Avaliação dos níveis séricos de ácido úrico como fator de risco para o declínio da taxa de filtração glomerular em pacientes com doença renal crônica

Abstract

Introduction: Chronic kidney disease (CKD) has become a worrisome public health problem worldwide due to its increasing incidence and prevalence as well as its impact on morbidity and mortality. Treatment of CKD is based on risk factor intervention. However, currently known factors and their approach are insufficient to stop the disease. For this reason, it is imperative to search for other factors associated with its pathogenesis. Hyperuricemia has been identified as a condition associated with CKD, but causal association between them has not yet been proved. Objectives: 1. To evaluate the impact of hyperuricemia on the incidence and progression of CKD through a systematic review of the literature; 2. To evaluate the impact of serum uric acid levels on the decline of the glomerular filtration rate (GFR) in a population of chronic renal patients. Methods: Initially a systematic review of the literature was carried out between January 2005 and December 2016. The combination of keywords "chronic renal insufficiency AND hyperuricemia AND uric acid" was used to search in the Lilacs and Pubmed databases. The articles’ abstracts were evaluated by two researchers according to established inclusion and exclusion criteria. Secondly, the electronic records of 788 patients of the CKD outpatient clinic of the Hiperdia Minas/Juiz de Fora Center were analyzed and the impact of uric acid levels on the progression of CKD was evaluated. Results: A total of 150 studies involving humans were found. Twenty two were eligible; 13 studies evaluated incidence and 11 evaluated progression of CKD (increase in creatinine, variation of glomerular filtration rate, initiation of renal replacement therapy); two of the articles evaluated both outcomes. All thirteen articles that assessed the association between hyperuricemia and incidence of CKD showed a positive association between both. A further meta-analysis of 190,718 individuals evaluated the impact of hyperuricemia on the incidence of CKD and found an independent causal relationship. Regarding the progression of CKD, longitudinal studies presented conflicting results; three randomized controlled trials compared a group treated with allopurinol and a control group, all with improvement of the renal outcomes within the treated group. The Hiperdia Center database analysis results showed that patients admitted with hyperuricemia, that is, uric acid higher than 6.8mg/dL, presented almost twice the risk (IRR = 1.91 95% CI: 1, 21-3.00, p = 0.005) of rapid progression of CKD (TFG> 5mL/min/year). In addition, for each 1 mg/dL increase in the uric acid levels baseline, there was an additional 48% annual risk of progression (IRR = 1.48 95% CI: 1.16-1.88, p = 0.001). Conclusion: The systematic review suggested that hyperuricemia is independently related to the incidence of CKD, however, its role in disease progression is still controversial. Among patients with CKD, increased serum uric acid levels were associated with an increased progression of chronic kidney disease.