Development of a Pregnancy Cohort in Commercial Insurance Claims Data: Evaluation of Deliveries Identified From Inpatient Versus Outpatient Claims.

Purpose: Studies using insurance claims data to identify pregnancies are rarely able to directly assess the validity of the pregnancy/delivery. Inpatient versus outpatient delivery claims may provide different levels of evidence, but more stringent requirements could result in exclusion of true pregnancies. We identified delivery codes from the inpatient and outpatient settings and examined possible confirmatory evidence suggesting that a delivery truly occurred.

Methods: Using a US commercial insurance database (2006-2021), we identified potential pregnancies by presence of delivery claims from a provider and/or facility. We classified deliveries as inpatient (claim date during inpatient admission) or outpatient (claim date not during inpatient admission). We identified possible confirmatory evidence for each delivery including: (1) Presence of both provider and facility delivery codes; (2) presence of both diagnosis and procedure delivery codes; (3) labor and delivery revenue codes; (4) gestational age diagnosis codes; (5) pregnancy-related care codes; (6) linkage to an infant claim; and (7) infant insurance enrollment and linkage to a birthing parent. We quantified the proportion of deliveries with confirmatory evidence by delivery setting. Among deliveries with ≥ 1 piece of confirmatory evidence, we compared patient characteristics by apparent delivery setting.

Results: Among 4 084 474 delivery episodes, 96.4% were classified as inpatient and 3.6% outpatient. 99.9% of inpatient and 94.0% of outpatient deliveries had ≥ 1 piece of confirmatory evidence. Pregnancy-related care codes were the most common type of confirmatory evidence (99.0% inpatient, 85.7% outpatient). Deliveries classified as inpatient occurred among patients who were older and more clinically complex (i.e., more pregnancy complications, chronic diseases, and prescription medications).

Conclusions: The vast majority of deliveries had confirmatory evidence regardless of apparent setting. Patient characteristics differed by delivery setting. Inclusion of apparent outpatient deliveries may increase the sample size of the study population and improve the generalizability of study results.