Mortality of New York children with sickle cell disease identified through newborn screening

Abstract

Purpose: Long-term follow-up of newborn screening for conditions such as sickle cell disease can be conducted using linkages to population-based data. We sought to estimate childhood sickle cell disease mortality and risk factors among a statewide birth cohort with sickle cell disease identified through newborn screening.

Methods: Children with sickle cell disease identified by newborn screening and born to New York residents in 2000-2008 were matched to birth and death certificates. Mortality rates were calculated (using numbers of deaths and observed person-years at risk) and compared with mortality rates for all New York children by maternal race/ethnicity. Stratified analyses were conducted to examine associations between selected factors and mortality.

Results: Among 1,911 infants with sickle cell disease matched to birth certificates, 21 deaths were identified. All-cause mortality following diagnosis was 3.8 per 1,000 person-years in the first 2 years of life and 1.0 per 1,000 person-years at ages 2-9 years. The mortality rate was significantly lower among children of foreign-born mothers and was significantly higher among preterm infants with low birth weight. The mortality rates were not significantly higher for infants after 28 days with sickle cell disease than for all New York births, but they were 2.7-8.4 times higher for children 1 through 9 years old with homozygous sickle cell disease than for those of all non-Hispanic black or Hispanic children born to New York residents.

Conclusion: Estimated mortality risk in children with homozygous sickle cell disease remains elevated even after adjustment for maternal race/ethnicity. These results provide evidence regarding the current burden of child mortality among children with sickle cell disease despite newborn screening.Genet Med 17 6, 452-459.

Figure 1. Comparison of mortality rate (per 1,000 person-years (PYs)) among New York children born in 2000–2008 with HbSS or HbSβ⁰ by maternal nativity (US born, foreign born) and age group (overall: 0–9 years; infancy: <1 year; post infancy: 1–9 years)

Stratified by (a) birth weight (<2,500 g or ≥2,500 g) and (b) maternal race/ethnicity (non-Hispanic (NH) white, NH black, Hispanic). *A statistically significant difference was found between low birth weight and normal birth weight. N, number of deaths in each category; Zero rate, resulted from zero deaths.