{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T06:14:05Z","timestamp":1786947245323,"version":"build-2736575974"},"reference-count":23,"publisher":"BMJ","issue":"9","funder":[{"name":"Ministry of Justice, Taiwan","award":["112-1301-10-28-01"],"award-info":[{"award-number":["112-1301-10-28-01"]}]},{"name":"Ministry of Justice, Taiwan","award":["113-1301-10-28-03"],"award-info":[{"award-number":["113-1301-10-28-03"]}]},{"DOI":"10.13039\/501100004737","name":"National Health Research Institutes","doi-asserted-by":"publisher","award":["NHRI-EX114-11420NC"],"award-info":[{"award-number":["NHRI-EX114-11420NC"]}],"id":[{"id":"10.13039\/501100004737","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["J Epidemiol Community Health"],"accepted":{"date-parts":[[2025,4,11]]},"published-print":{"date-parts":[[2025,9]]},"abstract":"<jats:sec>\n                  <jats:title>Background<\/jats:title>\n                  <jats:p>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.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods<\/jats:title>\n                  <jats:p>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.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>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.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>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.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1136\/jech-2025-223903","type":"journal-article","created":{"date-parts":[[2025,4,23]],"date-time":"2025-04-23T13:20:20Z","timestamp":1745414420000},"page":"719-725","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":2,"title":["Detection of hidden populations using illicit substances"],"prefix":"10.1136","volume":"79","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3704-2434","authenticated-orcid":false,"given":"Shyh-Yuh","family":"Wei","sequence":"first","affiliation":[{"name":"Department of Psychiatry, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Brian Meng-Hsun","family":"Li","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Institute of Clinical Pharmacy and Pharmaceutical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan"},{"name":"Population Health Data Centre, National Cheng Kung University, Tainan, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2825-6740","authenticated-orcid":false,"given":"Hsuan-Yun","family":"Hu","sequence":"additional","affiliation":[{"name":"Forensic Pathology Division, Institute of Forensic Medicine, Ministry of Justice, New Taipei City, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2841-0338","authenticated-orcid":false,"given":"Daniel Hsiang-Te","family":"Tsai","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Institute of Clinical Pharmacy and Pharmaceutical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan"},{"name":"Population Health Data Centre, National Cheng Kung University, Tainan, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Swu-Jane","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Pharmacy Administration, University of Illinois Chicago, Chicago, Illinois, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Szu-Yu","family":"Lin","sequence":"additional","affiliation":[{"name":"Forensic Pathology Division, Institute of Forensic Medicine, Ministry of Justice, New Taipei City, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chien-Chou","family":"Su","sequence":"additional","affiliation":[{"name":"Clinical Innovation and Research Centre, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1231-9345","authenticated-orcid":false,"given":"Chih-Hsin","family":"Pan","sequence":"additional","affiliation":[{"name":"Forensic Pathology Division, Institute of Forensic Medicine, Ministry of Justice, New Taipei City, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Edward Chia-Cheng","family":"Lai","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Institute of Clinical Pharmacy and Pharmaceutical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan"},{"name":"Population Health Data Centre, National Cheng Kung University, Tainan, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2025,4,23]]},"reference":[{"key":"2025100303360096000_79.9.719.1","unstructured":"United Nations Office on Drugs and Crime . 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Royal College of Psychiatrists London; 2011."},{"key":"2025100303360096000_79.9.719.9","doi-asserted-by":"publisher","DOI":"10.1111\/j.1360-0443.1997.tb02893.x"},{"key":"2025100303360096000_79.9.719.10","doi-asserted-by":"crossref","DOI":"10.3389\/fpsyt.2018.00457","article-title":"Hidden Drug Abuse in Hong Kong: From Social Acquaintance to Social Isolation","volume":"9","author":"Tam","year":"2018","journal-title":"Front Psychiatry"},{"key":"2025100303360096000_79.9.719.11","first-page":"222","volume-title":"Results from the Swiss Hidden Population Study. 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