Prescription patterns and predictors of unmet pain relief in patients with difficult-to-treat osteoarthritis in the Nordics: analyses from the BISCUITS study

Objectives: Osteoarthritis (OA) is one of the leading causes of disability worldwide. Pain is the most important symptom in OA, driving medical care, disability, reduced functionality, and decreased quality of life. The objective of this study was to describe prescription patterns of difficult-to-treat OA and explore possible predictors of unmet pain relief in Nordic patients. Methods: This observational cohort study included patients with a confirmed diagnosis of OA (index date) in specialty care in Sweden, Norway, Finland and Denmark between 1 January 2011 and 31 December 2012 who were followed for up to 5 years. Four subgroups were pre-defined to characterize difficult-to-treat OA: (1) ≥2 chronic comorbidities in the 3-year pre-index period; (2) top 10% of healthcare resource users, 1-year post-index; (3) ≥3 types of prescription pain medications during pre-index period to first year post-index, with ≥30 days between types; (4) having a contraindication to a nonsteroidal anti-inflammatory drug (NSAID). Patient characteristics, prescription patterns and predictors of unmet pain relief (defined as persistent opioid use, using several types of opioids or long-term NSAID use) were analyzed. Results: We identified 288,174 OA patients and the average age was 63.5 years at time of diagnosis and 58% of them were female. After 5 years, 35-50% of the patients defined as 'difficult-to-treat' had ≥1 prescription of opioids, compared to 20-25% of all OA patients (p-value <0.05). Comorbidities and disability pension were strong predictors of unmet pain relief (p-value <0.001). Conclusions: This study shows a substantial use of pain medications (NSAID and opioids) in difficult-to-treat OA patients. These findings suggest that pain may be inadequately managed in a considerable number of patients with OA, particularly those with contraindications to an NSAID. A high comorbid and socioeconomic burden are relevant risk factors among patients who continue to use opioids for a long period of time.