Accuracy of Reporting Postpartum Migraine Headaches Coding in Electronic Health Records of a Large Integrated Healthcare System (Preprint)

BACKGROUND Migraine is a common neurological disorder characterized by repeated headaches of varying intensity, particularly during the postpartum period for women. However, due to lack of a validated instrument for uniform case ascertainment on postpartum migraine headache, there is uncertainty in the reported prevalence in the literature. OBJECTIVE To evaluate the completeness and accuracy of reporting postpartum migraine headache coding in health plan electronic health records (EHR) and compare the coding quality before and after implementation of the International Classification of Diseases-Clinical Modification [ICD]-10-CM coding and pharmacy records in EHR. METHODS Medical records of 200 pregnancies delivered in all Kaiser Permanente Southern California (KPSC) hospitals during two time periods: 1/1/2012 - 12/31/2014 (ICD-9-CM coding period) and 1/1/2017 - 12/31/2019 (ICD-10-CM coding period) were randomly selected from EHR for chart review, and postpartum migraine headache cases recorded within one year after delivery were identified. Abstracted clinical records for cases were compared with corresponding diagnosis and pharmacy prescription utilization records for both ICD-9-CM and ICD-10-CM coding periods through comparisons of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), as well as the summary statistics of F-score (F) and Youden’s J Statistic (J). Kappa statistic (K) for interrater reliability were calculated. RESULTS The overall interrater agreement among two chart abstractors for postpartum migraine headache was 100%. Diagnosis coding (F = 87.8%, J = 82.5%) did better than pharmacy records (F = 72.7%, J = 57.5%) when identifying cases, but combining both of these sources of data produced much greater accuracy identification of postpartum migraine cases (F = 96.9%, J = 99.7%). Results were similar across the ICD-9-CM and ICD-10-CM coding periods. CONCLUSIONS Neither diagnostic codes nor pharmacy records alone are sufficient for identifying postpartum migranie cases reliably, but when used together, they are quite reliable. The completeness of data remained similar after the implementation of the ICD-10-CM coding in the EHR system. CLINICALTRIAL Not Applicable.