Using ICD Codes Alone May Misclassify Overdoses Among Perinatal People

As perinatal drug overdoses continue to rise, reliable approaches are needed to monitor overdose trends during pregnancy and postpartum. This analysis aimed to determine the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ICD-9/10-CM codes for drug overdose events among people in the MATernaL and Infant clinical NetworK (MAT-LINK) with medication for opioid use disorder (MOUD) during pregnancy. People included in this analysis had electronic health record (EHR) documentation of MOUD and a known pregnancy outcome from January 1, 2014 through August 31, 2021. Data were analyzed during pregnancy through one year postpartum. CDC's drug overdose case definitions were used to categorize overdose based on ICD-9/10-CM codes. These codes were compared to abstracted EHR data of any drug overdose. Analyses were conducted between May 2023 and May 2024. Among 3,911 pregnancies with EHR-documented MOUD, the sensitivity of ICD-9/10-CM codes for capturing drug overdose during pregnancy was 32.7%, while specificity was 98.5%, PPV was 23.4%, and NPV was 99.0%. The sensitivity of ICD-9/10-CM codes for capturing drug overdose postpartum was 30.9%, while specificity was 98.4%, PPV was 25.9%, and NPV was 98.8%. The sensitivity and PPV of ICD-9/10-CM codes for capturing drug overdose compared to abstracted EHR data during the perinatal period was low in this cohort of people with MOUD during pregnancy, though the specificity and NPV were high. Incorporating other data from EHRs and outside the healthcare system might provide more comprehensive insights on nonfatal drug overdose in this population.