The ratio of urine albumin to creatinine used in screening for albuminuria among the middle-aged and elderly at high-risk for diabetes in an urban community with casual and morning urine specimens / 中华全科医师杂志

ABSTRACT

Objective To compare the value of clinical application of the ratio of urine albumin to creatinine (ACR) in the community-dwelled middle-aged and elderly at high-risk for diabetes in screening for albuminuria with casual and morning urine specimens. Methods Totally, 443 middle-aged and elderly people (234 men and 209 women) at high-risk for diabetes, with an average age of (59±8) years, were recruited from Changfeng Community of Shanghai in screening for albuminuria with casual and morning urine specimens collected on the same day, as well as another two morning urine specimens collected at an interval of two weeks, for determination of urine ACR. Albuminuria was defined as ACR equal to or more than 30 mg (albumin)/g (creatinnine) in two or more of the three urine specimens collected. Results Overall prevalence of albuminuria was 6. 3% ( 28/443 ) in the middle-aged and elderly according to diagnostic standard mentioned above, significantly higher in casual urine specimens than in morning urine specimens (14. 9% vs. 5.9%, P <0. 05). Urine ACR of casual urine specimens was significantly higher than that of morning urine (7. 1 mg/g vs. 3. 2 mg/g, P<0. 001 ). There was no significant difference in sensitivity and positive predictive value (PPV) between casual and morning urine specimens in screening for albuminuria (96. 4% vs. 92. 9%, and 99.7% vs. 99. 5%, respectively, P >0. 05). Specificity and negative predictive value (NPV) of casual urine specimens was significantly lower than those of morning urine specimens (90.6% vs. 100.0%, and 40.9% vs. 100.0%, respectively, P<0.05). The optimal cut-off value of ACR by casual urine specimens was 40. 0 mg/g in screening for albuminuria, based on receiver operating characteristic (ROC) curve, with sensitivity of 96. 4%, specificity 95.2%, PPV 57.5% and NPV 99. 8%. The middle-aged and elderly with negative albuminuria in morning urine but positive in casual urine had more risk factors for cardiovascular and chronic kidney diseases than those with negative albuminuria in both morning and casual urine specimens. Conclusions Morning urine specimen is better than casual urine for albuminuria screening in the middle-aged and elderly people with risk factors for diabetes in urban community, but casual urine used in screening for albuminuria is very convenient for collection. It is suggested that urine ACR of 40. 0 mg/g be used as an optimal cut-off value for casual urine in albuminuria screening among them.