title: Neighborhood effects in a behavioral randomized controlled trial.
abstract: Randomized controlled trials (RCTs) of interventions intended to modify health behaviors may be influenced by neighborhood effects which can impede unbiased estimation of intervention effects. Examining a RCT designed to increase colorectal cancer (CRC) screening (N=5628), we found statistically significant neighborhood effects: average CRC test use among neighboring study participants was significantly and positively associated with individual patient's CRC test use. This potentially important spatially-varying covariate has not previously been considered in a RCT. Our results suggest that future RCTs of health behavior interventions should assess potential social interactions between participants, which may cause intervention arm contamination and may bias effect size estimation.
authors.affiliation: Department of Clinical Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA; Harold C. Simmons Comprehensive Cancer Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9169, USA. Electronic address: Sandi.Pruitt@utsouthwestern.edu.
authors.forename: Sandi L
authors.initials: SL
authors.lastname: Pruitt
authors.affiliation: Economics Department, University of Dallas, 1845 E. Northgate Dr., Irving, TX 75026, United States.
authors.forename: Tammy
authors.initials: T
authors.lastname: Leonard
authors.affiliation: School of Economic, Political, and Policy Sciences, University of Texas-Dallas, 800W. Campbell Rd, GR31, Richardson, TX 75080, USA.
authors.forename: James
authors.initials: J
authors.lastname: Murdoch
authors.affiliation: Department of Clinical Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA; School of Economic, Political, and Policy Sciences, University of Texas-Dallas, 800W. Campbell Rd, GR31, Richardson, TX 75080, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Hughes
authors.affiliation: Division of Health Behavior Research, Department of Medicine, Washington University School of Medicine, 660 South Euclid Avenue Campus, Box 8005, St. Louis, MO 63110, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: McQueen
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Moores Cancer Center, University of California, San Diego, CA, USA; Department of Veterans Affairs, San Diego Healthcare System, 3350 La Jolla Village Dr MC 111D, San Diego, CA 92161, USA.
authors.forename: Samir
authors.initials: S
authors.lastname: Gupta
mesh_terms: D015179:Colorectal Neoplasms / Q000175:diagnosis; D055088:Early Detection of Cancer / Q000706:statistics & numerical data; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D008875:Middle Aged; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data; D012111:Residence Characteristics
keywords: Cancer screening; Neighborhood; Peer relationships; Randomized controlled trial; Spatial autocorrelation