title: Application of data screening to drug exposure in large risk factor studies of birth defects.
abstract: BACKGROUND
  Birth defects are the leading cause of infant death. While causes of most are unknown, those that might be due to medication use are among the most preventable. This study describes an approach to identifying those medications that most warrant attention by using a "screen" program that calculates odds ratios for pairs of exposures and specific birth defects.
  
  
  METHODS
  We discuss the development of this tool and illustrate its application to two large risk factor studies, the Slone Epidemiology Center's Birth Defects Study and the Centers for Disease Control and Prevention's National Birth Defects Prevention Study, ideal settings for the systematic study of risks and relative safety of drugs in relation to birth defects while recognizing the inherent limitations of such an approach.
  
  
  RESULTS
  Suggestions for establishing criteria for exposures and outcomes that balance the need for specific details with the practical considerations of sample size and volume of output are presented. Selection of appropriate exposure reference categories and control groups is also discussed, as well as the need to address potential confounding. An example that motivated a detailed investigation of possible associations between a medication (butalbital) and selected specific birth defects is provided.
  
  
  CONCLUSIONS
  While screening programs such as the one described can be a valuable tool for exploring potential associations in large data bases, they must be applied with caution. The issue of multiple testing and chance findings is a major concern. While statistics are a necessary component, human judgment must be an integral part of the process.
authors.affiliation: Slone Epidemiology Center at Boston University, Boston, Massachusetts.
authors.forename: Carol
authors.initials: C
authors.lastname: Louik
authors.affiliation: Slone Epidemiology Center at Boston University, Boston, Massachusetts.|Boston University School of Public Health, Boston, Massachusetts.
authors.forename: Martha
authors.initials: M
authors.lastname: Werler
authors.affiliation: Massachusetts Department of Public Health, Boston, Massachusetts.
authors.forename: Marlene
authors.initials: M
authors.lastname: Anderka
authors.affiliation: Slone Epidemiology Center at Boston University, Boston, Massachusetts.
authors.forename: Allen A
authors.initials: AA
authors.lastname: Mitchell
mesh_terms: D000014:Abnormalities, Drug-Induced / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D016022:Case-Control Studies; D002487:Centers for Disease Control and Prevention, U.S.; D000013:Congenital Abnormalities / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D016208:Databases, Factual; D005260:Female; D006801:Humans; D004364:Pharmaceutical Preparations / Q000008:administration & dosage*; D011159:Population Surveillance; D011247:Pregnancy; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
chemical_list: D004364:Pharmaceutical Preparations
keywords: birth defects; data screening; large databases; medication use; statistics