Determination and characterization of patient subgroups based on pain trajectories in hand osteoarthritis

Objectives To investigate pain, pain trajectories and their determinants in hand osteoarthritis (OA). Methods Data from the HOSTAS (Hand OSTeoArthritis in Secondary care) consisting of consecutive hand OA patients were used. Australian Canadian Osteoarthritis Hand Index (AUSCAN) pain was measured yearly for four years. Patients with complete AUSCAN at >= 2 time points were eligible for longitudinal analysis. Associations between variables of interest and baseline AUSCAN pain were investigated with linear regression. Development of pain over time was modelled using latent class growth analysis (LCGA). Associations of LCGA classes with variables of interest were analysed using multinomial logistic regression adjusted for baseline pain. Results A total of 484/538 patients [mean (s.d.) age 60.8 (8.5) years, 86% women, mean (s.d.) AUSCAN pain 9.3 (4.3)] were eligible for longitudinal analysis. Sex, marital and working status, education, disease duration and severity, anxiety and depression scores, lower health-related quality of life (HR-QoL), specific illness perceptions and coping styles were associated with baseline pain. LCGA yielded three classes, characterized by average pain levels at baseline; average pain remained stable over time within classes. Classes with more pain were positively associated with BMI, tender joint count, symptom duration, hand function scores and depression scores, negatively with physical HR-QoL, and education level. Conclusion Baseline pain was associated with patient and disease characteristics, and psychosocial factors. LCGA showed three pain trajectories in hand OA patients, with different baseline pain levels and stable pain over time. Classes were distinguished by BMI, education level, disease severity, depression and HR-QoL.