The prevalence of sickle cell trait among adolescents in Bungoma County, Kenya.

Abstract

Background: Sickle cell disease (SCD) is a genetic disorder inherited in autosomal recessive fashion and affects the haemoglobin (Hb) molecule. The homozygous state (HbSS) is the severest form of SCD and the heterozygous state(HbAS) is the Sickle cell trait or carrier state (SCT). Health education, genetic counseling, testing and identifying persons with the sickle cell gene and advising them on how to prevent birth of children with SCD are important primary intervention strategies for control of SCD. Objectives: To determine the prevalence of sickle cell trait among adolescents attending mixed day secondary schools in Bungoma County. To determine the haemoglobin variants among adolescents attending mixed day secondary schools in Bungoma County. To test the association between the demographic characteristics and sickle cell trait among adolescents attending mixed day secondary schools in Bungoma County. Methods cross-sectional study was done on adolescents attending mixed day secondary schools in Bungoma County of Western Kenya between January 2017 and July 2017. Stratified random sampling was applied; the county was stratified into 9 constituencies; a mixed day secondary school was selected randomly from each constituency. Public health education on SCD control was offered to 2389 students in 9 schools, 2248 met eligibility criteria. A total of 225 eligible participants were selected randomly from the school registers and consented. Pretest counseling was done followed by testing for sickle cell gene status using a point of care (POC) device (The Sickle scan™). Post test counseling was offered. Demographics and test results were documented. Proportions and Percentages was used to describe categorical data; Mean and Median for continuous data. Logistic regression was done and risk ratios (RR) generated, Pearson chi square was used to test for associations. Level of significance was set at p-value <0.05 with Confidence interval at 95%. Results: All 225 participants consented for testing; Males: 116/225(51.6%), Females: 109/225(48.4%). The median age was 17 years. HbAS prevalence was 18.7% (42/225) (CI 0.14-0.24). Proportion of males with HbAS was 24/116(20.7%); proportion of females with HbAS was 18/109(16.5%). Proportion of HbAS among students with known family history of SCD was 6/12 (50%);proportion of HbAS among those with no known family history of SCD was 36/213 (16.9%).Of those with family history of SCD; 1/12(8.3%)reported a sibling,9/12(75%) reported a cousin and 2/12(16.6%)reported other relatives. Hb variants were HbAA (183/225,81.3%) and HbAS (42/225,18.7%), there were no other Hb variants. There was no invalid result. Those with Family History of SCD were three times more likely to have HbAS(RR- 2.958, p-value= 0.004,CI:1.561-5.607). Conclusion: Prevalence of HbAS among adolescents is high. Hb variants found were HbAA and HbAS, there was no HbSS or HbC variants found. Having a Known Family History of SCD was significantly associated with having HbAS. Recommendations: Public Health Education on SCD and SCT to Bungoma County residents. Setting up of genetic counseling and testing centers for SCD and SCT in Bungoma County.