title: Problems with using observational databases to compare treatments.
authors.affiliation: National Institutes of Health, Bethesda, MD 20892.
authors.forename: D P
authors.initials: DP
authors.lastname: Byar
mesh_terms: D015982:Bias; D003627:Data Interpretation, Statistical; D016208:Databases, Factual; D004812:Epidemiologic Methods; D006801:Humans; D007256:Information Systems; D013223:Statistics as Topic; D013812:Therapeutics