Overdose Risk Associated with Opioid Use upon Hospital Discharge in Veterans Health Administration Surgical Patients.

OBJECTIVE

To determine an association between opioid use upon hospital discharge (ongoing and newly started) in surgical patients and risks of opioid overdose and delirium for the first year.

DESIGN

Retrospective, cohort study.

SETTING

Population-level study of Veterans Health Administration patients.

SUBJECTS: All Veterans Health Administration patients (N = 64,391) who underwent surgery in 2011, discharged after one or more days, and without a diagnosis of opioid overdose or delirium from 90 days before admission through 30 days postdischarge (to account for additional opioid dosing in the context of chronic use).

METHODS

Patients' opioid use was categorized as 1) no opioids, 2) tramadol only, 3) short-acting only, 4) long-acting only, 5) short- and long-acting. We calculated unadjusted incidence rates and the incidence rate ratio (IRR) for opioid overdose and drug delirium for two time intervals: postdischarge days 0-30 and days 31-365. We then modeled outcomes of opioid overdose and delirium for postdischarge days 31-365 using a multivariable extended Cox regression model. Sensitivity analysis examined risk factors for overdose for postdischarge days 0-30.

RESULTS

Incidence of overdose was 11-fold greater from postdischarge days 0-30 than days 31-365: 26.3 events/person-year (N = 68) vs 2.4 events/person-year (N = 476; IRR = 10.80, 95% confidence interval [CI] = 8.37-13.92). Higher-intensity opioid use was associated with increasing risk of overdose for the year after surgery, with the highest risk for the short- and long-acting group (hazard ratio = 4.84, 95% CI = 3.28-7.14). Delirium (IRR = 10.66, 95% CI = 7.96-14.29) was also associated with higher opioid intensity.

CONCLUSIONS

Surgical patients should be treated with the lowest effective intensity of opioids and be monitored to prevent opioid-related adverse events.