Francesco P Cappuccio, Pippa Oakeshott, Pasquale Strazzullo, Sally M Kerry
Cappuccio F P, Oakeshott P, Strazzullo P, Kerry S M.
Application of Framingham risk estimates to ethnic minorities in United Kingdom and implications for primary prevention of heart disease in general practice: cross sectional population based study
BMJ 2002; 325 :1271
doi:10.1136/bmj.325.7375.1271
New thresholds for hypertension go beyond the evidence
Sir Cappuccio and colleagues raise an interesting academic point
about the difference in the predicted ratio of cardiovascular disease
(CVD) and coronary heart disease (CHD) in ethnic minorities. Whilst this
may stimulate further epidemiological investigation we believe it
adventurous to base a change in treatment policy for whole populations on
the difference between two mathematical functions derived from the health
of citizens from a single US town with neither African nor South Asian
minorities. The CVD functions have never been adequately validated in
either patient group.
Tools like The Sheffield Table were devised because physicians at the
front line found it difficult to use mathematical functions to estimate
individual risk. They have the advantage of incorporating within 1 simple
paper or software algorithm decisions about antihypertensive drugs and
aspirin for patients with mild hypertension and about statins in those
with hyperlipidaemia. However they only achieve this by simplifications
such as assuming a constant relationship between CVD and CHD risk although
this is known to vary with age, blood pressure and gender. If we are to
introduce different thresholds according to ethnic group then by the same
logic we must adopt different thresholds for each of these factors as
well. In doing so we will lose the simplicity of the tools and re-
introduce a barrier to appropriate prescribing.
Implicit in adopting new thresholds is the assumption that relative risk
reduction offered by all the treatments directed is constant. However
aspirin has little effect on overall stroke incidence, its major benefit
being in preventing CHD [1]. Even worse for haemorrhagic stroke, a
subtype over-represented in one of the groups affected by the suggested
threshold [2], aspirin may increase incidence and at best statins offer
little benefit [3].
Comprehensive current epidemiological data on CHD and CVD is desperately
required including that from ethic minorities to reassure us that our risk
predictions are accurate for all. Until that is to hand we are safer
sticking with the tools already in use.
References
1 Barnett HJM, Taylor DW, Eliasziw M, et al, for the North American
Physicians’ Health Study Research Group. Findings from the aspirin
component of the ongoing physicians health study. N Engl J Med 1988; 318:
262–64.
2 Broderick JP, Brott T, Tomsick T, Huster G, Miller R. The risk of
subarachnoid and intracerebral hemorrhages in blacks as compared with
whites. N Engl J Med 1992;326: 733-6.
3 Heart Protection Study Collaborative Group. MRC/BHF Heart Protection
Study of cholesterol lowering with simvastatin in 20 536 high-risk
individuals: a randomised placebo controlled trial. Lancet 2002;360:7–22.
Competing interests:
PRJ has received fees for speaking on the treatment of hypertension and hyperlipidaemia. He has also been sponsored to attend a number of symposia and his department receives research funding from pharamceutical companies in relation to studies of antihypertensive and lipid lowering drugs.
Competing interests: No competing interests