Performance Evaluation of the Afinion AS100 Analyzer for Its Use in the Albumin Creatinine Ratio Test

BACKGROUND: Early detection of moderately increased albuminuria using the albumin-creatinine ratio (ACR) test is very important for preventing renal insufficiency and cardiovascular disease in patients with diabetes. The purpose of this study was to analyse the clinical usefulness of the Afinion AS100 Analyzer (Alere Technologies AS, Norway) for determining the ACR by evaluating its precision and linearity and comparing it with another conventional device. METHODS: Urine samples of patients and quality control materials were used for evaluation. The Afinion AS100 was used to measure albumin and creatinine, and the ACR was automatically calculated. The Cobas Integra 800 (Roche Diagnostics, Germany) was used as a reference instrument for correlation analysis. In accordance with the Clinical and Laboratory Standards Institute guidelines, precision, linearity, and turnaround time were evaluated, and the Afinion AS100 was compared with another device. RESULTS: The total coefficients of variation of albumin and creatinine were 2.8% and 2.9% for high concentration and 2.9% and 2.5% for low concentration, respectively. Both albumin and creatinine showed coefficients of determination of 0.999 or higher in linearity. Correlation coefficients of albumin, creatinine, and ACR were higher than the Clinical and Laboratory Standards Institute recommended value of 0.975, suggesting a high correlation as well as showing significant correlation with a 24-hour urinary albumin level obtained using the Cobas Integra 800. Mean turnaround time was 5 minute 35 seconds. CONCLUSIONS: The albumin, creatinine, and ACR tests performed with the Afinion AS100 showed satisfactory performance in terms of precision and linearity and showed good correlation with the central laboratory instrument and a 24-hour urine albumin quantitative test using a conventional instrument.

Performance Evaluation of STRATUS CS200 for Cardiac Markers

The STRATUS CS200 (Siemens Healthcare Diagnostics Inc., USA) has recently been developed as an on-site diagnostic instrument for assaying several kinds of cardiac markers within a short duration. The precision, linearity, comparison, limit of quantification, and turnaround time (TAT) were evaluated for troponin I, creatine kinase-MB (CK-MB), N-terminal pro-brain natriuretic peptide (NT-proBNP), and myoglobin assays according to guidelines provided by the Clinical and Laboratory Standards Institute. The total coefficients of variation of the four items were between 1.90% and 4.25%. All markers showed a linearity that was ≥0.99, and the values were within the manufacturer's range. All items showed a close correlation with E170 (Roche Diagnostics, Germany). The limits of quantification for troponin I, CK-MB, myoglobin, and NT-proBNP were 0.03 ng/mL, 0.3 ng/mL, 1 ng/mL, and 15 pg/mL, respectively. The TAT was 14 minutes. The performance of the STRATUS CS200 for assaying cardiac markers was highly satisfactory in terms of the precision, linearity, limit of quantification, and TAT, and it showed a good correlation with the comparative method.

Annual Report on the External Quality Assessment Scheme for Routine Clinical Chemistry in Korea (2016)

In 2016, the clinical chemistry proficiency-testing program consisted of 21 programs, including the general chemistry program of the Korean Association of External Quality Assessment Service. The general chemistry program consisted of 28 test items and was conducted using two level control materials four times per year. Based on the information and results for each test item entered by each institution, statistical analysis data according to test method, instrument, and reagent were reported. The report comprised a general statistics report showing the characteristics of all participating institutions and a separate institutional report showing the evaluation data of individual institutions. The statistics included the number of participating institutions and the mean, standard deviation, coefficient of variation, median, minimum, and maximum values for each group. Each report was composed of a table, histogram, and Levey-Jennings chart showing the statistics for each test item. The results of each institution and the statistics for each classification are presented in the table showing the statistics, and a standard deviation index is presented together with a method classification and a classification by reagent companies. A total of 14 items, including albumin, were evaluated by more than 1,000 institutions. There was no significant difference in the distribution of the measurement methods compared with those used in the previous year. The coefficient of variation showed a tendency to increase as the concentration of the level control material decreased and as the number of participating institutions decreased for each test item. Most of them showed a coefficient of variation within 10%. These statistical data will be useful when interpreting the survey results from the institutions and selecting a test method.