Bioelectrical impedance outperforms waist circumference for predicting cardiometabolic risk in Congolese hypertensive subjects: a cross-sectional study

BACKGROUND Waist circumference threshold values used in sub-Saharan Africa correspond to those of European populations and are therefore inappropriate. Thus, they may over predict insulin resistance, especially in hypertensive Africans, in whom there is often no association between blood pressure and insulin resistance. Using bioelectrical impedance measurement in sub-Saharan Africa could possibly be advantageous to overcome the shortcomings of waist circumference measurement. The aim of this study was to evaluate the contribution of body composition estimation by bioelectrical impedance to predict cardiometabolic risk in Congolese hypertensive subjects. METHODS Cardiovascular profiling and body composition analysis by bioelectrical impedance was measured in 400 patients (men = 40%; age = 51.1 ± 12.6 years). Patients were diagnosed with a metabolic syndrome (MS) according to the IDF Criteria with and without the "blood pressure" criterion to remove any confounding autocorrelation bias, a visceral fat-MS (with and without the "blood pressure" criterion) being defined by the presence of ≥ 2 criteria with the precondition of excess visceral fat defined by a bio impedance measurement score >10/30. Total cardiovascular risk was assessed using the criteria of Framingham-2008. RESULTS The frequencies of enlarged waist circumference (71.9% vs 68.9%, p = 0.52) and IDF-MS without blood pressure criterion (24.9% vs 21.9%, p = 0.48) were similar among hypertensive vs. non hypertensive however excess visceral fat (57.6% vs 33.8%, p <0.0001) as well as visceral fat-MS without blood pressure criterion (18.9% vs 11.3%, p = 0.04) were more prevalent among hypertensive. Finally, total cardiovascular risk as well as arterial hypertension risk were associated with visceral fat, but not with waist circumference (p > 0.05). CONCLUSIONS Pending the determination of thresholds values for pathological waist circumference adapted to sub-Saharan populations, using bioelectrical impedance measurement may contribute to better characterize the cardiometabolic risk and the insulin resistant phenotype of hypertensive sub-Saharan Africans.