Introduction
Sickle cell disease (SCD), an autosomal recessive disorder of the red blood cell, is the commonest monogenic disease with more than 300,000 affected births annually worldwide, mostly in low and middle-income countries.1,2 The deformed red cells in SCD lead to recurrent acute vaso - occlusive episodes, hemolysis, anemia, organ damage resulting in impaired quality of life, and premature mortality.3 SCD was first described in India in 1952 among the Toda and Irula tribes living in the mountainous regions to the southeast of the Gudalur Valley in the Nilgiri Hills of Tamil Nadu, in southern India. 4 The βs gene is now known to be widespread among the aboriginal population of the Deccan plateau of Central India, Orissa, Wayanad district of Kerala with a frequency between 5% to 31%.5  Piels et al estimated that, in 2010, three countries, India, Nigeria, and the Democratic Republic of the Congo accounted for more than half the births with this disease globally.1 In India, the aboriginal or scheduled tribes (ST) populations form 8.6% of the total population constituting 104 million individuals.6 It is estimated that in 2010 approximately 44,400 babies with SCD were born in India,1 which is more than 20 times the number born in the US.7
While SCD is associated with loss of approximately 22 years of life expectancy, this is likely to be impacted by genetic, environmental, socioeconomic factors.8 A previous study from the State of Orissa,9 had suggested that the clinical phenotype of SCD observed in the aboriginal population may be milder. A study from the neighboring District of Wayanad in Kerala stated that they survive longer than individuals of African or Caribbean descent. However, this latter observation may be erroneous, being based on a relatively small cross-sectional study.10 As there is limited literature on the mortality rate of SCD in the aboriginal population, we undertook a retrospective cohort study to determine the rates and causes of mortality due to SCD in this community.