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Serum cholesterol, haemorrhagic stroke, ischaemic stroke, and myocardial infarction: Korean national health system prospective cohort study

BMJ 2006; 333 doi: https://doi.org/10.1136/bmj.38855.610324.80 (Published 29 June 2006) Cite this as: BMJ 2006;333:22

Cholesterol, stroke, and age

Ebrahim and colleagues report whether levels of blood cholesterol are
predictive for haemorrhagic and ischaemic stroke in a large cohort of
young- and middle-aged Korean civil servants [1]. They found that low
levels of cholesterol were associated with haemorrhagic stroke while high
levels of cholesterol were associated with ischaemic stroke.

Incidence of stroke rises sharply with increasing age. The
overwhelming majority of all strokes occur in subjects aged 70 years and
over. The mean age of the participants in this study was about 42 years
(SD 9 years). This means that 95% of study participants was under 60 years
at baseline and therefore under 70 at end of follow up. This is important
since the predictive value of total cholesterol for cardiovascular
mortality is heavily dependent on age. After age 70 there appears to be no
association with cardiovascular mortality [2] while after age 80 high
total cholesterol might even be beneficial [3,4]. A similar pattern with
age probably also holds for cholesterol and risk of stroke [5].

We agree with the authors that “…the burden of stroke is becoming
greater as the population ages, making its prevention a priority”.
However, in this case it is not possible to simply transpose the findings
from young- and middle-aged people to the elderly population at risk.
Therefore, the study by Ebrahim et al does not contribute significant
knowledge whether total cholesterol is a risk factor for the vast majority
of strokes.

Anton JM de Craen,
Gerard J Blauw,
Rudi GJ Westendorp.
Department of Gerontology and Geriatrics,
Leiden University Medical Centre.

(1) Ebrahim S, Sung J, Song YM, Ferrer RL, Lwalor DA, Davey Smith G.
Serum cholesterol, haemorrhagic stroke, ischaemic stroke, and myocardial
infarction: Korean national health system prospective cohort study. BMJ
2006;333:22-27.

(2) Shipley MJ, Pocock SJ, Marmot MG. Does plasma cholesterol
concentration predict mortality from coronary heart disease in elderly
people? 18 year follow up in Whitehall study. BMJ 1991;303:89-92.

(3) Weverling-Rijnsburger AWE, Blauw GJ, Lagaay AM, Knook DL,
Meinders AE, Westendorp RGJ. Total cholesterol and risk of mortality in
the oldest old. Lancet 1997;350:1119-1123.

(4) Schatz IJ, Masaki K, Yano K, Chen R, Rodriguez BL, Curb JD.
Cholesterol and all-cause mortality in elderly people from the Honolulu
Heart Program: a cohort study. Lancet 2001;358:351–355.

(5) Simons LA, Simons J, Friedlander Y, McCallum J. Cholesterol and
other lipids predict coronary heart disease and ischaemic stroke in the
elderly, but only in those below 70 years. Atherosclerosis 2001;159:201-
208.

Competing interests:
None declared

Competing interests: No competing interests

04 July 2006
Anton J.M. de Craen
epidemiologist
Gerard J. Blauw and Rudi G.J. Westendorp
Leiden, 2300 RC, The Netherlands