Letters Drug prevention of hypertension

Authors’ reply

BMJ 2009; 338 doi: https://doi.org/10.1136/bmj.b2602 (Published 29 June 2009) Cite this as: BMJ 2009;338:b2602
  1. Malcolm Law, professor of epidemiology and preventive medicine1,
  2. Joan K Morris, professor of medical statistics1,
  3. Nicholas Wald, professor of epidemiology and preventive medicine1
  1. 1Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine, Queen Mary, University of London, London EC1M 6BQ
  1. m.r.law{at}qmul.ac.uk

    Our analysis of randomised trials showed that cardiovascular risk decreases with blood pressure down to 110 mm Hg systolic,1 below which, as Lewis states (BMJ 2009;338:b2596, doi:10.1136/bmj.b2596), there is a lack of data. But systolic blood pressure exceeds 110 mm Hg in 99% of people over 55,2 after allowing for regression to the mean.3 Three drugs at half standard dose would lower systolic pressure from 110 to 100 mm Hg,1 and such blood pressures are not unusual in youth,2 with no untoward effect.

    Absolute risk should determine the indication for blood pressure lowering drugs, as Bower states (BMJ 2009;338:b2597, doi:10.1136/bmj.b2597), but this depends more on age than blood pressure. The average risk of a coronary heart disease event or stroke in the next 10 years is about 8% in a 55 year old untreated man, 15% at 65, and 31% at 75.4 5 People over 55 are at high risk simply on account of their age. Schachter states that with systolic blood pressure 135 mm Hg risk is too low to justify treatment (BMJ 2009;338:b2601, doi:10.1136/bmj.b2601), but at age 75 it is the same as at age 65 with systolic pressure 170 mm Hg.3 Low dose combination treatment is unlikely to cause symptoms in more than about one person in 20.6

    Glaser’s division of society into hypertensive and normotensive (BMJ 2009;338:b2598, doi:10.1136/bmj.b2598) is an artificial dichotomy which ignores the fact that reducing blood pressure from any level in adults reduces risk.1 Offering treatment to all above a specified age regardless of blood pressure does not “medicalise” people because they do not become “patients” with a medical diagnosis, but telling people they have “hypertension” does medicalise them.

    Contrary to Bangalore and Messerli’s statement (BMJ 2009;338:b2600, doi:10.1136/bmj.b2600), we showed (not assumed) that different classes of drug at standard dose reduce blood pressure to a similar extent,6 that blood pressure reduction depends on pretreatment level,1 and that the trials show a greater effect of calcium channel blockers and a smaller effect of β blockers in preventing stroke.1 They believe that the variations in design and setting between trials were weaknesses. In fact the variations were essential: without them it could not have been shown that the proportional reductions in disease events is independent of blood pressure and independent of the presence or absence of cardiovascular disease.

    It is now accepted that statins prevent coronary heart disease events and ischaemic strokes regardless of pretreatment cholesterol. The same approach needs to apply to blood pressure reduction, which prevents coronary heart disease events and stroke regardless of pretreatment blood pressure.

    Notes

    Cite this as: BMJ 2009;338:b2602

    Footnotes

    • Competing interests: ML and NW hold patents (granted and pending) on the formulation of a combined pill to simultaneously reduce four cardiovascular risk factors, including blood pressure.

    References

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