Developing a multi-phase claims-based algorithm to facilitate the study of drug exposure during pregnancy

Document Type

Conference Proceeding

Publication Date


Publication Title

Arthritis Rheum


Background/Purpose: The use of antirheumatic medications during pregnancy may lead to birth defects or other complications. Safety studies are critical, with registries being common but often yielding a small number of cases after years of follow-up. Medical administrative claims data can be used to study large numbers of women and infants more quickly and efficiently, if these claims data accurately identify: pregnancy outcomes, gestational age, drug exposure by trimester and mother/infant links. No single existing algorithm uses only administrative claims data to measure all of these variables. The objective is to develop a multi-phase algorithm for use in administrative medical claims data to identify live/non-live pregnancy outcomes (phase 1), estimate gestational age (phase 2), estimate drug exposure by trimester (phase 3) and link claims data for mothers and infants (phase 4).

Methods: A multi-phase algorithm is being developed in a phased manner among women aged ≥15 and ≤50 years with ≥1 International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) end of pregnancy code. Women were enrolled and had prescription coverage 340 days prior to the end of pregnancy in the Henry Ford Health System between 1/1/2013 and 9/30/2015. In all phases, algorithms will be developed, applied to claims data and compared to electronic medical records for validation. Positive predictive value (PPV), sensitivity and 95% CI will be calculated. The best performing algorithm developed in each phase will be used to move to the next phase.

Results: A total of 698 women met inclusion criteria. Three algorithms were developed and tested for phase 1. Algorithm 1 (≥1 definitive ICD-9-CM end of pregnancy code) performed best (Table 1). Two algorithms for phase 2 were developed and tested. Algorithm 2 (adjusted delivery date based on selected procedure codes and assigned 245 days to preterm, 273 days to term, and 294 days to post-term) performed best for preterm and term births (Table 2).

Conclusion: End of pregnancy outcomes can be identified in claims data with high PPV and sensitivity. Gestational age can be estimated with reasonable PPV and sensitivity for preterm and term live births. Further analyses are underway for phases 3 and 4.




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