Intended for healthcare professionals

Rapid response to:

Education And Debate

Risk factor thresholds: their existence under scrutiny

BMJ 2002; 324 doi: (Published 29 June 2002) Cite this as: BMJ 2002;324:1570

Rapid Response:

Pharmacological treatment determined by age alone - a step too far?

EDITOR - Law and Wald(1) provide evidence for the absence of
thresholds in the relationship between risk factor and disease. They
conclude that those with high absolute risk will benefit from risk factor
reduction whatever their initial risk factor level.

They go on to suggest that “in people without cardiovascular disease,
intervention to change risk factors could be introduced when a person's
risk of a disease event over the next few years exceeds a specified value.
Risk could be estimated from age alone or age and sex………individuals at
high risk should receive drug treatment to modify all important reversible
risk factors simultaneously.”

Whilst combination pharmacological cardiovascular risk factor
reduction for the whole elderly population represents an ideal strategy
for the pharmaceutical industry it has a number of limitations as a public
health strategy:

1. By setting an absolute risk threshold for treatment (determined by
age only) the proposed strategy still targets only those at high risk of
disease (the tail of the population distribution curve of risk factors)
and therefore can only have a minimal effect upon the overall burden of
disease in the population.

2. There will be major opportunity costs in treating the whole
elderly population with combination drugs and consequently other
preventative, treatment, care and rehabilitation services for the elderly
would be constrained.

3. The authors’ statement that lower limits of thresholds (such as
blood pressure), beyond which harm will arise, are not reached by current
drug treatment is false - the risks of polypharmacy in the elderly are
significant(2,3) and would be increased

4. Even in the elderly, absolute risk of CHD may not reach 3% per
year without additional risk factors such as smoking and diabetes.
According to the Framingham Coronary Risk Prediction Score(4), a man aged
70-74, total cholesterol 5.18-6.21 mmol/l, HDL 1.17-1.29 mmol/l and blood
pressure (140-159)/(90-99) has an CHD risk of 2.5% per year; for a woman
the risk is only 1.3%.

Targeting people who have had a vascular event or who are diabetic,
with risk factor reduction treatment is an appropriate “high-risk”

The only appropriate strategy, as challenging as it may be, to reduce
the risk of vascular disease in the rest of the population (who cause most
of the burden of disease) is to reduce the average levels of risk factors
in the population, through the promotion of a healthy diet, exercise and
smoking cessation.

Proposals to use drug treatment for primary prevention in the whole
population over a certain age should be resisted.

Steven Laitner
Specialist Registrar, Public Health
National Screening Committee, Institute of Health Sciences,
Old Road, Headington, Oxford OX3 7LF

Competing interests: none

1. Law MR,.Wald NJ. Risk factor thresholds: their existence under
scrutiny. BMJ 1929;324 :1570-6.

2. Beyth RJ,.Shorr RI. Epidemiology of adverse drug reactions in the
elderly by drug class. Drugs & Aging Vol 1999;14:231-9.

3. Malhotra S, Karan RS, Pandhi P, Jain S. Drug related medical
emergencies in the elderly: role of adverse drug reactions and non-
compliance. Postgrad Med J 2001;77:703-7.

4. . 2002.

Competing interests: No competing interests

12 July 2002
Steven M Laitner
Specialist Registrar, Public Health
National Screening Committee, Institute of Health Sciences, Old Road, Headington, Oxford OX3 7LF