Intraventricular Hemorrhage-Associated Mortality Rates Associated with Extremely Premature Births in a Large Medical Records Database in the United States

Introduction Infants born extremely premature (EP) (<28 weeks’ gestational age [wGA]) are at increased risk for complications, including germinal matrix hemorrhage-intraventricular hemorrhage (GMH-IVH [grades I–III]) or periventricular hemorrhagic infarction (also known as grade IV). The aim of this study was to assess the incidence of IVH and associated mortality rates among EP infants in the US.

Materials and Methods We conducted a population-based cohort study of live born EP infants recorded in the electronic medical records database of Kaiser Permanente Northern California between 1997 and 2016. Infants with major congenital malformations, and those born <22 wGA, were excluded. Outcomes included IVH and other complications associated with EP births (bronchopulmonary dysplasia [BPD] and retinopathy of prematurity [ROP]), and mortality rates at 2 years of age. International Classification of Diseases, Ninth/Tenth Revision, Clinical Modification (ICD-9-CM/ICD-10-CM), was used to identify IVH (by grade). Mortality was analyzed by GA group. Cox proportional hazard model was applied to calculate the hazard ratios (HR) and 95% confidence interval (CI).

Results Among 704,989 live births, a total of 2,154 (0.31%) infants met the study definition of EP. IVH was present in 489 (22.7%) of EP infants. Of those, 11.7% (57/489) and 16.6% (81/489) had grade III and grade IV IVH, respectively. The cumulative mortality rate (birth to 2 years) among children born EP and diagnosed with IVH (any grade) (with or without other complication) was 29.9%; cumulative mortality among children with grade III or IV IVH was 54.4% (grade III: 35.1%; grade IV: 67.9%). Mortality decreased with increasing GA group ([Table A006]). Among EP infants with IVH only (without BPD or ROP) who survived to 36 weeks (n = 59), 5.1% subsequently died. Among children with grade III or IV IVH, the (crude) HR for mortality was 2.97 (95% CI: 2.29–3.86), versus children with no IVH diagnosis; after controlling for GA, birth weight, maternal age, and select comorbidities, the adjusted HR was 1.75 (95% CI: 1.32–2.31).

Conclusion IVH is a major complication of EP birth. The mortality rate among EP infants with IVH is high, particularly among infants with grade III or IV IVH.

Table A006

	Cumulative mortality rate (at 2 years of age)
	IVH (all grades) % (deaths/children)	IVH grade III or IV % (deaths/children)
22 to <24 wk	76.1% (35/46)	85.7% (18/21)
24 to <26 wk	37.3% (78/209)	50.6% (39/77)
26 to <28 wk	14.1 (33/234)	45.0% (18/40)

Conflict of Interest

None declared.

Die Autoren geben an, dass kein Interessenkonflikt besteht.