Intended for healthcare professionals


Hypertension diagnosis should be based on ambulatory blood pressure monitoring, NICE recommends

BMJ 2011; 343 doi: (Published 24 August 2011) Cite this as: BMJ 2011;343:d5421

Ambulatory BP Measurement: there are more cost effective ways of improving diagnosis & monitoring of hypertension

I would like to comment on the NICE recommendation re ambulatory bp
measurement [as reported by Susan Mayor, News, BMJ 343 24.8.11].

There can be no doubt that use of ambulatory blood pressure
measurements would improved the reliability of diagnosis and monitoring of
hypertension. But at a time when as an FTH governor I realise just how
strapped for cash the NHS is, and the impact this has on the medications
likely to be funded for NHS patients, I fear for the consequences of the
switch to routine use of ambulatory measurement, purely because of the
immediate costs, whatever the long term-benefits. Just because someone
drives a Skoda badly it does not mean they need a Ferrari instead.

The main problem with human BP measurement has been the persisting
use of single measurements and the failure to standardise whether or not
they are taken on a working day, am or pm. We have repeatedly advocated
[PJ 2005 274: 121-5; BMJ 2001 323: 805,letters] use of the same technique
which we validated against direct measurements in both anaesthetised and
conscious dogs and showed to be more sensitive than single measurements in
a human [Blood Pressure Monitoring 1996 1: 385-7]: take 6 readings and
discard the first. Eight minutes or less provides a sensitivity which
single readings do not- without the costs of re-equipping every GP

It is extraordinary that the clinical consensus and even journal
referees continue to accept single readings [sometimes three but retaining
the first], of a measurement which, as noted by the first observer to
publish direct readings, Rev Stephen Hales nearly 300 years ago, is
inherently and rapidly variable. "Responses to treatment" in individual
patients measured thus may well reflect nothing more than whether
consecutive checks were on working / non working days, am or pm.

Ambulatory readings are undoubtedly more informative than current
routine practice but at a time of acute financial stringency the crucial
question is whether they are more cost effective than optimising the
existing method at no cost whatever. They are certainly nice, but they may
also unnecessarily expensive.

Competing interests: No competing interests

28 August 2011
Alastair R. Michell
Prof of Comparative Medicine, Univ of London [Barts Hospital, Harvey Inst.]