Assessment of Preanalytical Errors by Six Sigma Method and Pareto‘s Principle

Aim: In this study, we aimed to evaluate the preanalytical errors over a five year period using the Six Sigma methodology and Pareto Principle in the clinical biochemistry laboratory. Methods: Five-year sample rejection data between January 2015 and December 2019 in the clinical biochemistry laboratory were analyzed and classified according to the reasons for rejection. Six Sigma levels for the total and each preanalytical error were calculated with Westgard online formula. Preanalytical errors were evaluated according to their frequencies ranks and percentages with Pareto's principle. Results: The overall rate of five-year total critical preanalytical errors was 1.91% and the sigma level was 3.6. According to Pareto's chart, the three most common errors among the five-year preanalytical rejections were clotted sample (42.49%, sigma value:4), insufficient sample (23.53%, sigma value:4.2), and wrong container (8.01%, sigma value:4.5). Conclusion: Six Sigma is a quality management methodology used to evaluate laboratory performance processes according to universal quality criteria. Calculated sigma values of preanalytical errors in our laboratory were within the acceptable range. However, planned regulatory activities for frequently observed preanalytical errors should be a laboratory management strategy to reduce these error rates and improve our laboratory performance.