title: Transformations of summary statistics as input in meta-analysis for linear dose-response models on a logarithmic scale: a methodology developed within EURRECA.
abstract: BACKGROUND
  To derive micronutrient recommendations in a scientifically sound way, it is important to obtain and analyse all published information on the association between micronutrient intake and biochemical proxies for micronutrient status using a systematic approach. Therefore, it is important to incorporate information from randomized controlled trials as well as observational studies as both of these provide information on the association. However, original research papers present their data in various ways.
  
  
  METHODS
  This paper presents a methodology to obtain an estimate of the dose-response curve, assuming a bivariate normal linear model on the logarithmic scale, incorporating a range of transformations of the original reported data.
  
  
  RESULTS
  The simulation study, conducted to validate the methodology, shows that there is no bias in the transformations. Furthermore, it is shown that when the original studies report the mean and standard deviation or the geometric mean and confidence interval the results are less variable compared to when the median with IQR or range is reported in the original study.
  
  
  CONCLUSIONS
  The presented methodology with transformations for various reported data provides a valid way to estimate the dose-response curve for micronutrient intake and status using both randomized controlled trials and observational studies.
authors.affiliation: Division of Human Nutrition, Wageningen University and Research Centre, PO Box 8129, 6700 EV Wageningen, the Netherlands. Olga.Souverein@wur.nl
authors.forename: Olga W
authors.initials: OW
authors.lastname: Souverein
authors.forename: Carla
authors.initials: C
authors.lastname: Dullemeijer
authors.forename: Pieter
authors.initials: P
authors.lastname: van't Veer
authors.forename: Hilko
authors.initials: H
authors.lastname: van der Voet
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D004032:Diet; D004305:Dose-Response Relationship, Drug; D006801:Humans; D016014:Linear Models; D015201:Meta-Analysis as Topic; D018977:Micronutrients / Q000008:administration & dosage* / Q000494:pharmacology; D008954:Models, Biological; D016032:Randomized Controlled Trials as Topic
chemical_list: D018977:Micronutrients