Mortality in Sickle Cell Anemia in Africa: A Prospective Cohort Study in Tanzania

Abstract

BackgroundThe World Health Organization has declared Sickle Cell Anemia (SCA) a public health priority. There are 300,000 births/year, over 75% in Africa, with estimates suggesting that 6 million Africans will be living with SCA if average survival reaches half the African norm. Countries such as United States of America and United Kingdom have reduced SCA mortality from 3 to 0.13 per 100 person years of observation (PYO), with interventions such as newborn screening, prevention of infections and comprehensive care, but implementation of interventions in African countries has been hindered by lack of locally appropriate information. The objective of this study was to determine the incidence and factors associated with death from SCA in Dar-es-Salaam.Methods and FindingsA hospital-based cohort study was conducted, with prospective surveillance of 1,725 SCA patients recruited from 2004 to 2009, with 209 (12%) lost to follow up, while 86 died. The mortality rate was 1.9 (95%CI 1.5, 2.9) per 100 PYO, highest under 5-years old [7.3 (4.8–11.0)], adjusting for dates of birth and study enrollment. Independent risk factors, at enrollment to the cohort, predicting death were low hemoglobin (<5 g/dL) [3.8 (1.8–8.2); p = 0.001] and high total bilirubin (≥102 µmol/L) [1.7 (1.0–2.9); p = 0.044] as determined by logistic regression.ConclusionsMortality in SCA in Africa is high, with the most vulnerable period being under 5-years old. This is most likely an underestimate, as this was a hospital cohort and may not have captured SCA individuals with severe disease who died in early childhood, those with mild disease who are undiagnosed or do not utilize services at health facilities. Prompt and effective treatment for anemia in SCA is recommended as it is likely to improve survival. Further research is required to determine the etiology, pathophysiology and the most appropriate strategies for management of anemia in SCA.

The burden of sickle cell disease in Cape Town

“…A retrospective cross-sectional hospital-based study may miss children with severe disease who have died in early childhood, and there may be individuals who have a mild disease phenotype and are never diagnosed. 18 In addition some patients may have died in secondary hospitals, though we are not aware of any such cases.…”

Nutritional status, hospitalization and mortality among patients with sickle cell anemia in Tanzania

“…The incidence rate of death was 2.5 per 100 person years observation (PYO) (95%CI 1.9-3.3), similar to the full cohort at 2.0 per 100 PYO. 19 Controlling for age at enrolment, and stratified by age group, there was no evidence of an association between nutritional status at enrolment and risk of mortality, for example: BMIinternal z-score (BMIiZ score) hazard ratio [ …”

“…It is possible that an effect of malnutrition on mortality in our SCA population is limited to young children who have the highest mortality among SCA patients, due particularly to infections, 25,[33][34][35] including in our cohort. 19 Malnutrition may have the greatest effect on mortality when mediated through an interaction with infections, as suggested in a Kenyan study in which the majority of deaths in young children attributable to malnutrition were ascribed to infection as the immediate cause of death. 36 In the absence of newborn screening, this survivor cohort, with a small number of patients in the youngest, most vulnerable age group, may have resulted in a lack of power to detect a true association.…”

“…Unfortunately, the cause of death remains unknown for the majority of cases in our cohort, due to the high number of deaths that occurred in the home. 19 …”

Morbidity and Mortality in Anemia

“…One review reported 42% reduction in mortality in SCA in USA, 0 to 3 years old, between two eras, 1995-1998 and 1999-2002 (71). There is compelling justification for implementation of these interventions in Africa to prevent deaths due to infections (65,66). Sudden death is not uncommon among SCA patients.…”