Association between illicit drug overdose and encephalopathy in British Columbia, Canada: A cross-sectional analysis

Abstract Background In the context of the drug poisoning (overdose) crisis in British Columbia (BC), Canada, measuring the co-occurrence of encephalopathy and overdose is challenging due to lack of standardized screening. We aimed to estimate the prevalence of encephalopathy among people who experienced a drug poisoning event and examine the association between drug poisoning and encephalopathy. Methods Using a 20% random sample of BC residents from administrative health data, we conducted a cross-sectional analysis. Drug poisoning events were identified using the Provincial Overdose Cohort definition and encephalopathy was identified using ICD codes from hospitalization, emergency department, and primary care records between January 1st 2015 and December 31st 2019. Unadjusted and adjusted log-binomial regression models were employed to estimate the risk of encephalopathy among people who had a drug poisoning event compared to people who did not experience a drug poisoning event. Results Among people with encephalopathy, 14.6% (n = 54) had one or more drug poisoning events between 2015 and 2019. After adjusting for sex, age, and mental illness, people who experienced a drug poisoning were 15.3 times (95% CI = 11.3, 20.7) more likely to have encephalopathy compared to people who did not experience a drug poisoning event. People who were 40 years and older, male, and had a mental illness were at increased risk of encephalopathy. Conclusions There is a need for collaboration between health care providers, experts, and key stakeholders to develop a standardized approach to define, screen, and detect neurocognitive injury related to illicit drug poisoning.