Decreased renal function and associated factors in cities, towns and rural areas of Tanzania: a community-based population survey

OBJECTIVES: Data on renal dysfunction in sub-Saharan Africa, comparing urban and rural areas, have not yet been reported. Therefore, we aimed to determine the distribution of low estimated glomerular filtration rates (eGFRs) in urban and rural Tanzania, to describe factors associated with low eGFR and to quantify fractions attributable to common risk factors. METHODS: We conducted a community-based survey of 1095 randomly selected Tanzanian adults (≥18 years). A structured questionnaire and examinations were used to document sociodemographic characteristics, diet, physical activity, anthropomorphic measurements and blood pressure. Blood tests were performed for HIV infection, diabetes mellitus and creatinine. eGFR was calculated using two equations recommended for African adults. RESULTS: Serum creatinine was available for 1043 participants: 170 in Mwanza city, 326 in district towns and 547 in rural areas. Mean age was 35.5 years and 54% were females. The prevalence of eGFR < 60 ml/min/1.73 m(2) in these 3 strata was 2.3% (95% CI = 0.8-6.6%), 7.5% (4.7-11.8%) and 7.4% (5.1-10.6%), respectively. When age standardised to the WHO world population, prevalences were 3.8%, 10.1% and 8.1%. Factors associated with low eGFR included district town residence, older age, greater wealth, less physical activity and hypertension. Only 21% of cases with eGFR < 60 ml/min/1.73 m(2) were attributable to HIV, hypertension or diabetes. CONCLUSIONS: Decreased renal function is common in Tanzania, particularly in district towns, and unique risk factors for kidney disease may exist in this population. Population-specific strategies for prevention, early diagnosis and treatment of kidney disease are needed for Africa.