Prevalence of sickle cell disease, hemoglobin S, and hemoglobin C among Haitian newborns

Abstract

Sickle Cell Disease (SCD) has historically been a significant contributor to childhood mortality worldwide. In the 1960s, the average lifespan of a person with SCD in the United States was less than 15 years 1. In the developed world, childhood mortality from SCD has decreased in part due to blood transfusions, vaccinations 2, prophylactic antibiotics 3, hydroxyurea, and hematopoietic cell transplant. Newborn screening is essential for effective targeted interventions, including antibiotic prophylaxis and appropriate vaccination. In developing world settings where SCD is highly prevalent, the disease contribution to mortality is likely to be significant. To reduce childhood mortality attributable to SCD, accurate prevalence data must be obtained. These data can be used to inform newborn screening program planning. In the Republic of Haiti, no universal screening program for SCD yet exists. Further, no study to date has directly measured the prevalence of SCD among newborns in Haiti, and the true prevalence of disease and its subsequent impact on the healthcare system remain unknown. Two previous studies have attempted to indirectly determine SCD prevalence. One study reported the prevalence of hemoglobinopathy traits (hemoglobin S and hemoglobin C) among infant children of recent Haitian immigrants to Miami, United States at 8.0% and 4.7%, respectively 4. However, this study did not have enough participants to draw general conclusions about the prevalence of SCD, and did not determine paternal ethnicity. Another study in healthy adult volunteers in a population in Northern Haiti found the prevalence of hemoglobin S to be 15.5%, with no differentiation between SCD and trait 5. We have performed a study of hemoglobin identification (the largest of its kind, to our knowledge) using high performance liquid chromatography (HPLC) in consecutive live births in Port-au-Prince to better understand the prevalence of SCD in Haiti. In 2010, at the Saint Damien Children's Hospital in Tabarre, Port-Au-Prince, Haiti, 2459 consecutive newborns were screened for detection of Sickle Hemoglobin. These children were born to mothers who lived within Port-au-Prince, and in outlying areas. Mothers of newborn patients gave verbal consent to blood draws. Heel-prick specimens were obtained and placed on filter paper (S&S 903, Schleicher & Schuell, NH) and sent to Pordenone Hospital, Italy. Hemoglobin screening for types F, A, S, and C was carried out via high performance liquid chromatography using the Variant HPLC system (Bio-Rad Laboratories, CA), then Variant NBS HPLC system (Bio-Rad Laboratories, CA). Among 2459 screened neonates, 2258 specimens could be tested. Due to technical issues with samples, 201 could not be tested. Of the 2258 samples tested, 247 had HbFAS, 57 had HbFAC, 10 had HbFS, and 3 had HbFSC. This yields a prevalence (95% confidence interval) of 10.9% (9.7–12.2%), 2.5% (1.9–3.2%), 0.44% (0.17–0.72%), and 0.13% (0–0.28%), respectively (Fig. 1). This corresponds to a prevalence of the sickle cell disease genotypes HbSS and HbSC of 1 in 173 newborns. The prevalence of SCD in Haitian newborns appears to be greater than twice that among African Americans in the United States 6. This represents a significant burden to the healthcare system. Results of this study represent the only large-scale direct measurement of SCD performed inside Haiti. Our study population was confined to a large single hospital in an urban setting; however, results obtained from this study were not largely different from the data collected in Miami or Northern Haiti. Using a team based approach, this pilot project has demonstrated that screening for SCD in a hospital population is feasible and will yield a significant number of cases. Challenges will exist in expanding this project within St. Damien, and to smaller hospitals in more remote settings, and carrying out HPLC testing locally. Further, given that 78% of children in Haiti are born outside of hospitals, challenges to universal screening remain substantial. The high prevalence of sickle cell disease reported in this study suggests that a national newborn screening program with comprehensive care of found cases is warranted, and may contribute to a significant decrease in child mortality and morbidity in the Republic of Haiti. Seth Rotz1* Genevieve Arty2 Roberto Dall'Amico3 Lucia De Zen4 Francesco Zanolli5 Prasad Bodas6 1Department of Pediatrics and Department of Internal Medicine Rainbow Babies and Children's Hospital University Hospitals Case Medical Center, Cleveland, Ohio2NPH Saint Damien Hospital/Nos Petits Freres et Soeurs, ouest Port-au-Prince, Haiti3Azienda Ospedaliera “S.M.D.Angeli” SOC Pediatria, Pordenone, Italy4Azienda Ospedaliera “S.M.D.Angeli” SOC Pediatria, Pordenone, Italy5Azienda Ospedaliera “S.M.D.Angeli”, Serv. Immuno-trasf, Pordenone, Italy6Akron Childrens Hospital, Department of Pediatrics, Division of Hematology/Oncology, Akron, Ohio