Background: Comparison of assay results is very important for having a comparable backup analyzer to provide a quality laboratory service without interruption. Even though, several factors affect assay results by different instruments, little or no data is available regarding assay results comparison between Cobas 6000 (c501) and Cobas integra 400 plus in the study area. Thus, the present study was aimed to compare assay results of two fully auto-mated clinical chemistry analyzers: Cobas 6000 (c501) and Cobas Integra 400 Plus at the National Clinical Chemistry Reference Laboratory of Ethiopian Public Health Institute, Addis Ababa, Ethiopia.
Methods: The assay results for the 20 selected clinical chemistry parameters were obtained from 52 randomly selected samples on Cobas 6000 (c501) and Cobas integra 400 plus. Statistical analysis was done using Med-Calc software. The 2019 CLIA proposed acceptance limits for proficiency testing were used to check bias or difference obtained from correlation and regression analysis.
Results: Assay results comparison revealed almost perfect data correlations among all selected clinical chemistry parameters: Albumin, ALP, ALT, Alpha-amylase (AMYL), AST, Direct bilirubin, Total bilirubin, Total cholesterol, Creatine kinase, Creatine kinase MB-subunit, Creatinine, GGT, Glucose, HDLC4, LDH, Phosphate, Total Protein, Triglycerides, Uric acid, and Urea, on both analyzers with coefficient of determination (R2) ranging from 98.9% to 99.99% and coefficient of correlation (r) ranging from 99.4% to 100%, depicting the precision and reliability of assay results, standardization, and system equivalency. Moreover, the calculated bias/difference is lower than both CLIA total allowable error and CLIA allowable error.
Conclusions: In summary, regression/correlation analysis and calculated bias or difference revealed almost equivalent data representation of both analyzers as per the CLIA standard, thus showing that both fully automated analyzers are standardized and properly calibrated to be used simultaneously and inter-changeably as the main and back up analyzers for selected clinical chemistry parameters analyzed at the clinical chemistry reference laboratory.