Validation of an ICD-9-Based Algorithm to Identify Stillbirth Episodes from Medicaid Claims Data

IntroductionIn administrative data, accurate timing of exposure relative to gestation is critical for determining the effect of potential teratogen exposure on pregnancy outcomes.ObjectiveTo develop an algorithm for identifying stillbirth episodes in the ICD-9-CM era using national Medicaid claims data (1999-2014).MethodsUnique stillbirth episodes were identified from clusters of medical claims using a hierarchy that identified the encounter with the highest potential of including the actual stillbirth delivery and that delineated subsequent pregnancy episodes. Each episode was validated using clinical detail on retrieved medical records as the gold standard.ResultsAmong 220 retrieved records, 197 were usable for validation of 1417 stillbirth episodes identified by the algorithm. The positive predictive value (PPV) was 64.0% (57.3-70.7%) overall, 80.4% (73.8-87.1%) for inpatient episodes, 28.2% (14.1-42.3%) for outpatient-only episodes, and 20.0% (2.5-37.5%) for outpatient episodes with overlapping hospitalizations. The absolute difference between the dates of the algorithm-specified stillbirth delivery and the medical record-based event was 4.2 +/- 24.3 days overall, 1.7 +/- 7.7 days for inpatient episodes, 14.3 +/- 51.4 days for outpatient-only episodes, and 1.0 +/- 2.0 days for outpatient episodes that overlapped with a hospitalization. Excluding all outpatient episodes, as well as pregnancies involving multiple births, the PPV increased to 82.7% (76.8-89.8%).ConclusionsOur algorithm to identify stillbirths from administrative claims data had a moderately high PPV. Positive predictive value was substantially increased by restricting the setting to inpatient episodes and using only input diagnostic codes for singleton stillbirths.

Automated summary

An algorithm was developed to identify stillbirth episodes using national Medicaid claims data from 1999 to 2014. The algorithm had a moderately high positive predictive value, which was further increased by restricting the analysis to inpatient episodes and using diagnostic codes for singleton stillbirths.