Newborn sickle cell disease screening: the Jamaican experience (1995–2006)

Sickle cell disease: the need for a public health agenda

Sickle cell disease (SCD) is a collection of inherited blood disorders that affect a substantial number of people in the U.S., particularly African Americans. People with SCD have an abnormal type of hemoglobin, Hb S, which polymerizes when deoxygenated, causing the red blood cells to become misshapen and rigid. Individuals with SCD are at higher risk of morbidity and mortality from infections, vaso-occlusive pain crises, acute chest syndrome, and other complications. Addressing the public health needs related to SCD is an important step toward improving outcomes and maintaining health for those affected by the disorder. The objective of this study was to review public health activities focusing on SCD and define the need to address it more comprehensively from a public health perspective. We found that there has been some progress in the development of SCD-related public health activities. Such activities include establishing newborn screening (NBS) for SCD with all states currently having universal NBS programs. However, additional areas needing focus include strengthening surveillance and monitoring of disease occurrence and health outcomes, enhancing adherence to health maintenance guidelines, increasing knowledge and awareness among those affected, and improving healthcare access and utilization. These and other activities discussed in this paper can help strengthen public health efforts to address SCD.

Stroke recurrence in children with sickle cell disease treated with hydroxyurea following first clinical stroke

Chronic transfusion therapy is the treatment of choice for preventing stroke recurrence in children with sickle cell disease (SCD). The majority of children affected by this devastating complication live in the developing world where access to regular blood transfusions may be impractical. Since 2000, in the absence of regular blood supplies, all children at the Sickle Cell Unit who had experienced a first clinical stroke were offered hydroxyurea (HU) as the only intervention to prevent stroke recurrence. Forty-four children were identified as having experienced a first clinical stroke between January 1, 2000 and September 30, 2009; one died at that presentation. Forty-three children were therefore followed for 111 person-years, of whom 10 (23.3%) agreed to start HU. Only one child in the HU group, incidence rate 2/100 person-years, had clinical stroke recurrence, compared to 20/33 in the non-HU group, incidence rate 29/100 person-years (Hazard ratio (HR) 9.4 [95% Confidence interval (CI): 1.3-70.6]; P = 0.03). When the groups were compared, in the non-HU group, four died (vs. zero), 13 (53% vs. 10%) had moderate-severe physical disability (P = 0.017), and 12 (44% vs. 20%) required special education or were too disabled to attend school. Our data support the role of HU as a useful intervention for prevention of stroke recurrence in SCD when transfusion programs are not available or practical.

Neonatal screening for hemoglobinopathies: results of a public health system in South Brazil

AIM

The aim of this study was to estimate the prevalence of hemoglobinopathies in South Brazil.

METHODS

Samples of dried blood spots collected by heel prick in neonates were evaluated by isoeletric focusing and/or high-performance liquid chromatography techniques. All variants were characterized at the molecular level.

RESULTS

A total of 437,787 samples were evaluated. Among these, 6391 showed an abnormal hemoglobin pattern. These included 48 cases (0.01%) of sickle cell disorders (33 hemoglobin SS [Hb SS], 7 Hb SC, 7 Hb S/beta thalassemia, 1 Hb SD), 1 neonate who was homozygous for beta thalassemia, 6272 (1.4%) newborns who were heterozygous for Hb S, C, or D, and 71 (0.02%) neonates who were carriers for rare hemoglobin variants. Most of these rare variants were identified for the first time in Brazil.

CONCLUSIONS

Comparing these results with those obtained in other Brazilian regions, we observe a highly heterogeneous distribution. This knowledge is useful in healthcare planning and allocation of resources, as well as identifying at-risk couples, which will assist with disease prevention.

Population estimates of sickle cell disease in the U.S

BACKGROUND

The number of individuals with sickle cell disease (SCD) in the U.S. is unknown. Determination of burden of disease, healthcare issues, and policies is best served by representative estimations of the SCD population.

PURPOSE

To update SCD population estimates by using recent U.S. Census and birth-cohort SCD prevalence for at-risk populations as available through the centralized reporting of universal newborn screening for hemoglobinopathies, with an effort to demonstrate the potential effect of early mortality.

METHODS

National and state SCD populations were estimated based on the 2008 U.S. Census, using total, African-American, and Hispanic birth-cohort disease prevalence derived from the National Newborn Screening Information System. Estimates were corrected for early mortality for sickle cell anemia using data from the CDC's Compressed Mortality Report and published patient-cohort survival information.

RESULTS

National SCD population estimates ranged from 104,000 to 138,900, based on birth-cohort disease prevalence, but from 72,000 to 98,000 when corrected for early mortality. Several limitations were noted in the available data, particularly for SCD mortality in adults.

CONCLUSIONS

The number of individuals with SCD in the U.S. may approach 100,000, even when accounting for the effect of early mortality on estimations. A paucity of high-quality data limits appropriate estimation. State-to-state variability may preclude application of state-specific information to other states or to the nation as a whole. Standardized collection and centralized reporting, a surveillance system, will be necessary to assess the size and composition of the U.S. SCD population.