Objective

To compare the effectiveness of including or not including numerical descriptions of benefits and risks in a colorectal cancer (CRC) screening decision aid on increasing CRC screening

Study Design

Design Elements	Description
Design	Randomized controlled trial
Population	688 patients receiving primary care, ages 50–75, past due for CRC screening
Interventions/ Comparators	CRC screening decision aid that included numerical description of benefits and risks, absolute risk of CRC, risk reduction from CRC screening, and frequency of complications due to screening CRC screening decision aid with text-based description of benefits and risks
Outcomes	Primary: proportion of patients receiving CRC screening Secondary: intent to get any CRC screening, intent to get stool blood test, intent to get colonoscopy, knowledge of CRC and screening, perceived benefits of and barriers to CRC screening, perceived risk of CRC, decision conflict
Timeframe	6-month follow-up for primary outcomes

This randomized controlled trial compared the effectiveness of including or not including numerical data in a CRC screening decision aid on increasing the proportion of patients receiving screening among those viewing each decision aid.

The research team randomly assigned patients to one of two groups. In both groups, patients viewed a computer-based decision aid that compared two screening options, colonoscopy and stool blood test, presenting benefits and risks associated with each. For the first group, the decision aid provided this information using numerical descriptions of risk, such as the number out of 1,000 patients who will die from colon cancer or the number having complications following colonoscopy. The second group’s decision aid presented these risks with words only, using terms such as often or some.

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

The research team surveyed patients about their knowledge of and attitudes toward CRC screening and screening intent before and immediately after viewing the decision aid. Six months later, the team looked at patients’ electronic health records to see who had received CRC screening.

Patients, patient advocates, and physicians helped create the decision aids and share results.

Results

The two groups did not differ in the proportion who received CRC screening within six months of viewing the decision aid. About 29% of patients in both groups received CRC screening.

Compared with patients who viewed the text-only decision aid, patients who viewed the numerical decision aid had statistically significantly greater increases in

• Intent to get a stool blood test (p=0.007)
• Knowledge of CRC and screening (p=0.007)
• Perceived personal risk of getting CRC in their lifetimes (p<0.001)

The groups did not differ in intent to get a colonoscopy, perceived benefits of and barriers to CRC screening, perceived comparative risk for CRC, and decision conflict. The patients’ level of numeracy did not affect the results.

After viewing the decision aid, compared to beforehand, patients in both groups had significantly (p<0.001)

• Greater intent to get any CRC screening
• Greater intent to get a stool blood test
• Higher ratings of perceived benefits of CRC screening
• Lower ratings of perceived barriers for CRC screening
• Lower ratings of decisional conflict

Limitations

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

Conclusions and Relevance

Including numerical information in a decision aid did not affect the proportion of patients getting CRC screening, compared with a decision aid without numerical information. Patients showed improvement in most other outcomes after viewing either decision aid.

Future Research Needs

Future research could compare decision aids with and without numerical descriptions of risks and benefits for other types of healthcare decisions.