| Background and aimsMicroalbuminuria (MA) is an independent risk factor for cardiovascular diseases, renal outcome, as well as all-cause mortality. So it is very important to screen for MA for individuals at increased risk for chronic kidney disease (CKD) and cardiovascular diseae(CVD). Albumin creatinine ratio(ACR) in a first-void morning urine sample, as a simple and comparably accurate way for detecting MA, is widely recommended. There is world-wide acceptted cutoff of urinary albumin excretion(UAE) for defining MA, whereas the cutoff of ACR for MA varies among guidelines and has not yet been well-established in Chinese. Hence, well-designed study is sorely needed for determining the cutoff of ACR for Chinese. In addition, improvement in MA was found to be associated with better outcomes of CAD and CKD, so it is essential to find out the potential risk factors for MA. Obesity, as a risk factor for MA, can be estimated by different anthropometric parameters. But it remains elusive which of them is best for predicting MA. Up to now there is no report about the relationship between anthropometric parameters and MA in China. On the other hand, hyperuricemia, as the relative factor for MA, seemed to result in more CKD in female than male, but the opposite effects on CKD was reported in China, so further research is necessary. Because urinary creatinine in ACR is the confounding factor, UAE is the better method for detecting albuminuria in the research of relative factors for MA, which is rare used because of the inconvenient collection. We used eight-hour overnight UAE as the standard assessment of albuminuria, and assess to investigate the accuracy of urinary albumin measurements for detecting MA, the Chinese gender-specific discriminator value of ACR for MA, and the UAE associated relative factors in Chinese general population.MethodsThe epidemiological study regarding relationship between metabolic syndrome and chronic kidney disease in Pinggu district, Beijing has been performeded in our research. The investigated subpopulation devoid of known renal disease was analyzed. Another 59 participants were student volunteers, aged 20 to 29 years. The participants completed a standardized interview including a medical questionnaire, a physical examination, collection of the first morning urine and 8-hour overnight urine sample, and a series of laboratory tests (e.g. kidney function, lipid, glucose, serum uric acid, hypersensitive C-reactive protein, urinary albumin and creatinine). Eight-hour overnight UAE was referred as the standard assessment for albuminuria. Receiver Operating Characteristic Curve (ROC) analysis was used to determine the ACR cut-off value for microalbuminuria. The multiple linear regression and Logistic regression analyzed the relative factors of UAE. Spss (version 18.0)and Medcalc (version 11.1.1.0) were used for the analysis.Results1?A total of 1056 study participants (494 males and 562 females,50.2±12.1 years of age)were enrolled.2?(1)The ACR of the overnight urine and first-void morning urine had the best correlation(r=0.918, P< 0.001) compared with UAC (z=23.7,P<0.001); (2) ACR in first morning void urine also had the better correlation with 8h-UAE(r=0.662, P=0.000; z=2.68, P=0.007). (3) According to ROC curve analyses, the overnight-urine ACR, as a measure to define albuminuria, was better than ACR and UAC of the morning urine and overnight-urine UAC. There was no significant difference among ACR and UAC of the morning urine.3?(1)The discriminator value of ACR for microalbuminuria by ROC curve analysis was 1.95mg/mmol (sensitivity 97.6% and specificity 88.6%) for men,3.62mg/mmol (sensitivity 83.8% and specificity 89.1%) for women and 2.78mg/mmol (sensitivity 88.7% and specificity 85.9%) for overall. (2)The upper boundary of microalbuminuria by ROC curve analysis was 22.59mg/mmol (sensitivity 100% and specificity 98.8%). (3) According to the inter-rater agreement analysis, the gender-specific discriminator values for ACR derived from the present study had a sensitivity of 91.3% and a specificity of 88.2%. And its positive and negative likelihood ratios were respectively 7.56 and 0.1, and its positive and negative predictive values were respectively 56.9% and 98.4%.4?The AUC estimates for the prediction of abnormal UAE by five Anthropometric indicators performed no significant difference. The multiple linear analysis showed body mass index (BMI) was significantly related to 1gUAE in overall and females, but showed no relationship in males.5?In multiple logistic regression, male, hypertension, diabetes, hyperuricemia and elevated hsCRP were significantly associated with albuminuria. If stratified by gender, the associations of albuminuria with diabetes, hyperuricemia and elevated hsCRP remained significant in females, whereas in males only that of albuminuria with hypertension and diabetes persisted significantly. (serum uric acid OR=8.997,95%CI=2.640-30.668,P<0.001; HsCRP OR=2.570,95%CI=1.258-5.250, P=0.010).Conclusions1. The timed urine and ACR had better accuracy compared with random urine and UAC when detecting MA.2?The genetic-specific ACR discriminator value for determining microalbuminuria in Han Chinese was 1.95mg/mmol for male and 3.62mg/mmol for female.3?Five anthropometric indicators performed no significant difference in predicting abnormal UAE, and had significant relationship wirth UAE especially in females.4?The potential risk factors of UAE included male, hypertension, diabetes, hyperuricemia and elevated HsCRP, but hyperuricemia and elevated HsCRP had the genetic-specific effect on UAE, especially in females. |
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