Biopsychosocial determinants of hand function and its trajectories over five years in patients with hand osteoarthritis

OBJECTIVES: This study aimed to investigate hand function trajectories over 5 years in primary hand osteoarthritis. Additionally, determinants of baseline and longitudinal hand function were assessed. METHODS: 538 patients with both baseline and 5-year study visits were analyzed. Annual data of the Australian Canadian OA hand index (AUSCAN) function subscale (range 0-36) from the HOSTAS (Hand OSTeoArthritis in Secondary care) study were used. Latent Class Growth Analysis (LCGA) identified hand function trajectories. Baseline and longitudinal associations with hand function were assessed using multivariable linear and multinomial logistic regression. RESULTS: 538 patients (86.1% women, mean age 61.0 years) with a mean [SD; range] AUSCAN function 15.6 [8.4; 0-36], higher scores indicate worse hand function) were included. Multivariable analysis showed that hand function was cross-sectionally associated with AUSCAN pain, grip strength, hand mobility, and the illness perception consequences. In 301 patients with 5-year follow-up data, four hand function trajectories emerged. The worst trajectories were defined by baseline function scores of 23.69 (CI95% 22.04, 25.61) with a slope of 0.36 (CI95% 0.03, 0.69) and 16.87 (CI95% 15.41, 18.34) with a slope of 0.38 (CI95% 0.01, 0.74) and deteriorated over 5 years (mean decrease of respectively 1.82 and 1.88). Deteriorating trajectories were associated with structural damage and the illness perception chronicity of disease. CONCLUSION: Hand function varies greatly in patients with hand OA. LCGA identified four longitudinal patient groups, of which two showed an unfavorable hand function course over 5 years. Hand function was characterized by disease characteristics, including structural damage and psychosocial determinants.