The Association Between Patient Characteristics and Pain, Physical Function, and Quality of Life Among Patients with Hip Osteoarthritis: Explorative Study with Data from a Randomized Controlled Trial

Background: Hip Osteoarthritis (OA) is a degenerative joint disease associated with pain, reduced physical function, and impaired quality of life (QoL). Identifying patient characteristics associated with these outcomes may improve understanding of disease impact and support individually tailored treatment. Purpose: To explore associations between patient characteristics and key outcomes of pain, physical function, and QoL among individuals with hip OA. Secondarily, to investigate differences in pain, physical function, and QoL between patients recruited from hospitals and physiotherapy clinics in Denmark. Study design: Explorative cross-sectional study, with baseline data from a randomized controlled trial. Methods: Baseline data from The Hip Booster Trial was analyzed, including 159 adults with clinically diagnosed hip OA recruited from physiotherapy clinics and hospitals in Denmark. Associations between BMI, physical activity, age, sex, symptom duration, analgesic use (yes/no), muscle power (watts), educational level, and patient reported outcomes (HOOS pain, ADL, QoL) and the 30s-Chair Stand Test (CST) were evaluated using multiple linear regression. Change in the independent variable required to achieve a minimal important difference (MID) was calculated. Results: Of the eight characteristics investigated, two were associated with all key outcomes. Higher muscle power was associated with less pain (0.08 points, 95% CI 0.02; 0.13), better QoL (0.05 points, 95% CI -.01; 0.11), and better physical function; HOOS ADL (0.10 points, 95% CI 0.04; 0.16), 30s-CST (0.02 repetitions, 95% CI 0.01; 0.03). The use of analgesics was associated with worse HOOS pain (-10.99 points, 95% CI -15.66; -6.31), worse HOOS QoL (-7.89 points, 95% CI -13.30; -2.49), and poorer physical function measured by HOOS ADL (-8.25 points, 95% CI -13.63; -2.86), and 30s-CST (-.76 repetitions, 95% CI -1.84; 0.32). Conclusion: Greater muscle power was associated with better outcomes for HOOS Pain, QoL, ADL, and the 30s-CST, whereas use of analgesics was negatively associated with these outcomes.