Risk factors for opioid overdose among hospitalized patients

Hospitalized patients are at risk for opioid overdose. Little is known about the risk factors for these events.

Opioid overdose cases were identified by naloxone orders in computerized order entry system from a single institution. For each case, two controls were randomly selected. Data were collected on factors including age, gender, weight, opioid dose, route of administration, concomitant CNS depressants, renal function and comorbid conditions.

Between 2010 and 2013, we identified 44 cases of opioid overdose (OD), none of which were fatal, and matched these to 88 controls (no OD). Patients with a history of substance use disorder were excluded from the study. Factors associated with opioid overdose included age of 65 or older (40.9% OD vs 29.5% no OD, P = .026), being in an ICU (MICU/CICU 27.3% OD vs. 3.4% no OD, P < .001; SICU 18.1% OD vs 5.7% no OD, P = .031) and renal impairment (eGFR ≤60, 50.0% OD vs 28.4% no OD, P = .034). Total 24-hour opioid dose was lower in OD group, but the difference was not statistically significant (71.9 vs 107.2 mg morphine equivalent, P = .116). OD cases were more likely to have received concomitant CNS depressants, but the difference was statistically significant only for those who received 3 or more (15.9% OD vs 0% no OD, P = <.001). Heart disease was the only comorbidity significantly associated with an increased risk of opioid overdose (43.2% vs 20.5%, P = .025). Patient's BMI, duration of opioid use, route of administration and history of COPD and/or psychiatry were not associated with opioid overdoses.

Among hospitalized patients, risk factors of opioid overdose include age of 65 or greater, being in an ICU, renal impairment and concomitant administration of CNS depressant medications. These findings may help with the development and implementation of measures to prevent overdose.