Opioid use among Danish patients with severe knee osteoarthritis: a drug utilization study.

Abstract

Knee osteoarthritis (OA) is one of the most common musculoskeletal diseases. Opioids have been increasingly used in the treatment of severe knee OA-related pain, particularly in the USA. Less is known about the patterns of use of opioids among Danish patients with severe knee OA. We investigated opioid use among Danish patients with severe knee OA in the 5years preceding knee replacement surgery (KR). We identified adults who had undergone KR from January 1st, 2005, to December 31st, 2018, using the Danish National Patient Register. These patients were considered to have severe knee OA in the 5-year period leading up to KR. Individual-level data on prescribed opioids were retrieved from the Danish National Prescription Registry. We identified 77,168 severe knee OA patients (mean age 66years). The prevalence of opioid users increased from 21% 5years before KR to 40% 1year before. Total use of opioids increased each year and doubled from 3254mg oral morphine equivalents (OMEQ)/1000 individuals/day 5years before to 6396mg OMEQ/1000 individuals/day the year before KR corresponding to an increase of 3141mg OMEQ (95% confidence interval 3010 to 3273). Tramadol was the most frequently used opioid. About 10% of the population accounted for 90% of the total opioid use. Among patients with severe knee OA, the prevalence and total use of opioids doubled during the 5years before KR. In addition, 10% of the study population was responsible for 90% of the opioids used.