Associação entre índices de adiposidade e marcadores de doença renal

Abstract

Background: obesity is a global public health problem and an important risk factor for chronic kidney disease (CKD). However, the role of adiposity indices in discriminating CKD and predicting renal function has not yet been fully elucidated, considering different anthropometric measurements. Furthermore, abdominal adiposity indices better reflect the centralization of obesity and are more directly able to assess metabolic deterioration, which can affect markers of kidney disease, such as albuminuria and estimated glomerular filtration rate (eGFR). The objective of this Thesis was to evaluate the discriminatory performance of adiposity indices for the diagnosis of CKD and its association with markers of kidney disease. Materials and Methods: this Thesis consists of a transversal and a longitudinal design. The first of them used laboratory data from the National Health Survey (PNS) 2013 to evaluate the discriminatory performance of adiposity indices for CKD in a sample of 8,426 adult individuals. The second design used data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brazil) cohort to evaluate the association between adiposity indices with incident albuminuria and kidney disease progression. This cohort has around 15 thousand adult individuals at baseline. In this analysis, adjustments were made for potentially confounding variables. Results: when analyzing PNS data, it was found that adiposity indices ─ body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR) and body shape index (ABSI) ─ were able to discriminate CKD in the total sample and when stratified by sex and age group, with WHR having a better performance in relation to the area under the ROC curve (AUC) in all analyzes (0.653 in the total sample, 0.663 in males, 0.649 in male female, 0.606 in adults and 0.549 in the elderly). In the ELSA-Brazil cohort, it was found that incident albuminuria was present in 350 (2.82%) of the individuals. Adiposity indices (BMI, WC, WHtR and waist-hip ratio ─ WHR) were directly associated with albuminuria, these associations remained significant even after adjustments for potentially confounding covariates. These same adiposity indices showed a significant association predicting the kidney disease progression, but there was no interaction with time since the first visit. After adjustments for confounding covariates, only BMI and WC were predictors of the kidney disease progression. Conclusion: adiposity indices showed relative discriminatory power for CKD, but WHtR showed better discriminatory power. The increase in adiposity index values was associated with an increase in the probability of incident albuminuria and correlated with kidney disease progression. Public health actions aimed at controlling overweight and obesity are important and should be recommended, since the increase in adiposity indices are associated with the kidney disease markers studied.