Survival of children with sickle cell disease

Abstract

Contemporary survival data are not available for children with sickle cell disease (SCD). The few previous childhood SCD cohort studies do not reflect the benefits of modern therapy. We defined an inception cohort of newborns with sickle cell anemia (SS), sickle-beta degrees -thalassemia (S beta degrees ), sickle-hemoglobin C disease (SC), or sickle-beta(+)-thalassemia (Sbeta(+)) who were identified by newborn screening and followed for up to 18 years. The incidence of death and stroke were calculated. Overall survival, SCD-related survival (considering only SCD-related deaths), and strokefree survival were determined. The 711 subjects provided 5648 patient-years of observation. Twenty-five subjects died; mean age at death was 5.6 years. Five patients died from infection. Thirty had at least one stroke. Among SS and Sbeta degrees subjects (n = 448), the overall rates of death and stroke were 0.59 and 0.85/100 patient-years. Survival analysis of SS and Sbeta degrees subjects predicted the cumulative overall, SCD-related, and stroke-free survival to be 85.6%, 93.6%, and 88.5% by 18 years of age. No SCD-related deaths or strokes occurred in SC or Sbeta(+) subjects (n = 263). Childhood mortality from SCD is decreasing, the mean age at death is increasing, and a smaller proportion of deaths are from infection.

Figures

Figure 1. Survival of children with SS and Sβ°

Shown are overall survival (A), SCD-related mortality (B), and stroke-free survival (C). Numbers above the x-axes indicate the number of subjects remaining at risk at a particular age. Dotted lines delimit the 95% CIs. (D) Overall survival curves for the Jamaican cohort study of SCD (SS only), the CSSCD infant cohort (SS only), and the Dallas Newborn Cohort (SS and Sβ°). Vertical bars indicate upper or lower boundaries of the 95% CIs (one direction omitted for clarity). The survival curve for the CSSCD infant cohort was published for approximately 4 years of observation only. The Jamaican cohort was divided into thirds based on date of birth. Subjects in the first third (1973–1975) did not routinely receive prophylactic PCN, whereas subjects in the middle (1975–1979) and last (1979–1981) thirds did receive PCN. Survival curves are shown only for the first and last third of the Jamaican cohort.