Do Comorbidities Play a Role in Hand Osteoarthritis Disease Burden? Data from the Hand Osteoarthritis in Secondary Care Cohort

Objective. Because the association and its clinical relevance between comorbidities and primary hand osteoarthritis (OA) disease burden is unclear, we studied this in patients with hand OA from our Hand OSTeoArthritis in Secondary care (HOSTAS) cohort. Methods. Cross-sectional data from the HOSTAS study were used, including consecutive patients with primary hand OA. Nineteen comorbidities were assessed: 18 self-reported (modified Charlson index and osteoporosis) and obesity (body mass index ≥ 30 kg/m 2 ). Mean differences were estimated between patients with versus without comorbidities, adjusted for age and sex: for general disease burden [health-related quality of life (HRQOL), Medical Outcomes Study Short Form-36 physical component scale (0–100)] and disease-specific burden [self-reported hand function (0–36), pain (0–20; Australian/Canadian Hand OA Index), and tender joint count (TJC, 0–30)]. Differences above a minimal clinically important improvement/difference were considered clinically relevant. Results. The study included 538 patients (mean age 61 yrs, 86% women, 88% fulfilled American College of Rheumatology classification criteria). Mean (SD) HRQOL, function, pain, and TJC were 44.7 (8), 15.6 (9), 9.3 (4), and 4.8 (5), respectively. Any comorbidity was present in 54% (287/531) of patients and this was unfavorable [adjusted mean difference presence/absence any comorbidity (95% CI): HRQOL −4.4 (−5.8 to −3.0), function 1.9 (0.4–3.3), pain 1.4 (0.6–2.1), TJC 1.3 (0.4–2.2)]. Number of comorbidities and both musculoskeletal (e.g., connective tissue disease) and nonmusculoskeletal comorbidities (e.g., pulmonary and cardiovascular disease) were associated with disease burden. Associations with HRQOL and function were clinically relevant. Conclusion. Comorbidities showed clinically relevant associations with disease burden. Therefore, the role of comorbidities in hand OA should be considered when interpreting disease outcomes and in patient management.