Background: Opioid overdoses are increasing in the Netherlands, and there may be other harms associated with prescription opioid use. We investigated the relationship between prescription opioid... Show moreBackground: Opioid overdoses are increasing in the Netherlands, and there may be other harms associated with prescription opioid use. We investigated the relationship between prescription opioid use and unplanned ICU admission and death. Methods: This is an analysis of linked government registries of the adult Dutch population (age >= 18 years) alive on January 1, 2018. The co-primary outcomes were ICU admission and death up to 1 year. Crude event rates and eventspecific adjusted hazard rates (aHRs) with 95% confidence intervals (CIs) were calculated using multivariable analysis for people with and without exposure to an opioid prescription. Results: We included 13 813 173 individuals, of whom 32 831 were admitted to the ICU and 152 259 died during the 1 year follow-up. Rates of ICU admission and death amongst people who reimbursed an opioid prescription were 5.87 and 62.2 per 1000 person-years, and rates of ICU admission and death in those without a prescription were 2.03 and 6.34, respectively. Exposed individuals had a higher rate of both ICU admission (aHR 2.53; 95% CI: 2.45e2.60) and death (aHR 7.11; 95% CI: 7.02e7.19) compared with unexposed individuals. Both outcomes were more frequent amongst prescription opioid users across a range of subgroups. Conclusions: The rate of ICU admission and death was higher amongst prescription opioid users than non-users in the full cohort and in subgroups. These findings represent an important public health concern. Show less