rarely done in patients with inflammatory arthritis. In this cross-sectional study, RA and PsA patients and healthy controls (HC) were assessed for hand function using isometric grip strength (dynamometer), dynamic grip strength (vigorimeter), and fine-motor skills (Moberg Picking-Up Test). Between-group differences and the associations with disease activity (Disease Activity Score 28 (DAS28), RA, Disease Activity in Psoriasis Arthritis (DAPSA), PsA) were analyzed using linear mixed-effects models, with age as a covariate and participants' ID as a random intercept term. All analyses were stratified by sex and additionally employed for a subgroup without concurrent hand inflammation (no tender and swollen joints, no ultrasound signs of inflammation). A total of 225 participants were included (76 PsA, 73 RA, and 76 HC). RA and PsA patients showed a similar reduction in isometric and dynamic grip strength and fine-motor skills compared with HC. Impairment of hand function was particularly pronounced in female RA and PsA patients, whereas grip strength was better maintained in males. A one-unit higher DAS28 or DAPSA was associated with lower dynamic grip strength for all RA and PsA patients, and one-unit higher DAPSA was additionally associated with lower fine-motor skills in female PsA patients. Female RA and PsA patients showed impairment in all measures of hand function even without concurrent hand inflammation, whereas among males, only PsA patients showed fine-motor skill impairment. Hand function is impaired to a similar extent in RA and PsA patients, more pronounced in female patients, and also found in the absence of concurrent hand inflammation.