title: Gestational diabetes mellitus prevalence: Effect of the laboratory analytical variation.
abstract: OBJECTIVE
  To highlight the effect of laboratory analytic variation, assessed by glucose (a) total analytic laboratory error (TAEL) present in one index laboratory and (b) total recommended allowable error (TAEa) universally applicable to all laboratories, on the prevalence of gestational diabetes mellitus (GDM).
  
  
  METHODS
  2337 pregnant women underwent a 75-g oral glucose tolerance test (OGTT) for universal GDM screening. Since the true value of every laboratory result fluctuates within a range, the glucose TAEL and TAEa were used to define a lower and an upper diagnostic threshold (95% confidence interval, CI) for the three glucose OGTT cut-offs of the criteria of the American Diabetes Association, ADA (2003); the Canadian Diabetes Association, CDA (2013) and the International Association of Diabetes and Pregnancy Study Groups, IADPSG (2010).
  
  
  RESULTS
  For the ADA, CDA and IADPSG criteria, respectively, the GDM prevalence [95% CI, (glucose TAEL) (glucose TAEa)] was 13.3% [(8.0-21.8) (6.3-25.9)], 30% [(17.3-53.1) (14.3-61.3)] and 45.3% [(27.0-71.0) (22.3-79.2)]. Using the lower and higher assigned OGTT glucose thresholds for TAEL, respectively, among the different criteria, either 200 (8.6%)-601 (25.7%) additional or 122 (5.2%)-426 (18.3%) fewer women would be identified with GDM (p<0.0001).
  
  
  CONCLUSIONS
  Independent of the diagnostic criteria, any reported GDM prevalence can potentially vary between one half to two times even for laboratories meeting recommended quality specifications. To avoid misclassifying women with GDM substantially, individual laboratories can significantly reduce this disparity by improving analytic performance. All physicians must ensure that their laboratory meets acceptable quality standards for optimal patient care.
authors.affiliation: Department of Pathology, College of Medicine, UAE University, Al Ain, United Arab Emirates. Electronic address: magarwal7@gmail.com.
authors.forename: M M
authors.initials: MM
authors.lastname: Agarwal
authors.affiliation: Department of Pathology, Tawam Hospital, Al Ain, United Arab Emirates.
authors.forename: G S
authors.initials: GS
authors.lastname: Dhatt
authors.affiliation: Department of Pathology, Tawam Hospital, Al Ain, United Arab Emirates.
authors.forename: Y
authors.initials: Y
authors.lastname: Othman
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis / Q000379:methods / Q000592:standards*; D001786:Blood Glucose / Q000032:analysis*; D016640:Diabetes, Gestational / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*; D003951:Diagnostic Errors / Q000706:statistics & numerical data; D005260:Female; D005951:Glucose Tolerance Test / Q000592:standards; D006801:Humans; D008403:Mass Screening / Q000379:methods / Q000592:standards*; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods / Q000592:standards; D015995:Prevalence; D012016:Reference Values; D015203:Reproducibility of Results; D014479:United Arab Emirates / Q000453:epidemiology
chemical_list: D001786:Blood Glucose
keywords: Analytic error; Bias; Gestational diabetes mellitus; Glucose; Imprecision; Prevalence