Declared and undeclared substance use among emergency department patients: a population‐based study

Aims To estimate both self-reported and corrected prevalences of substance use in a population-based study of general hospital emergency department (ED) patients and predict undeclared use. Design A state-wide cross-sectional, two-stage probability sample survey that incorporates toxicological screening. Setting Seven Tennessee EDs in acute care, adult, civilian, non-psychiatric hospitals. Participants A total of 1502 Tennessee residents, 18 years of age and older, possessing intact cognition, able to give informed consent and not in police custody. Measurements Prevalence of self-reported current substance use by age, sex and type with correction for underreporting based on toxicological screening. Covariates in the multivariate analysis of undeclared use were sociodemographics, ED visit circumstances, health-care coverage, prior health status and treatment history and tobacco addiction. Findings Declared current use was highest for alcohol (females 26%, males 47%), marijuana (males 11%, females 6%) and benzodiazepines (females 10%, males 7%). After correction for under-reporting, overall use for any of the eight targeted substances rose from 44% to 56% for females and 61% to 69% for males. Largest absolute changes involved opioids, benzodiazepines, marijuana, amphetamines and/or methamphetamine, with little change for alcohol. Patients aged 65 years and older manifested excess undeclared use relative to patients aged 18‐24 years, as did patients not reporting tobacco addiction or receiving substance abuse treatment. Conclusion Adjustment for under-reporting produced minimal change in the estimated prevalence of alcohol use. However, toxicological screening markedly increased estimates of other drug use, especially for the elderly, who may under-report medication use. Screening tests are useful tools for detecting undeclared substance use.