title: Confounding in community interventions.
abstract: Evaluations of community intervention projects usually use the community as the unit of analysis and employ a possibly costly cohort approach, which may not achieve sufficient power. The case-control approach, applied extensively in cancer control, may be an inexpensive alternative. Moreover, the case-control approach permits evaluation of potential confounding by factors possibly associated with the intervention. A simulation based on case-control methodology for calculating an intervention program effect (prevented fraction) demonstrates that the threat of confounding, at levels of prevented fractions in the range of 10% to 30%, is modest. Community-based interventions with lower prevented fractions are more susceptible, and their results should be considered with caution. Such boundaries may be of use to investigators in planning and evaluating community-based efforts to reduce risk and control disease.
authors.affiliation: National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia.
authors.forename: R B
authors.initials: RB
authors.lastname: Rothenberg
mesh_terms: D016022:Case-Control Studies; D015984:Causality; D015986:Confounding Factors, Epidemiologic; D006801:Humans; D016017:Odds Ratio; D011634:Public Health / Q000379:methods*; D012309:Risk-Taking