Evaluating variation between states in algorithms used for identifying abortions in Medicaid claims data.

OBJECTIVES: To evaluate the variability in abortion identification across four published algorithms using Medicaid claims data in states where abortion is covered by Medicaid for all indications. STUDY DESIGN: We analyzed 2020 Medicaid Transformed Medicaid Statistical Information System Analytic Files (TAF) from 14 states with Medicaid abortion coverage. Female recipients aged 15-44 were included. Four previously published algorithms, each using different combinations of diagnosis, procedure (CPT/HCPCS), and medication (NDC) codes, were applied to identify abortion-related claims. For each algorithm, we calculated the number of identified abortions by state and examined variability in identification patterns and code types. RESULTS: Among 9.67 million Medicaid enrollees, the number of identified abortions varied substantially by algorithm and state. The max-to-min ratio across algorithms was lowest in Hawaii (2.09) and highest in New Jersey (138.59). Algorithms differed in their use of diagnosis-only, procedure-only, or both code types, with the proportion of claims containing both codes ranging from 0.4% (New Jersey) to 86.2% (Vermont). Abortions identified solely by HCPCS codes for mifepristone or misoprostol varied from 0.1% to 32.6% by state. No algorithm consistently performed well across all states. CONCLUSION: Substantial heterogeneity exists in the performance of abortion-identifying algorithms across states. These differences likely reflect variation in billing practices, Medicaid data reporting, and algorithm construction. IMPLICATIONS: Researchers should exercise caution when using claims data to estimate abortion rates, particularly across multiple states. Validation of an algorithm using health record data is needed.

Duke Scholars

Author Jonas J Swartz Obstetrics and Gynecology, Women's Community & Population He ...