title: Causal inference algorithms can be useful in life course epidemiology.
abstract: OBJECTIVE
  Life course epidemiology attempts to unravel causal relationships between variables observed over time. Causal relationships can be represented as directed acyclic graphs. This article explains the theoretical concepts of the search algorithms used for finding such representations, discusses various types of such algorithms, and exemplifies their use in the context of obesity and insulin resistance.
  
  
  METHODS
  We investigated possible causal relations between gender, birth weight, waist circumference, and blood glucose level of 4,081 adult participants of the Prevention of REnal and Vascular ENd-stage Disease study. The latter two variables were measured at three time points at intervals of about 3 years.
  
  
  RESULTS
  We present the resulting causal graphs, estimate parameters of the corresponding structural equation models, and discuss usefulness and limitations of this methodology.
  
  
  CONCLUSIONS
  As an exploratory method, causal graphs and the associated theory can help construct possible causal models underlying observational data. In this way, the causal search algorithms provide a valuable statistical tool for life course epidemiological research.
authors.affiliation: Department of Epidemiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, PO Box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: slabastide@xs4all.nl.
authors.forename: Sacha
authors.initials: S
authors.lastname: la Bastide-van Gemert
authors.affiliation: Department of Epidemiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, PO Box 30.001, 9700 RB Groningen, The Netherlands.
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Stolk
authors.affiliation: Department of Epidemiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, PO Box 30.001, 9700 RB Groningen, The Netherlands.
authors.forename: Edwin R
authors.initials: ER
authors.lastname: van den Heuvel
authors.affiliation: Department of Epidemiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, PO Box 30.001, 9700 RB Groningen, The Netherlands.
authors.forename: Václav
authors.initials: V
authors.lastname: Fidler
mesh_terms: D000328:Adult; D000465:Algorithms; D001699:Biometry / Q000379:methods; D001724:Birth Weight; D001786:Blood Glucose / Q000378:metabolism; D015984:Causality; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000453:epidemiology; D008390:Markov Chains; D012737:Sex Factors; D014652:Vascular Diseases / Q000097:blood / Q000453:epidemiology; D055105:Waist Circumference
chemical_list: D001786:Blood Glucose
keywords: Causal graphs; Causality; Cohort studies; Life course epidemiology; Metabolic syndrome; Search algorithms