The prevalence and clinical correlates of atrial fibrillation in those aged 70 and over in the Hai district of northern Tanzania

Abstract

Background The elderly population in sub-Saharan Africa (SSA) is increasing rapidly, with a consequent rise in noncommunicable disease (NCD). The prevalence of stroke disease is already known to be higher in SSA than in highincome countries (HICs). There are currently no communitybased data on the prevalence of atrial fibrillation (AF) or hypertension (HTN) specifically in elderly SSAs. Design Cross-sectional community-based observational study, with case-control sub-group analysis. Methods Approximately one quarter of the population (n=2232) aged 70 and over of a demographic surveillance site in the rural Hai district of Northern Tanzania underwent screening for AF by 12-lead electrocardiography (ECG), in addition to a subgroup undergoing ambulatory cardiac monitoring looking for paroxysmal AF (n=232). Demographic data were also collected along with disability level, body mass index and blood pressure (BP). The gender-specific prevalence of AF, paroxysmal AF and hypertension in each 5-year age band was determined. ECGs were examined digitally, and P wave indices in this population were described. Results There were only 15/2232 (12 female) participants with AF, giving an age-adjusted prevalence of 0.64%. 6/233 (2.6%) had at least 1 paroxysm of AF, suggesting a total overall prevalence of AF as high as 3.2%.1553/2232 had a BP ≥140/90, giving an age-adjusted prevalence of hypertension of 69.7%. Women had a higher mean systolic (166.0 vs. 154.3mmHg) and diastolic (89.3 vs. 83.1mmHg) BP. Conclusions The prevalence of AF is much lower in this population than elsewhere in the world and points towards potential protective genetic and environmental factors and some differences in risk factor profile. However, the low prevalence of AF is particularly interesting in the setting of a prevalence of hypertension and stroke that is similar to African- Americans in HICs.