Neighborhood effects in a behavioral randomized controlled trial

Sandi L Pruitt; Tammy Leonard; James Murdoch; Amy Hughes; Amy McQueen; Samir Gupta

doi:10.1016/j.healthplace.2014.10.001

Neighborhood effects in a behavioral randomized controlled trial

Health Place. 2014 Nov:30:293-300. doi: 10.1016/j.healthplace.2014.10.001. Epub 2014 Nov 21.

Authors

Sandi L Pruitt¹, Tammy Leonard², James Murdoch³, Amy Hughes⁴, Amy McQueen⁵, Samir Gupta⁶

Affiliations

¹ 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.
² Economics Department, University of Dallas, 1845 E. Northgate Dr., Irving, TX 75026, United States.
³ School of Economic, Political, and Policy Sciences, University of Texas-Dallas, 800W. Campbell Rd, GR31, Richardson, TX 75080, USA.
⁴ 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.
⁵ 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.
⁶ 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.

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.

Keywords: Cancer screening; Neighborhood; Peer relationships; Randomized controlled trial; Spatial autocorrelation.

Publication types

Randomized Controlled Trial
Research Support, Non-U.S. Gov't

MeSH terms

Colorectal Neoplasms / diagnosis
Early Detection of Cancer / statistics & numerical data
Female
Health Behavior*
Humans
Male
Middle Aged
Patient Acceptance of Health Care* / statistics & numerical data
Residence Characteristics*

Grants and funding

L60 MD003664/MD/NIMHD NIH HHS/United States