Patterns, circumstances and risk factors leading to non-fatal drug overdose in a cohort of homeless population

Abstract

Background It is known that most people who die from a drug overdose will have experienced some form of non-fatal overdose (NFOD) prior to the fatal event. Understanding the circumstances and risk factors of NFOD is key to reducing drug-related deaths, particularly in homeless populations where drug deaths dominate other causes of mortality. This study aimed to identify patterns, circumstances and risk factors leading to non-fatal overdose in people experiencing homelessness (PEH).Methods All recorded cases of NFOD from a population of PEH registered at a specialist primary care centre in England, UK, were identified using electronic patient-level medical records. Details of each overdose and patient characteristics were extracted. The heterogeneity between different variables with and without non-fatal overdoses were tested using Chi-square for parametric and Wilcoxon sum rank tests for non-parametric data. Multivariable logistic regressions were carried out to identify the risk factors of NFODs.Results From 1221 persons registered, 194 (16%) were identified as ever having had a NFOD with 428 overdoses between them. Of overdoses where implicated substances were recorded (264/428, 62%), half (n = 132) were polydrug related. Male sex was associated with a reduced risk of NFOD (OR: 0.52, 95% CI: 0.33–0.81), white ethnicity a greater risk compared to Black/African/Caribbean (0.52, 0.21–0.85) or Asian (0.42, 0.20–0.89) and age 36–45 associated with higher risks (3.86, 1.33–11.22). Use of tobacco (5.45, 1.41-21.00) and alcohol (2.19, 1.51–3.17) increased the risk, as did a record of illicit substance use (5.86, 3.58–9.58). Chronic physical and mental health conditions also increased the risk of NFOD including respiratory conditions (1.84, 1.20–2.81), blood borne viruses (2.19, 1.46–3.28), migraines (2.21, 1.06–4.62), anxiety (2.27, 1.59–3.26) and depression (1.79, 1.26–2.55). Main substances of overdose were paracetamol (25%), heroin (23%), benzodiazepines (14%), cocaine (13%), antipsychotics (11%), SSRI’s (11%) and synthetic cannabinoids (9%).Conclusions Male sex, white ethnicity, alcohol and substance misuse, and presence of chronic mental and physical comorbidities were associated with higher NFOD in PEH. Prevention programmes focusing on preventing drug related deaths can benefit by prioritising people with higher risks. Future work should explore the role of chronic physical conditions and their treatment on NFOD risk.