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Table 1 Four different ways of expressing the effect of preventive cholesterol-lowering therapy to a hypercholesterolaemic person

From: Impact of effectiveness information format on patient choice of therapy and satisfaction with decisions about chronic disease medication: the "Influence of intervention Methodologies on Patient Choice of Therapy (IMPACT)" cluster-randomised trial in general practice

Format Examples of ways of expression
RRR If a person with high cholesterol level like you takes the medicine, the risk of dying from a heart attack will be reduced by 33% within the next 10 years
ARR If people with high cholesterol level like you do not take the medicine on average 15 out of 100 people, 15%, will die of a heart attack within the next 10 years. However, if people take the medicine on average 10 out of 100, 10%, will die of a heart attack over the next 10 years. That means that on average 5% fewer persons will die
NNT If 20 people with high cholesterol level like you take the medicine, there will on average be one more alive after 10 years than if they do not take the medicine
POL If people with high cholesterol level like you take the medicine, for the rest of their lives they will on average live 8 months longer than if they do not take medicine