title: Evaluating the use of friend or family controls in epidemiologic case-control studies.
abstract: Traditional methodologies for identifying and recruiting controls in epidemiologic case-control studies, such as random digit dialing or neighborhood walk, suffer from declining response rates. Here, we revisit the feasibility and comparability of using alternative sources of controls, specifically friend and family controls.
  
  
  
  We recruited from a recently completed case-control study of non-Hodgkin lymphoma (NHL) among women in Los Angeles County where controls from the parent study were ascertained by neighborhood walk. We calculated participation rates and compared questionnaire responses between the friend/family controls and the original matched controls from the parent study.
  
  
  
  Of the 182 NHL case patients contacted, 111 (61%) agreed to participate in our feasibility study. 70 (63%) provided contact information for potential friend and/or family member controls. We were able to successfully contact and recruit a friend/family member for 92% of the case patients. This represented 46 friend controls and 54 family controls. Family controls significantly differed from original matched controls by sex and household income. Other characteristics were similar between friend controls and the original study's neighborhood controls.
  
  
  
  The apparent comparability of neighborhood controls to friend and family controls among respondents in this study suggests that these alternative methods of control identification can serve as a complementary source of eligible controls in epidemiologic case-control studies.
authors.affiliation: Department of Population Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, United States.
authors.forename: Charlie
authors.initials: C
authors.lastname: Zhong
authors.affiliation: Division of Preventive Medicine, University of Southern California and the Keck School of Medicine, Los Angeles, CA, United States.
authors.forename: Myles
authors.initials: M
authors.lastname: Cockburn
authors.affiliation: Division of Preventive Medicine, University of Southern California and the Keck School of Medicine, Los Angeles, CA, United States.
authors.forename: Wendy
authors.initials: W
authors.lastname: Cozen
authors.affiliation: Department of Population Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, United States.
authors.forename: Jenna
authors.initials: J
authors.lastname: Voutsinas
authors.affiliation: Department of Population Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, United States.
authors.forename: James V
authors.initials: JV
authors.lastname: Lacey
authors.affiliation: Department of Population Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, United States.
authors.forename: Jianning
authors.initials: J
authors.lastname: Luo
authors.affiliation: Department of Population Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, United States.
authors.forename: Jane
authors.initials: J
authors.lastname: Sullivan-Halley
authors.affiliation: Department of Population Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, United States.
authors.forename: Leslie
authors.initials: L
authors.lastname: Bernstein
authors.affiliation: Department of Population Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, United States. Electronic address: sowang@coh.org.
authors.forename: Sophia S
authors.initials: SS
authors.lastname: Wang
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D005190:Family; D005240:Feasibility Studies; D005260:Female; D033062:Friends; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000453:epidemiology*; D011795:Surveys and Questionnaires
keywords: Case-control studies; Epidemiologic methods; Non-Hodgkin lymphoma