title: [Propensity score analysis in observational research: application to a study of prophylaxis against venous thromboembolism].
abstract: BACKGROUND
  In observational studies, a significant difference in the outcomes between treated and untreated patients may be observed in absence of treatment effect and caused by differences in baseline characteristics.
  
  
  METHODS
  Propensity score analysis is a post hoc adjustment method which consists in deriving the conditional probability of receiving the treatment for a patient given his measured baseline characteristics (i.e., the propensity score). Matching each treated patient to an untreated one who has the nearest propensity score tends to balance baseline characteristics between the two groups and reduce the risk for overt bias. Then, the outcomes can be compared between matched treated and untreated patients.
  
  
  CONCLUSIONS
  Propensity score analysis is relevant for clinical conditions and treatments for which randomized controlled trials are unlikely to be conducted. However, propensity analysis cannot adjust for unmeasured characteristics and sensitivity analysis should be performed to assess how sensitive the conclusions are to potential confounding factors.
authors.affiliation: Laboratoire THEMAS, TIMC, UMR CNRS 5525, centre hospitalier universitaire de Grenoble, université Joseph-Fourier, 38043 Grenoble, France. jlabarere@chu-grenoble.fr
authors.forename: J
authors.initials: J
authors.lastname: Labarère
authors.forename: J-L
authors.initials: JL
authors.lastname: Bosson
authors.forename: P
authors.initials: P
authors.lastname: François
authors.forename: M J
authors.initials: MJ
authors.lastname: Fine
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage / Q000627:therapeutic use; D005343:Fibrinolytic Agents / Q000008:administration & dosage / Q000627:therapeutic use; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D016015:Logistic Models; D015233:Models, Statistical; D015337:Multicenter Studies as Topic; D015999:Multivariate Analysis; D019370:Observation; D016017:Odds Ratio; D012372:ROC Curve; D016032:Randomized Controlled Trials as Topic; D013997:Time Factors; D016896:Treatment Outcome; D018608:Ultrasonography, Doppler; D054556:Venous Thromboembolism / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000517:prevention & control* / Q000628:therapy
chemical_list: D000925:Anticoagulants; D005343:Fibrinolytic Agents; D006495:Heparin, Low-Molecular-Weight