P3.E096: Prevalence of Neonatal Abstinence Syndrome Among Infants Born to Pregnant People with an Opioid Use Disorder – Seven Clinical Sites, 2014-2021

Background: Neonatal abstinence syndrome (NAS) is a group of conditions that can occur when newborns withdraw from certain substances, including opioids, that they were exposed to before birth. There is considerable variation in the clinical diagnosis of NAS, and ways in which health departments conduct surveillance, leading to a wide range of prevalence estimates. We used data from the MATernaL and Infant clinical NetworK (MAT-LINK), a sentinel surveillance system of pregnant person and child dyads reported in electronic health records (EHR) at U.S. clinical sites to understand how prevalence estimates of NAS might differ under different surveillance and clinical case definitions for infants born to pregnant people with an opioid use disorder (OUD).

Methods: Pregnant person and infant dyads with a live birth occurring between January 1, 2014 and August 31, 2021 from 7 clinical sites were included in this analysis (N=5,025). We estimated the prevalence of infants with NAS based on four case definitions: 1) Council of State and Territorial Epidemiologists (CSTE) 2023 NAS Tier 1 standardized surveillance case definition based on withdrawal signs, an NAS diagnosis or chief complaint, maternal history of substance use, and laboratory evidence, 2) Neonatal opioid withdrawal syndrome (NOWS) clinical case definition based on in utero exposure to opioids and withdrawal signs, 3) ICD codes (P96.1, 779.5), 4) whether the EHR indicated a chief complaint of NAS or NOWS. A sensitivity analysis was also conducted among dyads with complete information for the elements included in all case definitions to explore overlap in case definitions (N=2,748).

Results: Overall NAS prevalence in this cohort of pregnant people with OUD ranged from 52% to 66% depending on the case definition used. NAS prevalence was 66% using the CSTE NAS case definition (1,808/2,748), 65% using the NOWS clinical case definition (1,944/2,978), 62% using chief complaint in the EHR (2,666/4,274), and 52% using ICD-9 and ICD-10 codes (2,588/5,025). When restricting to those with complete information on all case definitions, estimates were similar. Additionally, among infants with complete information indicating at least one case definition for NAS, 68% were identified by two or more case definitions.

Conclusion: Prevalence estimates of NAS varied slightly by case definitions, with substantial overlap noted. EHR ICD code-based case definitions may underestimate the prevalence of NAS, indicating that further work may be needed to standardize case definitions and reporting of this condition to understand its true prevalence and burden. It is important that diagnoses, other clinical information, and ICD codes are recorded in EHRs for all cases to ensure that impacted families can be identified and referred to support services.