The Epidemiology and Economic Burden of Major External Structural Birth Defects in Kiambu County, Kenya

Abstract

Background: Major external structural birth defects are defined as developmental abnormalities of intrauterine origin that are present at or soon after birth detectable visually during physical examinations and have significant health impacts on the affected children, thus requiring medical and/or surgical interventions. These defects continue to occur globally, however, the greatest burden is shouldered by resource-constrained countries and associated with lifelong resourceintensive physical disabilities exerting enormous financial burden on individuals, and health care systems, nonetheless, they have been unappreciated as a public health priority in Kenya. Objectives: The broad objective of the study was to determine the epidemiology and economic burden of major external structural birth defects in Kiambu County, Kenya. The specific objectives comprised; (i) to estimate the prevalence of major external structural birth defects, (ii) to identify the risk factors for major external structural birth defects, and (iii) to conduct a cost analysis of outpatient services for major external structural birth defects in the county. Methods: The study was conducted in 15 hospitals (3 county referral hospitals, 10 sub-county hospitals, and 2 faith-based hospitals within the Kiambu County purposively selected. It is the second-most densely inhabited of the forty-seven counties with an estimated population of 2.4 million of the approximated 47.5 million national population. Approximately 2.2% of its population aged ≥5 years are living with lifelong disabilities associated with congenital anomalies. It is a regional leading commercial hub with agriculture (tea, coffee, and dairy farming) largely as its economic mainstay. The study used two study designs, namely, hospital-based cross-sectional, and hospital-based case-control. First, a retrospective review of all medical records was conducted between January 1st, 2014, and December 31st, 2018, in the 3-county, and 10 sub-county hospitals to estimate the prevalence of the defects. The study enumerated all the cases of birth defects (873) recorded in the medical records in the five years; however, a five-year prevalence numerator of 362 cases was considered following a predetermined inclusion criterion, whereas a five-year prevalence denominator of 299,854 cases of registered live births was obtained from the Birth Registrar. The prevalence estimates were calculated as the number of cases [numerator] divided by the number of live births [denominator]. Associated 95% binomial exact confidence intervals were also computed and expressed per 100000 live births. Secondly, a hospital-based case-control study was conducted in 3 county referral hospitals, 8 sub-county hospitals, and 2 faith-based hospitals to identify the risk factors for the defects. Face-to-face interviewer-structured xviii questionnaires were administered to 408 study participants [102 cases, and 306 controls] to gather information retrospectively on maternal exposure to environmental teratogens, multifactorial, and sociodemographic-environmental factors during the periconceptional period during their last pregnancies. Logistic regression analyses were conducted to estimate the effects of the predictors on the odds of major external structural birth defects. Lastly, a retrospective review of the outpatient registers for occupational therapy clinics and face-to-face inquiries from occupational therapists were conducted to estimate the unit economic costs of outpatient services for the defects. A one-year time-horizon [January 1st, 2018, to December 31st, 2018] was adopted using ingredient techniques to gather data on the cost drivers from health care providers’ perspectives in the county in four hospitals (3 county referral hospitals, and 1 faith-based hospital). The study determined 349 cases following a predetermined inclusion criterion to calculate the unit economic cost in U.S Dollars [$] as the average of the total economic costs divided by the number of cases. Results: The study showed a steady annual increase in the prevalence estimates of the six groups of major external structural birth defects ranging from 44.04 (95% CI: 27.92-66.07) and 205.28 (95% CI: 173.15-241.64) per 100000 live births between 2014 and 2018. Defects of the musculoskeletal system were observed as the most prevalent ranging from 22.98 [95% CI: 11.87- 40.13] to 116.9 [95% CI: 92.98-145.08] per 100000 live births between 2014 and 2018. The study further showed women who conceived when residing in Ruiru sub-county [adjusted odds ratio (aOR): 5.28; 95% CI: 1.68-16.58; P<0.01], and Kiambu sub-county [aOR: 0.27; 95% CI; 0.076- 0.95; P =0.04]; and preceding siblings with history of birth defects [aOR: 7.65; 95% CI; 1.46- 40.01; P =0.02] as the predictors of these defects. The unit economic cost of all the cases was estimated at $ 1,139.73; and $ 1,143.51 for neural tube defects, $ 1,143.05 for congenital talipes equinovarus, and $1,109.81 for congenital pes planus. Conclusion: This study pointed to an upward prevalence trend in the county between 2014 and 2018 with defects of the musculoskeletal and central nervous systems accounting for the greatest public health and economic burden respectively attributed to genetic and multifactorial factors. Thus, my priority recommendations include the establishment of hospital-based surveillance systems as well as further epidemiological and economic evaluation studies to understand the magnitude of the most prevalent major external structural birth defects in Kenya.