Association of Central Obesity with Kidney Function in a Population of Patients with Obesity

Background: In the last decades, the prevalence of obesity has increased worldwide. Diabetes and hypertension are often observed in this population, eventually leading a group of patients to chronic kidney disease (CKD). However, other specific features such as age and central obesity may play a role as well. The present study attempted to investigate the effects of these factors on the development of CKD in a group of obese patients, regularly followed in an outpatient program. Methods: Two-hundred and two obese patients, ages from 17 to 67, were studied. The collected data consisted of previous history of arterial hypertension or use of medications, diabetes and eGFR according to CKD-EPI and Salazar-Corcoran equations. CKD was defined as eGFR (CKD-EPI) less than 60 ml/min/1.73m2 and/or urine albumin/creatinine ratio (ACR)≥30 mg/g (creatinine). Anthropometric measurements were performed for calculation of BMI, waist circumference, neck circumference, body shape index (BSI), Conicity index (CI) and Adiposity Index (AI). Statistical tests were Spearman correlations and Chi-square test. Data were given as mean ± SD or median (25%-75%). Relative risk (RR) was calculated (95% CI). The data were considered significant when P<0.05. Results: From the 202 patients, 38 were males, median age: 47 ys old (37-56.2), median BMI: 44.65 (40.27-50.02). The prevalence of CKD was 19.8% and the patients were stages G1 to G3b, in which 53.5% presented GFR (CKD-EPI)<60 mL/min/1.73m2, 67.5% had ACR≥30mg/g and 20% had both. Among all patients, the RR of CKD was 1.35(1.19-1.6, P<0.001) for age >47, 19.8 (3.63 – 113.3, P<0.0001) for hypertensive and 3.54 (1.89 – 6.70, P < 0.0001) for diabetics. Estimated GFR, calculated by both CKD-EPI and Salazar-Corcoran, was inversely correlated to BSI (R=-0.25, P<0.01; R=-0.27, P<0.001, respectively) and CI (R=-0.23, P<0.01; R=-0.17, P<0.05, respectively). Both BMI and AI were not significantly correlated with eGFR in both methods. Conclusion: Hypertension followed by diabetes are the major risk factors for CKD in the obese population studied. Moreover, the decrease of renal function is highly associated with the magnitude of central obesity, as measured by BSI and CI. These results strongly suggest the need to focus on anthropometric evaluations to address central obesity, specially in hypertensive and diabetic obese patients. Funding: Government Support – Non-U.S.