Screening for secondary causes of hyperlipidaemia in general practice

EDITOR, - Screening implies a commitment to appropriate treatment. Philip Evans and Denis Pereira Gray's short paper on the value of screening for secondary causes of hyperlipidaemia raises several issues regarding the diagnosis and correct treatment of hyperlipidaemias.1 In screening for hyperlipidaemia, maximising the efficiency of yield and minimising costs depend on the selection of appropriate tests and the clinical selection of patients. The only initial screening data quoted are cholesterol concentrations, and no data are presented on whether patients were also screened initially for diabetes or thyroid disease, which are relevant to the development of hyperlipidaemia. Even so, the overall yield of disease detected was 20.6% (66/321 patients) with extended secondary screening consisting of measurement of cholesterol concentration, thyroid function profile, and measurement of creatinine and (gamma)- glutamyltransferase. This seems an efficient use of resources.

We have several further concerns with this study. Firstly, the population studied seems to have been heterogeneous, and the cholesterol concentration at which action is necessary would have varied among the population (for example, among women, patients with established vascular disease, and patients with strong family histories); the population also included patients in whom screening for hyperlipidaemia is considered to be of little benefit or controversial (elderly people). Clinically, adding measurement of the triglyceride concentration to screening for hyperlipidaemia has minimal cost implications while identifying patients in whom secondary hyperlipidaemia may occur. However, measurement of the high density lipoprotein cholesterol concentration, which is needed for the correct interpretation of total cholesterol concentrations, adds appreciable extra costs.2,3

Secondly, the authors identified six patients with clinical disease and another six requiring further investigation. Thus the yield from screening was 3.8%. Fifty four of the 321 patients screened, however, had established secondary causes of hyperlipidaemia and were excluded. If known secondary causes are …