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BMJ No 7122 Volume 315 Letters Saturday 13 December 1997 Use of statins See Editorial by Muldoon p 1554 More evidence is needed for guidelines Editor Freemantle et al make some good points about the Standing Medical Advisory Committee's guidelines on the use of statins.(1) Perhaps the weakest point of the guidelines is the statement that patients with peripheral vascular or symptomatic carotid disease have a risk of major coronary events of about 3% a year. Where is the evidence to support this assertion? The authors of the Sheffield tables quote a risk of 4%,(2) citing the UK-TIA (United Kingdom transient ischaemic attack) study.(3) In fact, the event rate was about 3% a year, but a fifth of the patients had existing ischaemic heart disease and the study did not separate these from patients without ischaemic heart disease, who may be at lower risk. The 4% is probably a quote from a study by Heyman et al of 390 patients admitted to hospital with transient ischaemic attack.(4) But 30% of these had angina and 26% had had myocardial infarcts. It is not clear what overall proportion had existing ischaemic heart disease (between 30% and 56%), but again the results did not separate these from patients without prior ischaemic heart disease (although the authors comment that prior ischaemic heart disease was a good predictor of subsequent coronary events). For peripheral vascular disease the Sheffield article cites a study of 67 patients with large vessel peripheral arterial disease.(5) This, however, included only eight people with symptomatic peripheral arterial disease who did not have other cardiovascular disease at baseline. It seems unwise to make generalisations on the basis of a sample of eight. There are many other studies of patients with carotid and peripheral vascular disease that follow up coronary events, but few separate prognosis for those with existing ischaemic heart disease and those without. The risk of a coronary event might well be about 3% a year, but it is probably much lower. That part of the guidelines is based more on eminence than evidence; it would be terrible if attempts to treat patients who might benefit distracted us from treating those who we know will benefit. David Lewis General practitioner Vauxhall Primary Health Care, Liverpool L5 8XR References 1 Freemantle N, Barbour R, Johnson R, Marchment M, Kennedy A. The use of statins: a case of misleading priorities? BMJ 1997;315:826-8. (4 October.) 2 Haq I U, Jackson P R, Yeo W W, Ramsay L E. Sheffield risk and treatment table for cholesterol lowering for primary prevention of coronary heart disease. Lancet 1995;346:1467-71. 3 UK-TIA Study Group. United Kingdom transient ischaemic attack (UK-TM) aspirin trial: interim results. BMJ 1988;296:316-20. 4 Heyman A, Wilkinson W E, Hurwitz B J, Haynes C S, Utley C M, Rosati R A, et al. Risk of ischaemic heart disease in patients with TIA. Neurology 1984;34:626-30. 5 Criqui M H, Langer R D, Fronek A, Feigelson H S, Klauber M R, McCann T J, et al. Mortality over a period of 10 years in patients with peripheral vascular disease. N Engl J Med 1992;326:381-6. Home | Current issue | Past issues | Classified ads | Career Focus | Feedback Collections | About this site | About the BMJ | BMA | Medline