Background:

The basic sources of information on drug use are epidemiological surveys, although they have some limitations: their results may be conditioned by the lack of veracity of the responses and the sampling method makes it difficult to detect low-prevalence behaviours in target populations. This study aimed to establish the epidemiological pattern of drug use in the population undergoing drug testing in hair, in the framework of judicial investigations, in order to provide an additional approach to the knowledge of high-risk drug use.

Methods:

A cross-sectional study on drug use was conducted on the population subjected to drug testing in hair (N=5,292) in the forensic context. Prevalence of cannabis, cocaine, heroin, ketamine, amphetamine (AP), methamphetamine (MA), 3,4-methylenedioxy-methamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA) and methadone uses were obtained. Association between drug use and demographics, and trends of prevalence over the period were analysed using the Pearson Chi-square test. Frequency distribution of drug concentrations in hair was obtained and it was assessed in relation to gender and age using the non-parametric Mann-Whitney U and Kruskal-Wallis H methods.

Results:

During the period 2013-2015, prevalence of cocaine use was particularly high (49%), rating second among the population studied, after cannabis use (54%). Proportions of heroin, methadone, MDMA and amphetamine use ranged from 10% to 18%. There was a significant increase in prevalence of MDMA, heroin and amphetamine use during the period 2013-2015, as well as a significant decrease in methadone use. The rates of cannabis, cocaine and MDMA use were higher in men, whereas methadone use was higher among women.

Conclusions:

Cannabis and cocaine are the most frequently abused drugs among the population undergoing drug testing in hair in the framework of judicial investigations over the three-year period, although the proportions of heroin, MDMA and amphetamine users show an increasing trend. Drug use patterns vary according to age and sex, with a decrease in cannabis and MDMA use and an increase in heroin and methadone use as age increased; cannabis, cocaine and MDMA use are more prevalent among men and methadone use among women.

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