Determinants Of Mortality and Survival In Children With Sickle Cell Disease (SCD) In Sub Saharan Africa

In Africa, the natural history of SCD is often assumed to be same to the African Diaspora in the US, Jamaica, Europe or Latin America. Yet the environment can be different, including different pathogen exposure, such as malaria. To help better understand this, over 2000 references were identified using the names of all current or past names of African continent countries and the truncated word sickl$, followed by secondary nested and cross reference searches. Six cases series describing causes of death were identified, representing 182 children (Ndugwa, 1973, Athale, 1994, Koko, 1998, Diagne, 2000, Rahimy, 2003, Van-Dunem, 2007). Gender was reported in 172, 73 were female (42%). Age was reported in 118, 52 were < 5 years (44%). Four studies described some impediment to care or arrival for care in extremis in1/4 to over ½ of patients that died. In Uganda, 9/12 (75%) patient died at home. In Gabon 6/23 (26%) patients died within 4 hours of reaching the hospital and 11/23 (48%) within 24 hours. In Benin 2/10 (20%) died of splenic sequestration diagnosed at home; 38/64 (53%) of patients in Mozambique that died, lived outside of the capital. Causes of death were identified in 146 individuals. These included: fever/sepsis: n=59 (40%), including meningitis: n=15 (10%) and pyelonephritis: n=2 (1%); acute anemia: n=43 (29%), including spleen sequestration: n=28 (19%) and aplastic anemia: n=8 (5%); pain: n=22 (15%); acute chest syndrome/pneumonia: n=18 (12%); CNS: n=8 (5%), including stroke: n=4 (3%), seizure/ coma: n=5 (3%); liver disease: n=5 (3%) including hepatitis: n=3 (2%); Other: n=19 (13%) including wasting/ malnutrition: n=7 (5%), heart failure/cardiomyopathy: n=4 (3%), diarrhea and vomiting: n=3 (2%), transfusion reaction: n=2 (1%). Infectious pathogens were identified in 26, including malaria: n=10 (38%), S. pneumoniae: n=3 (12%), Salmonella: n=2 (8%), H. influenza, Klebsiella and Citrobacter: n=1 (4%) each; viral agents were reported in n=8 (31%) including HBV: n=5 (19%), HIV: n=3 (12%). Reported general population hemoglobinopathy surveys after birth revealed the following Relative Risk (RR) of observing individuals with hemoglobin SS compared to Hardy Weinberg expected frequencies (some age cohorts overlap; Tanzania '56, Benin '09, Burkina Faso '70, Central African Republic'75, Gabon'65/'80, Gambia'56, Ghana '56/‘57/'00/'10, Kenya '04/'10, Malawi '72/'00/'04, Mozambique '86, Nigeria '56/'70/'79/'81/'84/'05, Senegal '69, Sierra Leone '56). Age 0-1 years, total n=2112 observed n=22 (1.0%), expected n=16.5 (0.8%), RR=1.3 (95% CI=0.7,2.5), p=0.441. Age 0-6 years, total n=4078; observed n=39 (1.0%); expected n=40.6 (1.0%); RR=1.0 (95% CI=0.6,1.5), p=0.925. Age 5-19 years, total n=1880; observed n= 5 (0.3%); expected n= 24.8 (1.3%); RR=0.2 (95% CI=0.1,0.5); p<0.001. Adults, total n=12814; observed n= 20 (0.2%); expected n= 118.9 (0.9%); RR=0.2 (95% CI=0.1,0.3), p<0.001. Pregnant, total n=5815; observed n= 19 (0.3%); expected n= 78.5 (1.3%), RR=0.2 (95% CI=0.1,0.4), p<0.001. Cohorts of children with SCD are indicated in the table. In summary, access to care, as well as acute anemias are a frequent cause of mortality. Along with viral pathogens and transfusion related deaths this indicates the importance of a safe blood supply. By adulthood, the observed frequency of individuals with SCD is only 1/5 of expected. However, reported clinic cohorts suggest similar if not better survival than in the general population, possibly due to lost to follow up, but also malaria/bacterial infection prevention and nutritional support. Careful prospective studies are needed.