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Readers' Points

In Bandolier 5 there was a review of the role of cholesterol screening and the treatment of hypercholesterolaemia. It concluded that screening will not make a contribution to the lowering of overall mortality rates and should be discouraged whilst treatment should be targeted at those patients with the highest overall risk of coronary heart disease. I agree with this, but not with your endorsement of the conclusions of a recently published meta-analysis of cholesterol lowering treatments (Smith, Song & Sheldon, BMJ 1993; 36: 1367-73) which suggested that the likely benefit of treatment was restricted to patients with an annual coronary heart disease mortality rate exceeding 5%.

Implementation of this finding in clinical practice would result in some highly questionable decisions. For instance, lipid lowering drug therapy might be prescribed to men aged more than 80 years since their annual CHD mortality exceeds 3.3%. Drug treatment would be denied to men aged 35-44 years with familial hypercholesterolaemia in whom the annual incidence of fatal coronary heart disease is 1.1%, and the cumulative risk in this condition of a fatal or non fatal myocardial infarction by the age 60 years is about 50%.
The explanation for these anomalous conclusions is that the meta-analysis cited included trials with subjects ranging in age from 18-70 years. Epidemiological principles - and common sense - suggest that the absolute risk of coronary heart disease is unhelpful in determining whether drug treatment is appropriate unless age-specific incidence is taken into account.

Dr Andrew Neil
Radcliffe Infirmary
Oxford




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