title: Patient results and laboratory test accuracy.
abstract: OBJECTIVE
  Traditional quality control materials used for monitoring the clinical laboratory test accuracy might be non-commutable with patient samples and may not detect systematic errors. The aim of this paper is to describe a method to monitor inter-instrument bias using result distributions that are independent of the control's commutability.
  
  
  METHODS
  Serum calcium data collected within a laboratory network were assessed. A reference interval was calculated using a computerized, indirect Hoffmann's algorithm using all data across a laboratory network without excluding any results. Results outside the reference interval were considered as the zero-bias distribution. Three allowable bias levels were then calculated to determine the corresponding shift in abnormal results for each bias level in both directions from the zero-bias distribution. The observed result distributions in three laboratories within the network were compared for bias performance after one year of the reference interval study.
  
  
  RESULTS
  Performance levels for bias were: minimum allowable < 1.27 percent; desirable < 0.85 percent; and optimal < 0.42 percent. Zero bias result distribution above and below the reference interval for calcium was 3.92 percent and 2.53 percent respectively. All three laboratories performed within the desirable allowable bias level.
  
  
  CONCLUSIONS
  Bias-monitoring process using patient result distributions allows managers to: assess systematic error between laboratory instruments; improve laboratory quality control; and strengthen patient risk management.
authors.forename: Alexander
authors.initials: A
authors.lastname: Katayev
authors.forename: James K
authors.initials: JK
authors.lastname: Fleming
mesh_terms: D015982:Bias; D001774:Blood Chemical Analysis / Q000379:methods / Q000592:standards*; D002118:Calcium / Q000097:blood*; D002984:Clinical Laboratory Information Systems / Q000706:statistics & numerical data; D016208:Databases, Factual / Q000706:statistics & numerical data; D006801:Humans; D007753:Laboratories / Q000592:standards / Q000706:statistics & numerical data; D011785:Quality Assurance, Health Care / Q000379:methods / Q000592:standards*; D012016:Reference Values; D015203:Reproducibility of Results; D014481:United States
chemical_list: D002118:Calcium