Perinatal & Pediatric
Validation of ICD-10 diagnosis codes for antepartum iron-deficiency anemia Anna Booman* Anna Booman Sara Siadat Brian Bateman Irogue Igbinosa Elliott Main Deirdre J. Lyell Cecilia Leggett Stephanie Leonard
Iron deficiency anemia during pregnancy increases risk of adverse perinatal health outcomes, with stark racial disparities: prevalence is more than twice as high in Black compared with White pregnant individuals. Modern epidemiologic research largely relies on International Classification of Diseases, Clinical Modification, 10th Revision (ICD-10) diagnosis codes to identify individuals with antepartum anemia, yet their validity remains unknown. Our objective was to assess the validity of ICD-10 codes for antepartum anemia compared with the diagnostic gold standard of hemoglobin or hematocrit measurements. We used commercial insurance claims data from the Merative™ MarketScan® Research Database for pregnancies during 2018-2022. Those with hereditary anemia (e.g., sickle cell) were excluded. Antepartum anemia was defined using clinically recommended hemoglobin and hematocrit thresholds (<11.0 g/dL and <33% in the first and third and <10.5 g/dL and <32% in the second trimester, respectively). We calculated Cohen’s kappa, sensitivity, specificity, positive predictive value, and negative predictive value of the ICD-10 codes. Among 70,752 pregnancies, 30.2% had antepartum anemia based on hemoglobin and hematocrit values and 12.0% had at least one ICD-10 diagnosis code indicating antepartum anemia. Cohen’s kappa between anemia identified through laboratory values and ICD-10 codes was 0.205 (95% confidence interval [CI]: 0.196, 0.215). Sensitivity of the ICD-10 codes was 0.238 (95% CI: 0.233, 0.244); specificity was 0.932 (95% CI: 0.929, 0.934); positive predictive value was 0.602 (95% CI: 0.591, 0.612); and negative predictive value was 0.739 (95% CI: 0.735, 0.742). These findings suggest low sensitivity, but high specificity, of ICD-10 diagnosis codes for antepartum anemia. Researchers should be aware of the limitations of relying solely on ICD-10 codes for antepartum anemia and consider conducting bias analyses when hemoglobin and hematocrit measurements are unavailable.