Temporal relation between body mass index and renal function in individuals with hypertension and excess body weight.

Objective: Recent evidence has suggested obesity as an independent risk factor for chronic kidney disease. However, the temporal relation between body mass index (BMI) and early renal dysfunction is unknown. This study aimed at evaluating whether longitudinal variations in BMI would reflect on changes in estimated glomerular filtration rate (GFR) in hypertensive individuals with excess body weight.

Methods: This was a cross-sectional, longitudinal study.

Results: Of the 218 participants who attended the first examination, 150 were available for paired final analyses. At the end of follow-up, GFR decreased by 1.024 mL/min for each 1-kg/m(2) increment in BMI (P<0.03). When BMI was analyzed in quartiles, a positive graded relation with GFR changes was observed in quartiles 1 and 2 (individuals who maintained or lost weight), and a negative relation in quartiles 3 and 4 (individuals who gained weight, P=0.05). A significant difference was observed between the smallest and highest BMI quartiles (P=0.01). At the end of follow-up, the 76 participants (51%) who gained weight (+4.6+/-0.4 kg) showed a reduction in GFR (-2.99+/-1.99 mL/min) of borderline significance (P=0.06) and a significant increase in fasting plasma glucose and triacylglycerol levels. Conversely, the 74 participants who maintained or lost weight showed no significant change in GFR and in fasting plasma glucose and triacylglycerol levels, although their blood pressure decreased significantly.

Conclusions: Our study showed a significant temporal association between changes in BMI and GFR in overweight and obese hypertensive patients.