Detection of hidden populations using illicit substances.

BACKGROUND

The prevalence of hidden populations using illicit substances may lead to underestimation of the health and social impacts. This study aimed to precisely estimate the prevalence and characteristics of hidden populations using illicit drugs.

METHODS

We linked national databases in Taiwan, including drug-related autopsy data and police arrest data. This study included individuals who died, underwent autopsy and showed positive drug results during autopsy, covering heroin, methamphetamine, ketamine, ecstasy and new psychoactive substances (NPS), from 2013 to 2019. We subsequently identified individuals who were arrested for illicit drug use (registered individuals) and individuals without arrest records (unregistered individuals) from 2010 to 2019.

RESULTS

A total of 1653 individuals in the autopsy database met the initial inclusion criteria. The ratio of unregistered individuals to registered individuals was 0.7 for heroin, 2.2 for methamphetamine, 14.8 for ecstasy, 4.9 for ketamine and 174.0 for NPS. Unregistered individuals were younger, more likely to be female, employed and had higher alcohol levels in their blood samples. These results remained consistent across the sensitivity analyses, encompassing both registered individuals who did not undergo autopsy and those who remained alive. Approximately 79% of the polydrug use detected at autopsy was among unregistered individuals, and 10% of unregistered individuals had other substance use records that differed from those detected at death.

CONCLUSIONS

Our approach, which incorporates both registered and unregistered individuals who use substances, shows good potential for evaluating hidden populations. Clinicians should be more attentive to potential polydrug use, even when cross-sectional urine drug tests indicate single substance use.