Table 1 Overview of constructs, conceptual definitions, items, and answering options

Perceived susceptibility: the individual's belief of the chance of contracting a certain disease/condition

1. According to you, what are the chances that you will develop elevated cholesterol levels? Answering options: 1 = very low - 5 = very high

2. According to you, what are the chances that you will develop elevated cholesterol levels compared to others of your age and gender? Answering options: 1 = much smaller - 5 = much larger

Perceived severity: the individual's belief of the seriousness of a certain disease/condition

1. According to you, how severe is an elevated cholesterol level? Answering options: 1 = not severe at all - 5 = very severe

Cues to action: bodily or environmental events that trigger action such as education, symptoms, media

1. Do you or someone in your immediate environment have elevated cholesterol levels? Answering options: 0 = no, 1 = yes

Perceived benefits: the individual's belief that a certain action will effectively reduce the disease threat

1. According to me, performing a self-test is important

2. Self-testing means taking responsibility for your own health

3. Self-testing provides a sense of security about your own health

4. An important advantage of this self-test is a fast result

5. An important advantage of this self-test is privacy

6. An important advantage of this self-test is that it saves time

7. By testing myself, I can reassure myself

8. By testing myself I take care of my own health

9. It feels good to take responsibility for my own health

Perceived barriers: the individual's belief about the negative aspects/costs of a specific health action

1. The costs of this self-test are a barrier to me

2. Testing myself would make me too concerned with my health

3. Being (too) much concerned with my health scares me

4. Just thinking about self-testing scares me

5. Just thinking about self-testing makes me insecure

Self-efficacy: the individual's confidence in one's capability to successfully perform a certain action (Recoded: 1 = completely agree - 5 = completely disagree)

1. Performing this self-test is difficult

2. When performing this self-test I would miss professional assistance

3. When interpreting the test result I would miss professional assistance

Subjective norm: the individual's belief that a certain individual or group support or reject performing that specific action

1. My partner (or others in my immediate environment) expects me to perform this self-test

Anticipated regret: the individual's fear of the feeling of regret if a certain action is not performed

1. I would regret it if I didn't perform this self-test and it subsequently appeared that I have an elevated cholesterol level.

Moral obligation: the individual's belief of being morally obliged to perform that action

1. I perceive it as a moral obligation to myself to perform this self-test

2. I perceive it as a moral obligation to the people around me to perform this self-test

Response efficacy: the individual's belief in the effectiveness of a response to control the risk of a certain disease/condition

1. The result of this self-test is reliable

2. If the test result is normal (nothing's the matter), you can be sure that this result is correct

3. If the test result is abnormal (something's the matter), you can be sure that this result is correct

4. If the test result indicates that something's the matter, I'm able to take the correct subsequent action