title: Correction of an unexpected increasing trend in glucose measurements during 7 years recruitment to a cohort study.
abstract: OBJECTIVE
  To study an unexpected, significant increase in glucose measurements during 7 year recruitment to a cohort study.
  
  
  METHODS
  Measurements of quality control solutions and blood glucose in pregnant women were done by Accu-Chek Sensor glucometer. Time-trends were analysed by regression models and control charts.
  
  
  RESULTS
  Cohort measurements were de-trended by weighted linear regressions based on independent control values.
  
  
  CONCLUSIONS
  Biologically implausible trends in data can be corrected by using independent control values.
authors.affiliation: Norwegian Resource Centre for Women's Health, Division of Obstetrics and Gynaecology, Oslo University hospital Rikshospitalet, Norway. k.f.froslie@medisin.uio.no
authors.forename: K F
authors.initials: KF
authors.lastname: Frøslie
authors.forename: K
authors.initials: K
authors.lastname: Godang
authors.forename: J
authors.initials: J
authors.lastname: Bollerslev
authors.forename: T
authors.initials: T
authors.lastname: Henriksen
authors.forename: J
authors.initials: J
authors.lastname: Røislien
authors.forename: M B
authors.initials: MB
authors.lastname: Veierød
authors.forename: E
authors.initials: E
authors.lastname: Qvigstad
mesh_terms: D001786:Blood Glucose; D015331:Cohort Studies; D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D019719:Diagnostic Equipment / Q000592:standards*; D005260:Female; D005951:Glucose Tolerance Test / Q000592:standards*; D006801:Humans; D011247:Pregnancy; D011786:Quality Control; D012015:Reference Standards; D012044:Regression Analysis
chemical_list: D001786:Blood Glucose