A study that analyzed insurance and prescription claims data identified the number of opioid refills and duration of use as stronger predictors of misuse by patients after surgery than opioid dose. The results offer insight into how opioid prescribing practices influence misuse-defined in the study as abuse, dependence, or overdose.

The study looked at Aetna insurance claims for roughly 1 million patients who had surgery between 2008 and early 2016 and were considered "opioid naive," meaning they had used an opioid for seven days or less during the 60 days before surgery. Of these patients, 56% filled a prescription for an opioid after surgery, most within three days of discharge. Over a median follow-up of nearly three years, close to 6,000 of these patients met the study's criteria for "opioid misuse," determined by diagnostic codes for opioid dependence, abuse, and/or overdose in their medical records. Almost 1,900 patients in this group were identified within the first postoperative year.

The strongest predictor of misuse was the duration of opioid use. After adjusting for possible confounding factors, the risk of misuse increased by 44% with each refill and by 20% for each week patients took opioids, both statistically significant associations. Even with one refill, the rate of misuse was more than twofold higher than with no refills (293 cases versus 145 cases per 100,000 person-years). Opioid dose, however, was a weaker predictor and "became important only with extended use," and even high doses "were associated with only mild increases in risk when duration was short," the researchers wrote. Although the mean opioid dose prescribed appeared to drop during the study period, the mean duration of opioid use was fairly stable and the association between duration and misuse persisted.

There appear to be "conflicting forces at play" among health care professionals, the authors observed. "Clinicians are trapped between guidelines that recommend shorter duration and lower dosing of opioid drugs and a subset of patients who request or require opioids beyond the initial prescription." They cited studies that "imply that optimal postoperative prescribing, which maximizes analgesia and minimizes the risk of misuse, may be achieved with moderate-to-high opioid dosages at shorter durations, a combination that merits further investigation in population-based and clinical studies."-Elizabeth Mechcatie, MA, BSN

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