Evaluation of the performance of urine albumin, creatinine and albumin-creatinine ratio assay on two POCT analyzers relative to a central laboratory method

Background: The evaluation of microalbumin, creatinine and albumin-creatinine ratio is very important in patients with diabetes for the early detection of kidney disease and the identification of patients at risk for complications from diabetes or hypertension. Methods: A total of 88 spot urine samples previously analyzed using the Vitros 5,1 FS (creatinine) and Beckman Coulter Immage (microalbumin) located in the central laboratory and having microalbumin and creatinine values within the Afinion and DCA Vantage reportable ranges were run on 2 point of care ( POC) instruments (Siemens DCA Vantage and Axis-Shield Afinion). Results: The mean values for the DCA Vantage were: 42.6mg/l for albumin, 10.3mol/l for creatinine, and 5.4mg/mol for ACR. For the Afinion AS100, the mean values were: 48.5mg/l for albumin, 9.5mol/l for creatinine, and 6.7mg/mol for ACR. The mean values obtained for CL were: 40.8mg/l for albumin, 10.0mol/l for creatinine, and 5.4mg/mol for ACR. All POC analyzers showed good correlation to the central laboratory tests for microalbumin, creatinine and albumin creatinine ratio (ACR) for Afinion (R ²=0.954, 0.974, and 0.964, respectively) and DCA Vantage (R ²=0.989, 0.987, and 0.991, respectively). With the exception of the DCA Vantage ACR (p=0.53), the levels of microalbumin, creatinine and ACR obtained for the Afinion and DCA Vantage instruments as compared to the CL were statistically different (p<0.05). The inter and intraday imprecision for both POC instruments was <2.9% and total imprecision <8.7%. Conclusions: The 2 instruments evaluated in this study were in good agreement with the quantitative laboratory results and thus can be used for microalbumin, creatinine and ACR assays at the POC. However, facilities using Afinion will have to use different normal range for ACR.