Table 3.
Multiple choice items of knowledge questionnaire (possible answers in parentheses). Values are numbers (percentages) with correct answers
| Item of knowledge | Evidence based information (n=785) | Standard information (n=792) |
|---|---|---|
| 1. Which disease is the occult blood test (for example, Haemoccult) supposed to detect? (irritable bowel syndrome, inflammatory bowel disease, colorectal cancer*, haemorrhoids) | 632 (80.5) | 623 (78.7) |
| 2. When can an occult blood test lead to a false positive test result? If on the day before the test (one consumed raw meat*, one consumed fish, one drunk alcohol, one smoked cigarettes) | 655 (83.4) | 632 (79.8) |
| 3. Imagine 1000 people in your age group who have positive test results in their occult blood test. How many out of these 1000 people really have colorectal cancer?† (1000, 980, 700, 400* (age 60-79), 100* (age 50-59), 10) | 369 (47.0) | 177 (22.3) |
| 4. The risk for colorectal cancer increases with age. How high do you estimate the risk for colorectal cancer to be in your age group during the next 10 years?† (1 in 761, 1 in 237* (age 50-59), 1 in 92* (age 60-69), 1 in 38* (age 70-79), 1 in 18) | 392 (49.9) | 207 (26.1) |
| 5. Screening with the occult blood test decreases the risk of dying from colorectal cancer. Imagine 1000 people start from age 50 to regularly participate in the screening programme. How many fewer people do you estimate would die from colorectal cancer? (1-2*, 8-10, 50-100, 200-400, 800-990) | 305 (38.9) | 29 (3.7) |
| 6. For colorectal cancer screening, either the occult blood test or colonoscopy may be used. It is important that studies are available that have investigated the benefit and harm of these medical tests. Please rate whether such studies are available for these tests. (“yes*/no” for occult blood test; “yes/no*” for colonoscopy) | 194 (24.7) | 52 (6.6) |
| 7. Imagine 1000 people in your age group who have negative test results in their occult blood test. Please rate how many out of these 1000 people really do not have colorectal cancer† (1000, 999* (age 50-59), 990* (age 60-79), 850, 400, 100, 10) | 376 (47.9) | 152 (19.2) |
| 8. Colonoscopy may be associated with severe side effects. Please rate what side effects may occur with colonoscopy. Please mark all correct answers. (faecal incontinence, bleeding*, bowel occlusion, bowel perforation*, death*) | 437 (55.7) | 103 (13.0) |
*Correct answer.
†Items analysed according to age of participants.