Despite an increase in the early part of the century, there has been a decline in necrotizing enterocolitis (NEC) death among infants in the US in recent years.¹

A team, led by Mattie F. Wolf, MD, Division of Neonatology, Department of Pediatrics, Emory University School of Medicine and Children’s Healthcare of Atlanta, analyzed yearly trends in NEC-related infant mortality rates from 1999-2020, as well as specific rates based on race and region in the US.

A Common Cause of Death

NEC is currently the most common cause of death for extremely preterm infants between 2 weeks and 2 months of age.The incidence rate is also noted as the only cause of death in this age range that increased from 2000-2011. However, another study saw a decrease in incidence between 2006-2017.

Overall, there is a need for population-based trends for NEC-related infant mortality rates, as well as specific racial and geographic analysis.

In the cohort study, the investigators looked at data from the US Centers for Disease Control and Prevention (CDC) and National Center for Health Statistics’ 2020 Final Multiple Cause of Death Data to evaluate all infant deaths up to 1 year of age with an underlying cause of NEC of newborn.

The Data

Overall, the team evaluated 88.1 million live births from 1999-2020 and found 8951 infants died from NEC (overall NEC-IMR across all years, 10.2 per 100,000 live births; 95% confidence interval [CI], 10.0-10.4) (For 2020, Black: 16.1; 95% CI, 13.1-19.2 per 100,000; White: 6.4; 95% CI, 5.5-7.4 per 100,000).

There was a decline of 7.7% (95% CI, 2.1-13.0%) per year from 2007-2012, with no significant decline thereafter. Ultimately in the mortality rate was at its highest in 2005 at 13.2 deaths per 100,000 live births (95% CI, 12.1-14.3) and at its lowest in 2020 at 8.3 deaths per 100,000 live births (95% CI, 7.4-9.3).

Segmented lines were not parallel for Black infants compared with White infants (P = .04 from test of parallelism) and the Black-to-White NEC-related infant mortality rate ratio declined from 4.2 deaths per 100,000 live births in Mississippi in 1999 to 4.4 deaths per 100,000 live births in Iowa (95% CI, 3.1-6.0). The Black-to-White NEC-related infant mortality rate ratio across all years by state ranged from 1.8-5.8 and there was no association found between a specific state’s overallNEC-related infant mortality rate and the Black-to-White NEC-related infant mortality rate ratio.

Overall, the results were similar to what has been found in the past.

“This cohort study is compatible with findings from prior reports showing both increases and subsequent decreases in NEC-related deaths,” the authors wrote. “Additionally, striking differences in Black-to-White NEC-(infant mortality rate] decreased over time, and a state’s Black-to-White ratio was unrelated to its NEC-[infant mortality rate]. Racial differences mirror overall disparity in [infant mortality rate]. Further studies are warranted to examine factors mediating these changes, including the role of increasing donor human milk use.”

There were various limitations of the study, including potential misclassifications for causes of death, the exclusion of some states because of small numbers, and a lack of disease classification beyond an ICD-10 diagnosis.

References:

Wolf MF, Rose AT, Goel R, Canvasser J, Stoll BJ, Patel RM. Trends and Racial and Geographic Differences in Infant Mortality in the United States Due to Necrotizing Enterocolitis, 1999 to 2020. JAMA Netw Open. 2023;6(3):e231511. doi:10.1001/jamanetworkopen.2023.1511