Association of past-year mental and physical health conditions with intentional or unintentional drug overdoses

Abstract

Introduction

Recent studies have explored the role of suicidal behavior in drug overdoses; however, differentiating intentional versus unintentional overdoses using large-scale, real-world electronic health records (EHRs) remains under-investigated. This study compared individuals with intentional or unintentional drug overdoses based on (1) demographic characteristics, (2) past-year diagnoses of mental and physical health conditions, and (3) the number and types of substances involved.

Methods

This retrospective cohort analysis used EHRs derived from five health systems across New York City. The study identified patients with an incident overdose encounter between 2011 and 2019 based on ICD-9 and ICD-10 codes, then stratified them as ‘intentional’ or ‘unintentional’ according to the intent specified by the ICD code. ICD codes also extracted past-year substance use disorders (SUDs), suicidal thoughts and behaviors (STBs), psychiatric disorders, and chronic conditions. Multivariable logistic regression models adjusted for age, sex, and race/ethnicity evaluated clinical predictors of an intentional overdose, and odds ratios (ORs) and 95 % confidence intervals (CIs) estimated effect sizes.

Results

The study identified 9622 patients, including 1737 (18.1 %) with an intentional overdose and 7885 (81.9 %) with an unintentional overdose. Intentional overdose patients (38.8 ± 19.8 years) were younger than unintentional overdose patients (53.3 ± 20.1 years). Women comprised the majority of intentional (67.6 %) and unintentional (52.4 %) overdose patients. An intentional overdose was more likely than an unintentional overdose in patients with past-year alcohol use disorder (OR: 1.94 [95 % CI: 1.54–2.44]), STBs (3.63 [2.90–4.54]), and psychiatric disorders (2.92 [2.51–3.39]), and less likely in those with past-year chronic conditions (0.50 [0.43–0.58]) (p < 0.001). Finally, intentional compared with unintentional overdoses were commonly observed during emergency department encounters (2.10 [1.87–2.35]) and involved multiple substances (19.8 %) such as non-opioid pain relievers (8.63 [7.30–10.21]), sedative-hypnotics (2.49 [2.04–3.04]), and benzodiazepines (3.42 [2.77–4.21]), whereas most unintentional overdoses involved a single substance (92.9 %) (p < 0.001).

Conclusions

Younger patients, often with mental health and SUD problems, have a relatively higher risk of intentional overdose, while older patients with chronic health conditions are more prone to unintentional overdose. Understanding the distinct mechanisms driving overdose intent is vital for tailoring interventions, given the greater risk of suicide death following a nonfatal intentional overdose.