A new study has shown that each refill and week of opioid prescription is associated with a large increase in opioid misuse
The study, published in the BMJ, aimed to quantify the effects of varying opioid prescribing patterns after surgery on dependence, overdose or abuse in opioid-naïve patients.
The researchers took information on surgical patients with medical and pharmacy insurance from a de-identified administrative database at the commercial managed health care company Aetna.
The database included 37,651,619 members with health and pharmacy insurance coverage between 2008 and early 2016; the researchers identified 1,015,116 opioid-naïve patients who underwent surgery. They were then followed for a median of 2.67 years to examine their opioid refill and use patterns, and any misuse.
After the index surgery, 568,612 members (56%) filled a prescription for a postoperative opioid. Ninety per cent of prescriptions were filled within three days of discharge.
In the subsequent follow-up period, misuse was identified in 5,906 members (0.6%, 183 cases per 100,000 person years), with 1857 occurring within one year after surgery (0.2%).
“The number of post-discharge prescriptions best predicted eventual misuse,” the authors wrote.
“Overall rates of misuse were low, but rates grew rapidly with increasing opioid use.”
The rate of misuse more than doubled among those with one refill (86,654 (15.2%); 293 cases per 100,000 person years) versus those with no refills (434,273 (76.2%); 145 cases per 100,000 person years).
In total, each additional refill increased the rate of misuse by 70.7% (95% confidence interval 54.6% to 88.4%) before adjustment and increased the hazard of misuse by 44.0% (40.8% to 47.2%, P<0.001) after adjusting for covariates.
“The relation between number of refills and misuse was further supported by evaluation of the number of days of opioid use post-discharge,” the authors wrote.
Each additional week of opioid use was associated with an average increase in the rate of misuse of 34.2% (26.4% to 42.6%, P<0.001). Adjusting for covariates, each additional week of opioid use was associated with a 19.9% increase in hazard (95% confidence interval 18.5% to 21.4%, P<0.001).
The authors highlight that overprescribing of opioids is thought to be a major contributor in the skyrocketing rates of opioid overdose in the US, with prescription drugs implicated in most cases and with two-thirds of opioid misuse attributable to opioids obtained via a single physician.
“This study quantifies the strong relation between number and duration of refills of prescribed opioid drugs and subsequent opioid misuse in the surgical population,” the authors wrote.
“A single refill increased the potential of misuse by more than 40%, and the duration of use appeared to be the most prominent predictor of misuse.
“Surgeons and non-surgeons are changing the characteristics of their opioid prescriptions, but rates of misuse continue to increase.
“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.”