Effects of hyperuricemia on incident renal replacement therapy and all-cause mortality among patients with chronic kidney disease stages 3-5: a retrospective cohort study

ABSTRACT BACKGROUND: Findings regarding the effects of hyperuricemia on renal function and mortality have been inconsistent. OBJECTIVES: To investigate the effects of hyperuricemia on incident renal replacement therapy and all-cause mortality among patients with chronic kidney disease (CKD). DESIGN AND SETTING: Retrospective cohort study conducted in a medical center in Taiwan. METHODS: Patients with CKD in stages 3-5, without histories of renal replacement therapy, were consecutively recruited from 2007 to 2013. Their medical history, laboratory and medication data were collected from hospital records. The mean uric acid level in the first year of follow-up was used for analyses. Hyperuricemia was defined as mean uric acid level ≥ 7.0 mg/dl in men or ≥ 6.0 mg/dl in women. The primary outcomes were incident renal replacement therapy and all-cause mortality, and these data were retrospectively collected from hospital records until the end of 2015. RESULTS: A total of 4,381 patients were analyzed (mean age 71.0 ± 14.8 years; males 62.7%), and the median follow-up period was 2.5 years. Patients with hyperuricemia were at increased risk of incident renal replacement therapy and all-cause mortality, especially those with CKD in stages 4 or 5. Compared with patients with CKD in stage 3 and normouricemia, patients with CKD in stages 4 or 5 presented significantly higher risk of all-cause mortality only if they had hyperuricemia. CONCLUSIONS: In patients with CKD in stages 3-5, hyperuricemia was associated with higher risk of incident renal replacement therapy and all-cause mortality. Whether treatment with uric acid-lowering drugs in these patients would improve their outcomes merits further investigation.

Hyperuricemia is associated with low cardiorespiratory fitness levels and excess weight in schoolchildren / Hiperuricemia está associada com baixos níveis de aptidão cardiorrespiratória e excesso de peso em escolares

Abstract Objective: To evaluate the possible association between hyperuricemia and cardiorespiratory fitness levels/nutritional profile, grouped into a single variable, in schoolchildren. Method: Cross-sectional study of 2335 students from Elementary schools, aged 7-17 years of both genders, stratified by conglomerates of a municipality in Southern Brazil. Body mass index (BMI) was calculated and cardiorespiratory fitness (CRF) was assessed by the 6-minute run/walk test. The BMI and CRF were grouped into a single variable, considering: (1) low and normal weight/fit; (2) low and normal weight/unfit; (3) overweight-obesity/fit; (4) overweight-obesity/unfit. The Poisson regression (prevalence ratio, PR) was used for the association between hyperuricemia and BMI/CRF ratio with 95% confidence intervals and differences were considered significant when p < 0.05. Results: There is an association, although subtle, between the presence of hyperuricemia with low levels of CRF and the presence of excess weight, when grouped into a single variable. Boys and girls with this condition have higher prevalence of hyperuricemia (PR: 1.07; p = 0.007 for boys; PR: 1.10; p < 0.001 for girls). Conclusion: Together, excess weight and low levels of cardiorespiratory fitness are associated with the presence of hyperuricemia in schoolchildren.

Resumo Objetivo: Avaliar a possível relação entre hiperuricemia com aptidão cardiorrespiratória e o estado nutricional, agrupados, em escolares. Método: Estudo transversal com 2.335 escolares da educação básica de 7 a 17 anos, de ambos os sexos, estratificados por conglomerados de um munícipio do sul do Brasil. Foi calculado o índice de massa corporal (IMC) e a aptidão cardiorrespiratória (APCR) foi avaliada pelo teste de corrida/caminhada de 6 minutos. O IMC e a APCR foram agrupados em uma única variável, considerando: 1) baixo peso-normal/apto; 2) baixo peso-normal/inapto; 3) sobrepeso-obesidade/apto; 4) sobrepeso-obesidade/inapto. A regressão de Poisson (razão de prevalência; RP) foi usada para associação entre hiperuricemia e a relação APCR/IMC com intervalos de confiança de 95% e diferenças significativas consideradas para p < 0,05. Resultados: Observa-se associação, embora sutil, entre a presença de hiperuricemia com baixos níveis de APCR e a presença de excesso de peso, de forma agrupada. Meninos e meninas, com essa condição, têm maior prevalência de hiperuricemia (RP: 1,07; p = 0,007; RP: 1,10; p < 0,001, respectivamente), em comparação com seus pares com bons níveis de APCR e estado nutricional adequado. Conclusão: De forma conjunta, o excesso de peso e os baixos níveis de aptidão cardiorrespiratória estão associados com a presença de hiperuricemia em escolares.

Hypouricemic and antioxidant activities of Allium cepa Lilliaceae and quercetin in normal and hyperuricemic rats

To evaluate the hypouricemic and antioxidant effects of Allium cepa Lilliaceae [Allium cepa L.] and quercetin in normal and hyperuricemic rats. The following study was conducted in the Department of Nutrition and Biochemistry, Tehran University of Medical Science, Iran, between May 2007 and March 2008. A total of 48 male Wistar rats [body weights: 180-200 g] were randomly divided into 8 equal groups including normal; normal + Allium cepa L. [5g/kg]; normal + quercetin [5mg/kg]; normal + allopurinol [5mg/kg]; hyperuricemic; hyperuricemic + Allium cepa L. [5g/kg]; hyperuricemic + quercetin [5mg/kg]; hyperuricemic + allopurinol [5mg/kg] once a day for 14 days. Experimentally, hyperuricemia in rats was induced by intraperitoneal injection of potassium oxonate [250mg/kg]. Allium cepa L. and quercetin treatments for 14 days significantly reduced [p=0.000] the serum uric acid levels of hyperuricemic rats in a time-dependent manner. All treatments significantly inhibited hepatic xanthine oxidase/xanthine dehydrogenase activity. Allium cepa L. and quercetin treatments led also to a significant improvement in biomarkers of oxidative stress in hyperuricemic rats [p=0.000]. Although the hypouricemic effect of allopurinol was much higher than that of Allium cepa L. and quercetin, it could not significantly change oxidative stress biomarkers. These results may be responsible partly for the beneficial effects of Allium cepa L. and its major flavonoid on hyperuricemia and oxidative stress