A Spatial Analysis of Hypertension Prevalence in Rural and Urban Malawi

BackgroundNon-communicable diseases (NCD) represent a large and rapidly growing disease burden in Malawi and the wider sub-Saharan Africa region. National and regional NCD prevalence estimates and mapping, establishment of associated risk factors, and trend monitoring are vital for sustaining hard-won gains in well-being and life expectancy from the successful management of infectious diseases. MethodsBetween 2012 and 2016, blood pressure was measured in a population-representative sample of 29,628 Malawian adults (18+ years) residing in two locations; the southern part of rural Karonga district and urban Area 25 in Lilongwe city. Each location was divided into approximately 200 zones with individuals assigned the zone in which their home was located. A conditional autoregressive (CAR) model was fitted to estimate zonal hypertension prevalence. Estimates were plotted on regional maps featuring key amenities, healthcare facilities, and transport links. Individual-level economic and lifestyle covariates were then incorporated to assess how much of the variation could be explained by those covariates. ResultsVariation in hypertension prevalence was observed in both the rural and urban location (P < 0.0005), with high-prevalence zones clustering in areas near to major transport links and/or concentrations of amenities. Covariates explained most of the variation in both sites (P > 0.14). ConclusionsIn rural and urban Malawi, hypertension prevalence is higher among those of relatively high wealth, those who are closer to local amenities, or a combination of these two factors. More detailed data are needed to determine if these associations are explained by wealth-consequent behaviours such as sedentary occupations and deleterious lifestyle choices.