Alcohol and non-fatal drug overdoses

The purpose of this study was to explore to what extent alcohol is a factor in non-fatal overdoses on the basis of records of ambulance emergencies, and to what extent this varies across gender and age. Furthermore, we wanted to investigate whether alcohol intake, in relation to an overdose, is associated with the risk of recurrent overdoses, and if so, whether such an association varies across gender and age. To investigate the role of alcohol intake in non-fatal overdoses, analyses were conducted both at the event level and at the individual level. Bivariate associations were explored in table analyses and by comparisons of means. To determine whether alcohol intake was associated with experiencing recurrent overdoses, survival analyses were conducted applying Kaplan-Meier estimation and Cox regression models. Furthermore, a linear regression model was estimated to assess the impact of gender age and number of overdoses on the proportion of overdoses in which alcohol was involved. Between groups of clients who had overdosed once, several times or many times, we found that there was a U-shaped relationship. The proportion of overdoses with alcohol involved was highest among those who had overdosed once and those who had overdosed more than ten times. The probability for a recurrent overdose was higher among those who were reported with no alcohol intake in the first overdose. Being female and having alcohol involved in the first overdose registered during our observation period reduced the risk for a recurrent overdose. However, age seemed to be a gradient with respect to alcohol's association with recurrent overdoses. While alcohol was associated with a significantly lower risk for recurrence in the two youngest age groups, this is not the case in the oldest age group. A possible explanation might be that it is a change in the pattern of drug use as an effect of aging where infrequent heroin use in combination with frequent alcohol intake increases with increasing age. For this type of drug users the individual's risk of recurrent overdoses may be lower due to fewer events of heroin intake.