Postoperative opioid misuse in patients with opioid use disorders maintained on opioid agonist treatment

Background: Patients recovering from opioid use disorders (OUD) may be prone to relapse and opioid misuse in the postoperative period due to re-exposure to prescription opioids for pain control. This retrospective study analyzed the incidence of confirmed opioid misuse in the postoperative period in patients with OUDs enrolled in an opioid agonist treatment (OAT) program. Methods: The study population was US veterans with a diagnosis of OUD who enrolled in the OAT program at VA Maryland Health Care System (Baltimore, Maryland, USA) between 1/1/2000 and 12/31/2016. The patients were excluded if they were enrolled in OAT for less than a year, or if they had surgery within the first 180 days after OAT admission. The surgical group consisted of veterans who had surgery or an invasive procedure during their enrollment in the OAT program. The control (reference) group consisted of enrolled veterans who did not have any invasive procedure. The primary outcome was the first opioid misuse within 365 days after surgery date in the surgical group or a randomly assigned sham surgery date in controls. Opioid misuse was defined as either inappropriate use of opioids detected via urinalysis or admission with a diagnosis of an opioid overdose. Results: From a total of 1352 patients enrolled in the OAT program, 413 were excluded because they were enrolled for less than a year, and 26 were excluded because they had surgery within the first 180 days after admission to the OAT program. Of the 923 eligible patients, 87 had surgery while enrolled and 836 did not. Using propensity scores, all 87 of the surgical cases were matched to 249 of the control cases. In the matched groups, surgery was positively associated with postoperative opioid misuse (odds ratio (OR) of 1.91, 95% CI 1.05-3.48, p = 0.034) in logistic regression. Conclusion: Among patients with a history of opioid use disorders, the postoperative period was associated with an increased risk of opioid misuse. Moreover, opioid misuse among patients in an opioid agonist treatment program may well be considered a surgical hazard.