Inpatient administration of opioids and risk for post-operative ileus in older adults

Objective: Post-operative ileus (POI) is a common and potentially serious complication after surgery. We assessed the incidence and identified predictors of POI in older surgical patients.Design: A retrospective observational study.Setting: University of California-San Francisco electronic medical record data.Participants: Opioid-naïve, noncancer patients, aged 65 and older, who underwent elective surgery in the period 2017-2019.Exposure: Administration of opioid analgesics per day of hospitalization in opioid naïve patients.Main outcomes measure: Incidence of POI and likelihood of developing POI.Results: In the study period, 3 percent of opioid naïve patients developed POI. Patients with POI used on average 197.1 oral morphine equivalents (OMEs) per day of hospitalization compared to 82.5 OME in patients without POI (p = 0.013). Yet, there were not statistically significant differences in post-operative pain scores between patients with and without POI. General surgery (p = 0.0031), length of surgery (p = 0.0031), and hospital length of stay (p < 0.0001) were significant predictors of the risk for developing POI. Adjusted inpatient administration of more than 90 OME per day of hospitalization was associated with a four times greater risk for developing POI (p = 0.016). Developing POI was associated with 6.5 (95 percent confidence interval: 5.2-7.8) additional days of hospitalization among patients who developed POI compared to patients who did not develop POI (p < 0.0001).Conclusions: Adjusted inpatient administration of more than 90 OME significantly increased the risk for developing POI in opioid-naïve older patients. Developing POI after surgery significantly increased the hospital length of stay. Optimizing inpatient administration of opioids may prevent opioid use-related POI and longer hospitalizations.