Results Summary

What was the research about?

Decision aids help people choose between two or more healthcare options based on what is most important to them. Decision aids may include numbers to help show benefits and risks. Researchers don’t know if using numbers makes decision aids more useful or more confusing.

In this study, the research team compared two decision aids that showed risks and benefits of two ways to screen for colorectal cancer, or CRC: colonoscopy or a test for blood in the stool. The team assigned patients by chance to use either a

  • Decision aid with numbers to describe the risks and benefits of CRC screening. For example, “Four out of 1,000 people who have a colonoscopy will have to go to the hospital due to heavy bleeding.”
  • Decision aid with words instead of numbers to describe risks and benefits. For example, “Very rarely, people having a colonoscopy need to go to the hospital due to heavy bleeding.”

What were the results?

Similar numbers of patients from each group, about 29 percent, got CRC screenings in the six months after they used the decision aids.

Compared with patients who viewed the decision aid that used words, more patients who viewed the decision aid with numbers

  • Planned to get a stool blood test
  • Felt they were at risk for getting CRC in their lifetimes
  • Answered knowledge questions about CRC and screening correctly

The groups didn’t differ in intent to get a colonoscopy, ratings of CRC screening benefits, worry about problems getting CRC screening, or conflict about their screening decisions. Patients’ ability to use numbers didn’t affect the results.

Comparing before and after viewing the decision aids, both groups said they were

  • More likely to get some type of CRC screening
  • More likely to get a stool blood test
  • More convinced of the benefits of CRC screening
  • Less worried about problems getting CRC screening
  • Less conflicted about their decisions about whether to get screening

In both groups, patients’ knowledge about CRC and screening increased.

Who was in the study?

The study included 688 patients ages 50–75 who were past due for CRC screening. Of these, 61 percent were white, 28 percent were black, 1 percent were Asian, and 10 percent were either multiple races, other races, or did not answer the question. The average age was 59, and 60 percent were women. Patients received care at clinics in two healthcare systems in the Indianapolis area.

What did the research team do?

The research team created the decision aids, which patients could view on a computer. The decision aids had slides with text, pictures, and audio. Patients used either the decision aid that used numbers or the one with words. Patients filled out a survey before and after viewing the decision aid. The team looked at health records six months later to see how many patients had received CRC screening.

What were the limits of the study?

Patients lived in one midwestern state. Results may differ for patients in other areas.

Future research could compare decision aids that do and don’t use numbers for other types of health problems and in other areas.

How can people use the results?

Decision aid designers can use the results of the study to help decide whether to use numbers when presenting information to patients.

Final Research Report

View this project's final research report.

Peer-Review Summary

Peer review of PCORI-funded research helps make sure the report presents complete, balanced, and useful information about the research. It also assesses how the project addressed PCORI’s Methodology Standards. During peer review, experts read a draft report of the research and provide comments about the report. These experts may include a scientist focused on the research topic, a specialist in research methods, a patient or caregiver, and a healthcare professional. These reviewers cannot have conflicts of interest with the study.

The peer reviewers point out where the draft report may need revision. For example, they may suggest ways to improve descriptions of the conduct of the study or to clarify the connection between results and conclusions. Sometimes, awardees revise their draft reports twice or more to address all of the reviewers’ comments. 

Peer reviewers commented, and the researchers made changes or provided responses. The comments and responses included the following:

  • The reviewers asked for an explanation of the study design. In particular, they wanted to know why the public deliberation portion, which was qualitative, followed the quantitative randomized trial instead of preceding the trial to inform its design. The researchers explained that in this case there was enough previous research to inform the design of the randomized trial, and the results of the trial were then used to inform the public deliberation materials like presentations and the briefing book.
  • The reviewers suggested that there may have been different study outcomes based on prior screening experience and encouraged the researchers to describe the sample participants’ screening history at least, if not able to stratify results by screening history. The researchers explained they did not have sufficiently reliable data on participants’ previous screening history to report these results or to stratify by screening history.
  • The reviewers expressed concern that no one in the public deliberation panel had opted against colorectal cancer (CRC) screening, which made it difficult to assess whether the presentations to the panel provided a balanced view of screening. The researchers explained that while they strove to maximize the diversity of the panel members in race, age, and educational attainment, they could not assure diversity of screening attitudes. The researchers added a discussion to the report about the lack of participants in the discussion panel who had not undergone CRC screening. The researchers noted that the panel did discuss the risks of screening and why people might choose not to screen.
  • The reviewers also noted that the panel was not broadly representative because only a small portion of people contacted responded to the invitation. The researchers agreed that the participants in the panel were not a random sample but noted that in selecting a small subset of the group that responded to the original invitation, care was taken to meet diversity goals. However, the researchers acknowledged selection bias in this process as a study limitation.

Conflict of Interest Disclosures

Project Information

Peter H. Schwartz, MD, PhD
Indiana University
Describing the Comparative Effectiveness of Colorectal Cancer Screening Tests: The Impact of Quantitative Information

Key Dates

September 2014
June 2019

Study Registration Information


Has Results
Award Type
Health Conditions Health Conditions These are the broad terms we use to categorize our funded research studies; specific diseases or conditions are included within the appropriate larger category. Note: not all of our funded projects focus on a single disease or condition; some touch on multiple diseases or conditions, research methods, or broader health system interventions. Such projects won’t be listed by a primary disease/condition and so won’t appear if you use this filter tool to find them. View Glossary
Populations Populations PCORI is interested in research that seeks to better understand how different clinical and health system options work for different people. These populations are frequently studied in our portfolio or identified as being of interest by our stakeholders. View Glossary
Intervention Strategy Intervention Strategies PCORI funds comparative clinical effectiveness research (CER) studies that compare two or more options or approaches to health care, or that compare different ways of delivering or receiving care. View Glossary
State State The state where the project originates, or where the primary institution or organization is located. View Glossary
Last updated: August 21, 2023