title: New decision criteria for selecting delta check methods based on the ratio of the delta difference to the width of the reference range can be generally applicable for each clinical chemistry test item.
abstract: BACKGROUND
  Many laboratories use 4 delta check methods: delta difference, delta percent change, rate difference, and rate percent change. However, guidelines regarding decision criteria for selecting delta check methods have not yet been provided. We present new decision criteria for selecting delta check methods for each clinical chemistry test item.
  
  
  METHODS
  We collected 811,920 and 669,750 paired (present and previous) test results for 27 clinical chemistry test items from inpatients and outpatients, respectively. We devised new decision criteria for the selection of delta check methods based on the ratio of the delta difference to the width of the reference range (DD/RR). Delta check methods based on these criteria were compared with those based on the CV% of the absolute delta difference (ADD) as well as those reported in 2 previous studies.
  
  
  RESULTS
  The delta check methods suggested by new decision criteria based on the DD/RR ratio corresponded well with those based on the CV% of the ADD except for only 2 items each in inpatients and outpatients. Delta check methods based on the DD/RR ratio also corresponded with those suggested in the 2 previous studies, except for 1 and 7 items in inpatients and outpatients, respectively.
  
  
  CONCLUSIONS
  The DD/RR method appears to yield more feasible and intuitive selection criteria and can easily explain changes in the results by reflecting both the biological variation of the test item and the clinical characteristics of patients in each laboratory. We suggest this as a measure to determine delta check methods.
authors.affiliation: Department of Laboratory Medicine, Asan Medical Center and University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Sang Hyuk
authors.initials: SH
authors.lastname: Park
authors.forename: So-Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Woochang
authors.initials: W
authors.lastname: Lee
authors.forename: Sail
authors.initials: S
authors.lastname: Chun
authors.forename: Won-Ki
authors.initials: WK
authors.lastname: Min
mesh_terms: D000410:Alanine Transaminase / Q000097:blood; D000469:Alkaline Phosphatase / Q000097:blood; D001219:Aspartate Aminotransferases / Q000097:blood; D001663:Bilirubin / Q000097:blood; D001806:Blood Urea Nitrogen; D016461:Chemoembolization, Therapeutic; D019963:Clinical Chemistry Tests / Q000379:methods / Q000592:standards*; D003401:Creatine / Q000097:blood; D003663:Decision Trees; D006801:Humans; D012016:Reference Values; D006435:Renal Dialysis; D014527:Uric Acid / Q000097:blood
chemical_list: D014527:Uric Acid; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D000469:Alkaline Phosphatase; D003401:Creatine; D001663:Bilirubin