Analytical Process Evaluation of Biochemistry Laboratory by Using Six Sigma Method

Abstract

Objectives: The primary purpose of medical laboratories is to provide the most accurate results appropriate to the patient's medical condition. Therefore, the reliability of each laboratory must be scientifically tested. Approximately 10% of laboratory errors occur in the analytical phase. In this study, we aimed to evaluate analytical process performances of 14 routinely assayed parameters according to six sigma methodology.

Materials and Methods: Mean, standard deviation and coefficient of variation were calculated from internal quality control data for three months from 14 routinely assayed parameters (albumin, alanine aminotransferase, aspartate aminotransferase, chloride, creatinine, glucose, HDL cholesterol, lactate dehydrogenase, potassium, total cholesterol, total protein, sodium, triglyceride and urea) in the laboratory (Roche Cobas c501). Bias was calculated using external quality control values for same months. Total error was also calculated. Acceptable total error was determined according to the Clinical Laboratory Improvement Amendments and Turkey criteria. Sigma values were calculated and divided into four groups; as <3 unacceptable; 3-4 suited for purpose; 4-6 acceptable; >6 world-class performance.

Results: According to the Clinical Laboratory Improvement Amendments and Turkey sigma assessment, first levels of chloride, total cholesterol, glucose and urea performance were unacceptable. Moreover according to the Clinical Laboratory Improvement Amendments  sigma assessment, first levels of albumin, creatinine, total protein; and both levels of sodium, chloride and urea were unacceptable. Other tests were found to be suited for purpose, acceptable or world-class performance.

Conclusions: Sigma measurements should be routinely performed in laboratories for evaluating the analytical period performance of the laboratory. That will increase its quality via regulatory preventive actions. Our study allowed us to see and improve our measurement quality by determining the three-month periodic performance of our laboratory tests.