Who decides when to start preventive treatment? A questionnaire survey to compare the views of different population subgroups.

Lipid lowering drugs lower the risk of ischaemic cardiovascular events. The absolute benefit is highest in people at greatest risk of having an event in the near future, but adverse effects and costs are similar whatever the baseline risk. The decision to treat entails balancing expected benefits with expected harms, but is essentially a value judgement. Treatment preferences may vary systematically between groups of people either because they have different levels of baseline risk, or because they have different values and priorities. Current UK guidelines recommend treatment for those whose 10 year risk of coronary heart disease is at least 30%. 3 Assuming a relative risk reduction of one third this is an absolute benefit of about 10% over 10 years (or 5% over five years). Very little is known about the level of coronary risk at which either doctors or patients want treatment. One small study suggested that patients and nurses would choose higher risk thresholds (larger absolute benefits) than doctors. The policy to treat a risk of 30% over 10 years is an arbitrary choice. This study compared the absolute benefits of treatment different groups would require before starting treatment themselves.