Characteristics of included studies
| Study | Participants: sample size (response rate%); age; women (%); data collection | Participants characteristics settings | Scenario: risk; medication; adverse event; side effects; cost | Outcomes |
| Carling et al, internet based 46 | 770 participants; 62% between 40–59 years; 58% women; internet-based survey (in English) | Community (18+; internet users); 90% educated to more than 12 years; 84% from USA; 23% GP or health professionals; | Hypothetical; single-choice experiment; high cholesterol level; daily statin-like; 10-year CV risk of angina or heart attack; side effects of statins; US$50 per month | To decide whether to take the medication based on a single value of risk reduction (ARR or NNT) |
| Carling et al, internet based 29 | 2978 participants; 54% between 40–59 years; 59% women; internet-based survey (in English and Norwegian) | Community (18+; internet users); 91% educated to more than 12 years; 42% from USA | Hypothetical; single-choice experiment; high cholesterol level; daily statin-like; 10-year CV risk of angina or heart attack; side effects of statins; US$50 per month | To decide whether to take the medication based on a single value of risk reduction (ARR or NNT) |
| Carling et al, internet based 26 | 1528 participants; 49% between 40–59 years; 53% women; internet-based survey (in Norwegian) | Community (18+; internet users); 59% educated to university level | Hypothetical; single-choice experiment; 40 years old, non-smoker, active and has a healthy diet; high blood pressure level; daily; 10-year CV risk of stroke or heart attack; dizziness, impotence nausea, muscle cramps and others; copayment | To decide whether to take the medication based on a single value of risk reduction, framed both positively and negatively (ARR) |
| Dahl et al, Denmark 34 | 1367 participants (50%); mean age 60; 52% women; in-person interview | Community (40+); 32% had elementary education only; 5% history of heart attack and 18% hypercholesterolaemia | Hypothetical; single-choice experiment; high cholesterol level; daily; heart attack; few and harmless side effects; 60€ per year | To decide whether to take the medication based on a single value of risk reduction (POL) |
| Fontana et al, UK 10 | 360 participants; mean age 38 years; 50% women; face-to-face interview | Community; 22% on regular medications; 1% history of previous CVD | Hypothetical; trade-off; high cholesterol level; daily statin-like; CVD and death; no side effects; negligible | Medical aversion (gain in lifespan required by participants to commence lifelong therapy); result was extracted from figure 1 |
| Fried et al, USA 30 | 356 participants; mean age 76; 75% women; in-person interview | Community (senior centres); mean years of education was 13; 69% had more than three chronic conditions; 92% took one or more medication, with a mean of 4 | Hypothetical; single-choice experiment; multiple scenarios; primary CVD prevention; daily; 5-year MI risk; no side effects; covered by insurance | To decide whether to take the medication based on a single value of risk reduction (ARR) + pictograph |
| Goodyear-Smith et al, New Zealand 27 | 100 participants (53%); mean 66 years; 60% women; telephone interview | Outpatients (four family practices); patients eligible if they had heart disease and on statin | Hypothetical; single-choice experiment; angina or heart attack; daily statin-like; 5-year heart attack risk; few side effects; | To decide whether to take the medication based on a single value of risk reduction (ARR or NNT); negative framing |
| Halvorsen and Kristiansen, Norway 36 | 1201 participants (60%); 43% between 25–44 year; 48% women; face-to-face (or telephone) interview | Community; 28% educated more than 12 years; 11% history of hypertension, 8% hypercholesterolaemia | Hypothetical; multiple-choice experiment; multiple scenarios; angina or heart attack; daily statin-like; heart attack or stroke; no serious side effects; cost comparable with common cardio-preventive medication | To decide whether to take the medication based on a single value of risk reduction (3-year NNT) |
| Halvorsen et al, Norway 19 | 1397 participants (81%); mean 58 years; 34% women; mailed questionnaire | Community; 23% educated more than 12 years; 21% previous CVD history | Hypothetical; single-choice experiment; daily statin-like; heart attack; neither common nor dangerous side effects; refunded | To decide whether to take the medication based on a single value of risk reduction (5-year NNT, POL) |
| Hudson et al, New Zealand 3 | 354 participants (36%); mean 60 years; 44% women; mailed questionnaire | Outpatients (three GPs, all registered 50–70 years); 31% educated to high school only; 13% previous CVD history | Hypothetical; single-choice experiment; daily; death; no major side effects; S3 per 3 months | To choose, from six different estimates (10-year NNT), the number of lives should be saved to justify lifelong medication |
| Hux and Naylor, Canada 9 | 100 participants; 53% older than 55 years; 47% women; questionnaire | Outpatients (35–65 years); 55% take cardiovascular medications; 70% history of heart disease; 62% attended cardiology clinic | Hypothetical; multiple choice experiment; daily statin-like; heart attack; negligible side effects; insured | To decide whether to take the medication based on a single value of risk reduction (5-year ARR, NNT, POL) |
| Kristiansen et al, Denmark 35 | 675 participants (60%); mean age 44 years; 51% women; face-to-face interview | Community; 21% educated to elementary-level only; 3.3% previous CVD history | Hypothetical; single-choice experiment; daily; heart attack; few and mild side effects; copayment $55 per year | To decide whether to take the medication based on a single value of risk reduction (3-year NNT) |
| Leaman and Jackson, UK 47 | 216 participants (41%); 40.5% between 50–69 years; 55% women; mailed questionnaire | Outpatients (single GP); the mean age at which respondents finished education was 16.7 years; 13% on antihypertensive medication; 2% previous MI | Hypothetical; iterative process; antihypertensive daily; heart attack; some side effects; some payment | To choose, from six different estimates (5-year NNT), the number of lives should be saved to justify lifelong medication; negative framing |
| Marshall et al, UK 48 | 203 participants; median age 65; 13% women; face-to-face interview | Outpatients (13 practices, no CVD history); mean years of education 15.5; 34.5% on long-term oral medications; 50% had less than 7.5% 5-year coronary risk | Hypothetical; multiple-choice experiment; daily; heart disease; rare side effects; | To decide whether to take the medication based on a single value of risk reduction (5-year ARR); each participant was presented with six scenarios. |
| McAlister et al, Canada 32 | 74 participants (51%); mean age 49; 53% women; face-to-face interview | Outpatients (five GPs and four internists, mild hypertension; no overt CVD); 69% educated to more than 12 years; 65% on antihypertensive | Hypothetical; multiple-choice experiment; multiple scenarios; antihypertensive daily; death, MI, stroke; | Iterative process to achieve the smallest benefit (ARR) that justify lifelong medication (MCID) |
| Misselbrook and Armstrong, UK 31 | 309 participants (102 hypertensive, 207 normotensive) (89%); aged 35–65 years; mailed questionnaire | Outpatients (single practice); patients excluded if illiterate, CVD, diabetes, disability or mental illness | Hypothetical; single-choice experiment; antihypertensive-like daily; stroke | To decide whether to take the medication based on a single value of risk reduction (ARR, NNT) |
| Nexøe et al, Denmark 37 | 2326 participants (50%); mean age 47 years; 56% women; face-to-face interview | Community; 26% educated to elementary level | Hypothetical; single-choice experiment; multiple scenarios; daily; death or heart attack; out of pocket payment | To decide whether to take the medication based on a single value of risk reduction (NNT) |
| Nicholson et al, UK 49 | 384 participants (53%); mailed questionnaire | Outpatients (one GP) | Hypothetical; single-choice experiment; statin-like daily; MI | To choose, from four different estimates (5-year NNT), the number of lives should be saved to justify lifelong medication |
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Sorensen et al, Denmark 50 | 1519 participants (49%); mean age 59; 53.9% women; face-to-face interview | Community; 6% previous heart attack; 17% hypercholesterolaemia | Hypothetical; single-choice experiment; daily; death or heart attack; mild and harmless side effects; 45€ per year | To decide whether to take the medication based on a single value of risk reduction (3-year RRR with baseline risk) |
| Steel, UK 38 | 58 participants (58%); 45% 41–65 years old; 58% women | Community (39 practices) | Single-choice experiment; antihypertensive medication | To choose from a five different estimates (5-year NNT), the number of lives should be saved to justify lifelong medication |
| Stovring et al, Denmark 28 | 1169 participants (37%); aged 40–59; 57% women; face-to-face interview | Community; median years of education 13 years; 37% CVD history | Hypothetical; single-choice experiment; multiple scenarios; statin-like daily; fatal heart disease; out of pocket | To decide whether to take the medication based on a single value of risk reduction (10-year ARR, NNT, POL) |
| Trewby et al, US 33 | 307 participants (97%); mean age 61 years; 42% women; face-to-face (or telephone) interview | Both (three groups1: discharged from CCU2; no MI history but on medication,3 neither history nor medication) | Hypothetical; single-choice experiment; statin-like daily; heart attack; safe | Iterative process to achieve the minimum threshold (POL) that justify lifelong medication; extracted from figure 3 |
ARR, absolute risk reduction; CV, cardiovascular; CVD, cardiovascular disease; GP, general practitioner; MI, myocardial infarction; NNT, number needed to treat; POL, prolongation of life.