Detection of hidden populations using illicit substances.
Shyh-Yuh Wei, Brian Meng-Hsun Li, Hsuan-Yun Hu, Daniel Hsiang-Te Tsai, Swu-Jane Lin, Szu-Yu Lin, Chien-Chou Su, Chih-Hsin Pan, Edward Chia-Cheng Lai
Journal of epidemiology and community health April 23, 2025 DOI: 10.1136/jech-2025-223903 via PubMed
Summary
AI-generated from the abstractHidden populations of people who use illicit drugs—those without arrest records—are much larger than official records suggest. In Taiwan, linking drug-related autopsy and police arrest data from 2010–2019 showed that for every registered (arrested) heroin user, there were 0.7 unregistered users; for methamphetamine, 2.2; for ecstasy, 14.8; for ketamine, 4.9; and for new psychoactive substances (NPS), 174.0. Unregistered individuals were younger, more often female, employed, and had higher blood alcohol levels. About 79% of polydrug use detected at autopsy occurred among unregistered individuals, and 10% had other substance use records differing from those found at death. The approach offers a way to estimate hidden populations, and clinicians should consider possible polydrug use even when single-substance tests are negative.
Study at a glance
| Characteristics | Observational cohort Cross-sectional Peer reviewed |
|---|---|
| Sample size | 1,653 |
| Population | Individuals in Taiwan who died and underwent autopsy with positive drug results (heroin, methamphetamine, ketamine, ecstasy, or NPS) from 2013 to 2019 |
| Duration | 2013 to 2019 for autopsy data; 2010 to 2019 for arrest records |
| Keywords | Accidents Epidemiology Hiv Substance abuse Drug use |
| Citations | 1 |
| Key finding | Unregistered (non-arrested) individuals who use illicit substances substantially outnumber registered (arrested) users for most drug types, especially NPS, and show distinct demographic and toxicological profiles. |
Abstract
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. 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. 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. 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.