Opioid Use After ICU Admission Among Elderly Chronic Opioid Users in Ontario: A Population-Based Cohort Study

Objectives: Critical illness is often associated with painful procedures and prolonged opioid infusions, raising the concern that chronic opioid users may be exposed to escalating doses that are continued after hospital discharge. We sought to assess patterns of opioid use after intensive care among elderly patients identified as chronic opioid users prior to hospitalization. Design: Population-based cohort study. Setting: All adult ICUs in the province of Ontario, Canada. Participants: Elderly patients (> 65 yr) admitted to ICUs between April 2002 and March 2015 who also survived to day 180 after hospital discharge, identified as chronic opioid users prior to hospitalization. Exposure: Chronic opioid use in the year before hospital admission, as well as a filled opioid prescription with a duration covering the day of hospital admission. Measurements and Main Results: The primary outcome was the proportion of patients who filled an opioid prescription with a duration covering day 180 after hospital discharge; secondary outcome was the difference in morphine equivalent daily dosage at day 180 after discharge compared with the amount prescribed prior to hospital admission. Of 496,985 elderly admissions to ICUs, 19,584 (3.9%) were chronic opioid users before hospitalization who also survived to day 180 after hospital discharge. The median daily dose of opioid prescriptions filled before hospital admission was 32.1mg morphine equivalent (interquartile range, 17.5-75.0mg morphine equivalent). Among these survivors, 63.3% had at least one opioid prescription filled with a duration covering day 180; 22.0% had filled prescriptions for a higher daily morphine equivalent dose compared with prehospitalization, 19.8% were unchanged, 21.5% had a lower dose, and 36.7% had no prescription filled. The majority of reduction was in prescriptions for codeine and oxycodone. Conclusions: Among chronic opioid users, hospitalization with critical illness was not associated with substantial increases in opioids prescribed in the 6 months following hospitalization.