Opioid Overdose Risk Following Hospital Discharge Among Individuals Prescribed Long-Term Opioid Therapy: a Risk Interval Analysis

Abstract

Background: Individuals prescribed long-term opioid therapy (LTOT) have increased risk of readmission and death after hospital discharge. The risk of opioid overdose during the immediate post-discharge time period is unknown.

Objective: To examine the association between time since hospital discharge and opioid overdose among individuals prescribed LTOT.

Design: Self-controlled risk interval analysis.

Participants: Adults prescribed LTOT with at least one hospital discharge at a safety-net health system and a non-profit healthcare organization in Colorado.

Main measures: We identified individuals prescribed LTOT who were discharged from January 2006 through June 2019. The outcome was a composite of fatal and non-fatal opioid overdoses during a 90-day post-discharge observation period, identified using electronic health record (EHR) and vital statistics data. Risk intervals included days 0-6 after index and subsequent hospital discharges. Control intervals ranged from days 7 to 89 after index discharge and included all other time during the observation period that did not fall within a risk interval or time readmitted during a subsequent hospitalization, which was excluded. Poisson regression was used to estimate incidence rate ratios (IRR) and 95% confidence intervals (CI) for overdose events during risk in comparison to control intervals.

Key results: We identified 7695 adults (63.3% over 55 years, 59.4% female, 20.3% Hispanic) who experienced 9499 total discharges during the study period. Twenty-one overdoses occurred during their observation periods (1174 per 100,000 person-years [9 in risk, 12 in control]). Overdose risk was significantly higher during the risk interval in comparison to the control interval (IRR 6.92; 95% CI 2.92-16.43).

Conclusion: During the first 7 days after hospital discharge, individuals prescribed LTOT appear to be at elevated risk for opioid overdose. Clarifying mechanisms of overdose risk may help inform in-hospital and post-discharge prevention strategies.

Keywords: LTOT; discharge; hospitalization; opioid; overdose.

Figure 1

Risk interval design schematic (not to scale): 90-day observation period by different hypothetical patient scenarios. Patient A: One overdose event in the 0–6-day risk interval after hospital discharge. No other hospitalizations or overdose events during the observation period. Patient B: Two overdose events in the control interval. Patient C: Subsequent hospitalization discharge exposure during the observation period with an overdose event in the 0–6-day risk interval after subsequent discharge. *End of the observation period: Follow-up censored at health plan disenrollment, death, disqualifying hospitalization (i.e., hospitalization >32 days or with discharge disposition to a structured living environment) or the end of the observation period, whichever occurred first. ^†Time hospitalized: Subsequent hospitalization during observation period; time spent hospitalized excluded from analysis.

Figure 2

Hospital discharge exposures. *Index hospital discharge: Corresponding hospitalization where patient (1) prescribed LTOT in the 90-day period preceding admission, (2) admitted for ≤32 days, (3) alive at the time of discharge, and (4) discharged to an independent living environment. ^†Subsequent hospital discharges: Hospital discharges that occurred within 0–89 days after the index hospital discharge and prior to the censoring date.