Influência dos fatores de risco tradicionais e não-tradicionais na prevalência da doença renal do diabetes no diabetes tipo 1

Abstract

This dissertation analyses the association between the presence of chronic kidney disease (CKD) and elevated serum uric acid levels, self-reported color race, and genomic ancestry in patients with type 1 diabetes. This dissertation includes two articles, both analyzing data from multicenter, cross-sectional studies, with patients from all geographic areas of Brazil, that initially included 1760 patients. The studies used questionnaires to collect clinical data of the patients, as well as a clinical examination with the evaluation of anthropometric data and laboratory tests. Renal function was estimated by the CKD-EPI formula in adults and was expressed as the glomerular filtration rate (GFR). Albuminuria concentration was measured from a morning urine sample. The presence of albuminuria was defined as albuminuria &#8805; 30mg/dl. The studies divided the patients into two groups: Normal renal function group (GFR &#8805; 60 ml/min and the absence of albuminuria) and the CKD group (GFR <60ml/min and/or the presence of albuminuria). The second study classified patients according to self-reported color race and used autosomal Ancestry Informative Markers (AIMs) to infer the genomic ancestry (GA). The GA was expressed as percentages, with the sum of European, African and Native Amerindians equaling 100%. In the first study, the multivariate analysis revealed an association between higher levels of uric acid and lower GFR, even in patients in the normal renal function group. Every 1mg/dl increase in the levels of serum uric acid was associated with a decrease in 4.11ml/min in the GFR. The second study revealed that more patients self-reported themselves as Black and Brown in the CKD group than in the normal renal function group. However, self-reported color-race was not associated with CKD in the multivariate analysis. The binary logistic regression used to evaluate the relationship between African GA and renal function showed a significant association between a higher African ancestry and CKD. However, a multivariate logistic regression between African GA and CKD, after the adjustment for confounding factors, did not confirm this association. The conclusion of the first study is that higher levels of serum uric acid were associated with a lower GFR, even in patients from the normal function group. The second study concluded that self-reported color race or a higher African GA were not associated with CKD after adjustments. This can possibly be explained, at least in part, by the low percentage of African ancestry that the study encountered, indicating that our population is extremely admixed and should be compared to other populations with caution. Further studies should be conducted to better evaluate the relationship between new risk factors and even between known risk factors associated with diabetic kidney disease since it is a complication associated with an elevated morbi-mortality, high cardiovascular risk, and an excessive burden to the health care system.