Introduction: Rheumatic heart disease (RHD) remains a leading cause of cardiovascular mortality in sub-Saharan Africa. Identifying geographic “hot spots” and high risk populations are crucial for the development of RHD prevention and screening strategies in high burden areas.
Objectives: We aimed to identify demographic patterns and geographic variation in RHD prevalence in western Kenya.
Methods: We conducted a retrospective chart review of all patients <50 years old (n=937) attending adult cardiology clinic at a national referral hospital in western Kenya. Demographic information, residential location and cardiac history were collected. We mapped the spatial distribution of cardiac disease rates and analyzed the effect of distance from the hospital on RHD status using multivariable logistic regression.
Results: Two-thirds (64%) of all patients <50 years old had RHD. RHD patients were younger (26 vs. 33 years, p<0.001) and more often female (69% vs. 59%, p=0.002) than non-RHD patients. Patients of Nilote ethnicity had over twice the odds of RHD than non-Nilotes (OR 2.5, 95%CI 1.7-3.7). Global clustering of disease rates exists within 200km of the hospital with significant clustering of the RHD and non-RHD rate difference seen surrounding the hospital in the (Moran’s I: 0.3, p=0.001) (Figure). Clustering was attenuated after controlling for age, gender, ethnicity and distance from the hospital. There was an interaction between ethnicity and distance to the hospital such that the odds of RHD increased with further distance for Nilotes, but the odds of RHD in non-Nilotes decreased with further distance.
Conclusion: Most adult cardiology patients treated at a national referral hospital in western Kenya have RHD. Young females of Nilote ethnicity are commonly affected. Ethnicity and distance to the hospital interdependently affect the odds of RHD, and geographic clustering of disease rates may reflect this relationship. Future studies in this area should consider the impact of ethnic predisposition to RHD.