Table 1 Summary of study measures
Measure | Booklet | Repeated measure? | Scoring system | Scoring system and interpretation |
|---|---|---|---|---|
Intention to undergo colonoscopy | Scenario Booklet | Yes, following each risk scenario. | Single question to measure intention to accept an offer of colonoscopy as a proxy measure for behaviour if receiving that letter. | N/A. |
Decisional conflict | Scenario Booklet | Yes, following each risk scenario. | The informed subscore (items 1–3) from the Decisional Conflict Scale [19] was used to assess the extent to which participants felt informed about their decisions. These items are: “I know which options are available to me”, “I know the benefits of each option” and “I know the risks and side effects of each option”, scored on a 7-point scale from “strongly agree” to “strongly disagree”. | In accordance with scoring system supplied with the tool: responses to each of the three items scored on a scale from 0 to 6 and total score calculated by multiplying the average of the three scores by 16.6 to give a score between 0 and 100. A lower score indicates a more informed choice. Scores lower than 25 are associated with following through with decisions whereas scores greater than 37.5 are associated with decision delay or feeling unsure about implementation of the decision [19]. |
Planned behaviour | Scenario Booklet | Yes, following each risk scenario. | Two additional 7-point Likert scale responses (from “strongly agree” to “strongly disagree”) to two statements: “If I received information that (1) my risk of bowel cancer was 1 in 40, (2) my risk of bowel cancer was high or (3) the result of the test I provided showed that further investigation is required, then I would intend to have a colonoscopy” and “If I was told that (1) I had a 1 in 40 chance of having bowel cancer, (2) I was in the group at highest risk of bowel cancer or (3) my screening test was abnormal meaning that there was a risk I had bowel cancer, then I would definitely choose to have a colonoscopy”. | Scores ranged from 1 to 7 for each statement, with a higher score representing greater agreeability with the statement. |
Knowledge | Questionnaire Booklet | No | Eight questions (four concept, four numerical); 1 point per correct response with the exception the numerical question relating to the number of people surviving bowel cancer if detected early, worth 2 points. | Maximum knowledge score of 9. As with Smith et al. [16] a pass mark of 50% or greater (≥ 5) was used to determine whether or not knowledge was adequate. |
Attitudes | Questionnaire Booklet | No | Nine-item scale scored on a 5-point Likert scale from “strongly agree” to “strongly disagree”. Items included discomfort and embarrassment during colonoscopy, side-effects of bowel preparation and beliefs around reducing the risk of dying from bowel cancer. | The range for the total score was 9 to 45. A higher score reflected a more positive attitude towards having a colonoscopy. In keeping with Smith et al. [16], the median value of the sample was used to classify participants’ attitudes towards colonoscopy as being either positive or negative. |
Emotional responses | Questionnaire Booklet | No | The questionnaire measured anxiety using a previously-validated six-item version of the State Trait Anxiety Inventory (STAI) [20]. An example item is the statement “I am worried”, with a choice of four responses on a scale from “not at all” to “very much”. | The scoring system was developed to allow comparison with the normative values given for the original 40-item scale [21]. Total possible scores ranged from 20 to 80 with a higher score indicating a higher level of anxiety. |
Ease-of-understanding and acceptability | Questionnaire Booklet | No | Two Likert-type questions: “I found the information presented easy to understand” and “I found the information presented distressing” scored on a 7-point scale from “strongly agree” to “strongly disagree”. | Scores ranged from 1 to 7 for each statement, with a higher score representing greater agreeability with the statement. |
Previous colonoscopy | Questionnaire Booklet | No | Single question for participants if they had previously had a colonoscopy; Yes, No, or Unsure. | N/A. |
Additional thoughts on materials | Questionnaire Booklet | No | Open-ended question encouraging additional free text comments. | Thematic qualitative analysis. |