Increased Analgesic Prescribing Observed in Patients With Knee Osteoarthritis

An overall increase in analgesic prescribing was observed in patients with knee osteoarthritis (OA), according to study findings published in Pain Practice. 

Investigators from the University of Nottingham in the UK performed a retrospective, cross-sectional study using data sourced from the Clinical Practice Research Datalink-Gold database. Patients with a documented knee OA diagnosis between 2000 and 2014 at primary care sites in the UK were evaluated to identify trends in analgesic prescribing practices.

The study population included 117,637 patients with a mean (SD) age of 66.3 (12.7) years, of which 69,053 (58.7%) were women.

During the study period, 79.1% received prescriptions for opioids; 72.0% received prescriptions for non-steroidal anti-inflammatory drugs (NSAIDs); 70.1%, for paracetamol; 45.5%, for antidepressants, and 13.4%, for anti-epileptic drugs (AEDs).

Overall, prescriptions for AEDs increased by 450%, for antidepressants by 152.8%, for opioids by 69.5%, and for paracetamol by 52.2% from 2000 to 2014. On the other hand, prescriptions for NSAIDs decreased by 57.7% in that same period.

Paracetamol had the highest mean annual defined daily doses (DDDs), ranging between 0.79 and 1.40 per 1000 patients. Over time, DDDs of antidepressants increased overall, but more so for selective serotonin reuptake inhibitors (from 0.09 to 0.32 DDD/1000 patients) than for other classes of antidepressants (from 0.02 to 0.07 DDD/1000 patients). Similarly, the DDD for newer classes of AEDs, such as gabapentinoids, increased over time.

Most patients prescribed opioids received an oral morphine equivalent dose (OMEQ) of up to 50 mg/day. But the proportion of patients who received OMEQs of 51 to 100 mg increased by 361% and 101 to 200 mg by 108% between 2000 and 2014.

The mean annual days’ supply per patient was also observed to increase by 29.7% for opioids, 29.0% for paracetamol, 16.2% for NSAIDs, and 11.8% for antidepressants, whereas that number decreased by 19.4% for

Limitations of the study included that the data were sourced from primary care providers, so prescription adherence and dispensation were assumed. In addition, NSAID and paracetamol use may have been underestimated as these analgesics are widely accessed over the counter.

“The increased prescribing for most of the studied drug classes, particularly opioids and AEDs, warrants further investigation into drug exposure and outcomes for individual patients to [optimize] safety of analgesic use in this patient population,” the study authors concluded.