July 5, 2019

Financial incentives increase stool testing


Dr. Beverly Green's research explores how to help decrease disparities in screening for colon cancer. 

By Beverly B. Green, MD, MPH, a senior researcher at Kaiser Permanente Washington Health Research Institute (KPWHRI) and a family medicine physician at Washington Permanente Medical Group.

Our research team has been trying to find ways to encourage more people to receive regular screening for cancers of the colon and rectum. How about offering them money? That’s what we did in our latest study, reported as “Financial Incentives to Increase Colorectal Cancer Screening Uptake and Decrease Disparities: A Randomized Controlled Trial,” in JAMA Network Open.

As part of our Systems of Support to Increase Colorectal Cancer Screening and Follow-up (SOS) study, we randomly assigned Kaiser Permanente Washington patients overdue for colorectal cancer screening to receive either:

  • A mailed fecal immunochemical test (FIT), in which stool samples are taken at home and mailed to a lab; 
  • the test plus $10; or
  • the test plus entry in a “lottery,” with a 1 in 10 chance of $50 for completing testing.

The most important thing we learned was that incentives worked to increase FIT (a 7.7 percent rise with $10, and a 7.1 percent rise with the lottery)—but not colonoscopy.  And financial incentives may decrease the screening disparities among some disadvantaged groups: The financial rewards increased use of FIT by 38 percent in patients with Medicaid insurance—significantly more effective than in the other patients. And we saw a nonsignificant trend toward decreasing CRC screening disparities in some non-white racial/ethnic groups. 

Nudges and rewards

Why did the financial incentive make a difference?  Economic theory suggests that adding a reward to a nudge may be key. Mailed FITs are considered nudges, which make the right thing to do, the easy thing to do. By contrast, money is a reward, which supports and reinforces desirable behavior by making you as likely to get a chore done as you would be to pursue activities that offer an immediate benefit, such as watching TV.

We found with psychometric assessments (patients’ self-reported answers to a survey with validated questions) that incentives seemed to counteract “present-time bias.” That means patients may have been prioritizing things with immediate benefit over those whose benefits are in the future (such as the health protective effects of cancer screening). So the incentives were likely most useful for those people who were already predisposed to screen and had some intrinsic motivation to do it, but who had put it off. 

What’s next?

This research taught us several lessons, including that small incentives are probably most effective for FIT (an easy-to-do single activity), rather than colonoscopy (a more complex procedure). Incentives also seem more effective when used in settings like Kaiser Permanente Washington, where usual care already includes many activities to encourage screening for CRC.

Incentives did not lead to an additional benefit over mailed FIT alone in those who had never screened before. So, like previous studies, ours suggests that incentives may not work for the hardest-to-reach groups: people who have never been screened, the most disadvantaged populations, and people less aware of the benefits of CRC screening.

We’ll keep studying how best to encourage screening in these groups.

I’m grateful to all my coauthors: Melissa L. Anderson, MS, Andrea J. Cook, PhD, Jessica Chubak, PhD, Sharon Fuller, and Kilian J. Kimbel, of KPWHRI; Jeffrey T. Kullgren, MD, MS, MPH, of Veterans Affairs Ann Arbor Healthcare System and University of Michigan Medical School; Richard T. Meenan, PhD, of Kaiser Permanente Northwest Center for Health Research, in Portland; and Sally W. Vernon, PhD, of University of Texas School of Public Health, in Houston. A grant from the National Cancer Institute supported our work.​​​​


Andrea J. Cook, PhD

Senior Biostatistics Investigator
Kaiser Permanente Washington Health Research Institute

Melissa L. Anderson, MS

Principal Collaborative Biostatistician
Kaiser Permanente Washington Health Research Institute

Melissa L. Anderson, MS

Principal Collaborative Biostatistician
Kaiser Permanente Washington Health Research Institute

Jessica Chubak, PhD

Senior Investigator
Kaiser Permanente Washington Health Research Institute

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