Objective: Non-opioid analgesics (NOAs) are widely used to palliate osteoarthritis (OA) pain, however, their role in health-related quality of life (HRQoL) in OA has not been well studied. Here, we assess the relationship of pain, physical function, and HRQoL to NOA use in symptomatic knee OA.
Methods: NOA dose, pain, physical function, and HRQoL were evaluated longitudinally over 1 year in medial knee OA. Doses provided by subjects' weekly medication diaries were normalized to equi-analgesic ibuprofen-equivalents (IEs). Descriptive analyses at baseline, 1.5, and 12 months, and non-parametric comparisons of NOA with pain, physical function, and HRQoL at 1.5 months and over 12 months were performed.
Results: Seventy-one subjects (19 males and 52 females; mean 57+/-10.5 years) used an overall median of 300 mg/week of IE. Twenty-five subjects reported no analgesic use during the study; of the 46 subjects that reported NOA use, the median intake was 1325 mg/week IE. Whereas age, Physical Functioning (PF) and HRQoL were predictive of NOA dose both at 1.5 months and during the entire study, pain level was not. The median NOA dose declined over 12 months (P=0.02), however, the change was not associated with changes in PF, HRQoL or pain.
Conclusion: Greater age and worse physical function and HRQoL, but not pain severity, are predictive of NOA use in symptomatic knee OA. Longitudinally, NOA use does not change as a function of pain. These data suggest that pain is not the primary determinant of NOA use over time among OA patients.