Patients with osteoarthritis who start opioid treatment at higher doses tend to have higher treatment-failure rates, according to an industry-sponsored study

The findings were presented in a poster on September 13 at the International Association for the Study of Pain (IASP) World Congress on Pain in Boston. "The results from this study suggest that (patients) initiated on higher intensity opioid regimens generally have a higher likelihood of clinically undesirable outcomes and there is a need for new treatment options for this subgroup" of osteoarthritis patients, Dr. Nathaniel Katz of Analgesic Solutions in Wayland, Massachusetts, and colleagues write in their abstract.

Dr. Katz and his colleagues analyzed a Medicare and employer-sponsored insurance-claims database for 2011-2016 for patients with two or more hip/knee osteoarthritis-diagnosis claims who filled an opioid prescription (index event) within 30 days of being diagnosed with osteoarthritis. Anyone who had surgery before filling the prescription was excluded from the study.

The researchers classified the index opioid regimen intensity by how frequently the drug was used: intermittent (four or fewer days per week); daily; or more than four days per week. They categorized the average daily dose as low at under 50 morphine mg equivalents (MME) per day and high at 50 or more MME per day.

Clinical outcomes

The authors considered index opioid-regimen failure to be increased opioid-regimen intensity, the addition of a non-opioid medication to manage pain or clinical outcomes such as joint surgery or opioid-abuse-related events.

They evaluated the records of more than 271,000 female and male patients, who averaged almost 60 years of age. Overall, 61.5% were treated for knee problems, 11.1% for hip problems and 27.4% for both.

By the time they had been taking the drug for one year, 34.9% of patients failed their index opioid regimen, due mainly to increased regimen intensity (16.1%), joint surgery (14.0%), addition of non-opioid pain medication (11.4%) and events related to opioid abuse (1.9%). Some patients had multiple causes.

The failure rate generally increased with higher index-regimen intensity: for intermittent low-dose short-acting opioids (SAO), it was 31.4%; for intermittent high-dose SAO, 27.8%; for daily low-dose SAO, 39.1%; for daily high-dose SAO, 55.4%; for daily long-acting opioids (LAO), 58.4%; and for daily LAO+SAO, 62.7%.

Intermittent groups were similar relative to daily low-dose SAO, but daily high-dose SAO, LAO, and LAO+SAO treatments were more likely to fail by one year (P <0.0001). And the median time to index-regimen failure was shorter at higher intensities (one year or less for daily high-dose SAO, LAO, and LAO+SAO).

The researchers note that study limitations include the inability to link pain-medication prescribing with OA, and the lack of statistical control for unobserved patient traits. They recommend future studies to evaluate the relationships between baseline disease features and choice of the opioid treatment regimen.