title: Application of sigma metrics for the assessment of quality assurance using the MQ-2000 PT HbA1c analyzer.
abstract: BACKGROUND
  Glycosylated hemoglobin (HbA1c) concentrations measured in clinical chemistry laboratories show large differences between their interlaboratory reported values. Laboratory measurements of quality performance should be based on quantitative data. The sigma metrics model provides an objective method for the assessment of current HbA1c assays and is useful in quality management planning. The aim of our study was to evaluate the analytical performance of the MQ-2000 PT HbA1c analyzer test results in the context of our operating conditions on the sigma scale.
  
  
  METHODS
  The coefficient of variation was determined from the calculated mean and standard deviation evaluated from internal quality control (QC) (N=168 days) (Shanghai Huachen Biological Reagent Co. Ltd, China) data, and records of external quality data (KBUDEK, İstanbul, Turkey) measured in the period from May to November 2013 were used to determine the bias. The resulting data and total allowable error rate (TEA=10%) from the Clinical Laboratory Improvement Amendments of 1988 (CLIA'88) were used to calculate the sigma level.
  
  
  RESULTS
  The calculated coefficient of variations (CVs) at the two levels, normal (QC1=36.6±2.38 mmol/mol) and pathological (QC2=84.7±2.68 mmol/mol), were 6.5% and 3.1%, respectively. The average bias between the external QC and MQ-2000 PT during the study period was 4.3%. The calculated average sigma value was 1.19.
  
  
  CONCLUSIONS
  The MQ-2000 PT HbA1c is a new analyser in the market; there is need for improvement and the method should be controlled with greater attention to ensure quality.
authors.affiliation: Department of Clinical Laboratory, Yuksek Ihtisas Education and Research Hospital, Bursa, Turkey.
authors.forename: Kağan
authors.initials: K
authors.lastname: Huysal
authors.affiliation: Department of Clinical Laboratory, Sevket Yilmaz Education and Research Hospital, Bursa, Turkey.
authors.forename: Yasemin U
authors.initials: YU
authors.lastname: Budak
mesh_terms: D001774:Blood Chemical Analysis / Q000295:instrumentation*; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation*; D003920:Diabetes Mellitus / Q000097:blood; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D007202:Indicators and Reagents; D010380:Peer Review; D011785:Quality Assurance, Health Care / Q000706:statistics & numerical data*; D015203:Reproducibility of Results
chemical_list: D006442:Glycated Hemoglobin; D007202:Indicators and Reagents
keywords: chromatography, high pressure liquid chromatography; diabetes mellitus; hemoglobin A1c protein, human