To explore socio-economic inequalities in fatal overdose cases related to non-prescribed opioids’ and cocaine use.

Overdose cases recorded in Luxembourg between 1994 and 2011 were individually matched with four controls, in a nested case-control study design, according to sex, year of birth, drug administration route and duration of drug use. 272 cases vs. 1,056 controls were analyzed. The study sample was stratified according to a Social Inequality Accumulation Score (SIAS), based on educational attainment, employment, income, financial situation and professional status of father or legal guardian of subjects. Least squares linear regression analysis on overdose mortality rates and ridit scores were applied to determine the Relative Index of Inequality (RII).

A negative linear relationship between the overdose mortality rate and the relative socioeconomic position was observed. We found a difference in mortality of 29.22 overdose deaths per 100 drug users between the lowest socioeconomic class compared to the most advantaged class. In terms of Relative Inequality Index, the overdose mortality rate of opioid and cocaine users with lowest socioeconomic profiles was 9.58 times as high as that of their peers from the highest socioeconomic class (95% CI; 6.49 – 13.26).

Our results suggest the existence of a social gradient in opioid and cocaine related overdose fatalities. Medical services, emergency and psychiatric wards should take due account of the socio-economic situation of substance abusing patients and refer those at increased risk to socially supportive offers, thus contributing to reduce drug-related mortality.