Potential Biases Introduced by Conflating Screening and Diagnostic Testing in Colorectal Cancer Screening Surveillance.
BACKGROUND
Screening and postsymptomatic diagnostic testing are often conflated in cancer screening surveillance research. We examined the error in estimated colorectal cancer screening prevalence due to the conflation of screening and diagnostic testing.


METHODS
Using data from the 2008 National Health Interview Survey, we compared weighted prevalence estimates of the use of all testing (screening and diagnostic) and screening in at-risk adults and calculated the overestimation of screening prevalence across sociodemographic groups.


RESULTS
The population screening prevalence was overestimated by 23.3%, and the level of overestimation varied widely across sociodemographic groups (median, 22.6%; mean, 24.8%). The highest levels of overestimation were in non-Hispanic white females (27.4%), adults ages 50-54 years (32.0%), and those with the highest socioeconomic vulnerability [low educational attainment (31.3%), low poverty ratio (32.5%), no usual source of health care (54.4%), and not insured (51.6%); all P < 0.001].


CONCLUSIONS
When the impetus for testing was not included, colorectal cancer screening prevalence was overestimated, and patterns of overestimation often aligned with social and economic vulnerability. These results are of concern to researchers who use survey data from the Behavioral Risk Factor Surveillance System (BRFSS) to assess cancer screening behaviors, as it is currently not designed to distinguish diagnostic testing from screening.


CONCLUSIONS
Surveillance research in cancer screening that does not consider the impetus for testing risks measurement error of screening prevalence, impeding progress toward improving population health. Ultimately, to craft relevant screening benchmarks and interventions, we must look beyond "what" and "when" and include "why."
Institute for Health Research and Policy, University of Illinois at Chicago, Chicago, Illinois. eabecker@uic.edu.
Elizabeth A
EA
Becker
The Center for Medicine, Health, and Society, Vanderbilt University, Nashville, Tennessee.
Derek M
DM
Griffith
Institute for Social Research, University of Michigan, Ann Arbor, Michigan.
Brady T
BT
West
Department of Health Behavior and Health Education, University of Michigan School of Public Health, Ann Arbor, Michigan.
Nancy K
NK
Janz
Department of Health Behavior and Health Education, University of Michigan School of Public Health, Ann Arbor, Michigan.
Ken
K
Resnicow
Department of Surgery, University of Michigan Health System, Ann Arbor, Michigan.
Arden M
AM
Morris
D000368:Aged; D000369:Aged, 80 and over; D040343:Behavioral Risk Factor Surveillance System; D015982:Bias; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D055088:Early Detection of Cancer / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D014481:United States / Q000453:epidemiology