Validity of ICD-based algorithms to estimate the prevalence of injection drug use among infective endocarditis hospitalizations in the absence of a reference standard

• Published in: Drug and alcohol dependence 2020-04, Vol.209, p.107906-107906, Article 107906
• Main Authors: McGrew, Kaitlin M., Carabin, Hélène, Garwe, Tabitha, Jafarzadeh, S. Reza, Williams, Mary B., Zhao, Yan Daniel, Drevets, Douglas A.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Algorithms; Bayes Theorem; Bayesian analysis; Bias; Classification; Cross-Sectional Studies; Diagnostic error; Diagnostic systems; Diagnostic tests; Drug abuse; Drug use; Endocarditis; Endocarditis - diagnosis; Endocarditis - epidemiology; Female; Health information; Hepatitis; Hepatitis C; Hospitalization; Hospitalization - trends; Humans; Injection; International Classification of Diseases; International Classification of Diseases - standards; Intravenous; Male; Mathematical models; Medical diagnosis; Medical records; Middle Aged; Prevalence; Reference Standards; Reproducibility of Results; Retrospective Studies; Sensitivity; Substance abuse; Substance Abuse, Intravenous - diagnosis; Substance Abuse, Intravenous - epidemiology; Validation studies; Validity; Viruses; Young Adult
• ISSN: 0376-8716; 1879-0046
• DOI: 10.1016/j.drugalcdep.2020.107906

•IDU misclassification varies across ICD algorithms and revisions.•IDU prevalence was overestimated with a combination drug/Hepatitis C algorithm.•ICD-10 codes for drug use had decent sensitivity and nearly perfect specificity.•Analyses of administrative health databases should adjust for misclassification. International Classification of Diseases (ICD) code algorithms are routinely used to estimate the frequency of illicit injection drug use (IDU)-associated hospitalizations in administrative health datasets despite a lack of evidence regarding their validity. We aimed to measure the sensitivity and specificity of ICD code algorithms used to estimate the prevalence of current/recent IDU among infective endocarditis (IE) hospitalizations without a reference standard. We reviewed medical records of 321 patients aged 18–64 years old from an urban academic hospital with an IE diagnosis between 2007 and 2017. Diagnostic tests for IDU included self-reported IDU in medical records; a drug use, abuse and dependence (UAD) ICD algorithm; a Hepatitis C Virus (HCV) ICD algorithm; and a combination drug UAD/HCV ICD algorithm. Sensitivity, specificity and the misclassification error (ME)-adjusted IDU prevalence were estimated using Bayesian latent class models. The combination algorithm had the highest sensitivity and lowest specificity. Sensitivity increased for the drug UAD algorithm in the ICD-10 period compared to the ICD-9 period. The ME-adjusted current/recent IDU prevalence estimated using the drug UAD and HCV algorithms was 23 % (95 % Bayesian credible interval: 16 %, 31 %). The unadjusted prevalence estimate from the drug UAD algorithm underestimated the ME-adjusted prevalence, while the combination algorithm overestimated it. The validity of ICD code algorithms for IDU among IE hospitalizations is imperfect and differs between ICD-9 and ICD-10. Commonly used ICD-based algorithms could lead to substantially biased prevalence estimates in IDU-associated hospitalizations when using administrative health data.