Neil - the relevant question is probably at what absolute risk of CVD is
treatment justified rather than at what age, although age and risk are
highly correlated. There is no simple answer as it also depends on the
cost of the intervention, the resources available, and the patient's
preferences. In NZ we have spent alot of time discussing this and our
current advise is that in patients with a 10-15% 5 year CVD risk (therefore
5 yr NNT to prevent a CVD event is about 25) it is useful to discuss the
possibility of initiating treatment - see my previous email to the list
regarding our justification for this. Your point about the time and effort
required to monitor and treat low risk people (rather than mild
hypertension which can be associated with high risk in patients with
multiple other risk factors) is a very important one. Low risk people
require infrequent monitoring and are unlikely to require drug treatment.
A patient in their 20s and 30s probably only needs one bp measurement every
5-10 years, and in their 40s and 50s probably only once every 3-5 yrs
unless they have other risk factors which put them at high risk. When
asking the question, how often should I evaluate this patient, you should
ask yourself what degree of change in a risk factor would lead me to
initiate or change my current management of this patient? Then you need to
guestimate the time it would take for a risk factor like bp or cholesterol
to change by a clinically relevant amount and have a surveillance programme
which will capture this. If you add up all the time you or your staff
measure bp unecessarily (and lipids), you could probably do alot of other
worthwhile things - like measure bp and lipids and treat high risk people.
Rod
>In a message dated 3/9/99 4:57:15 GMT Standard Time, [log in to unmask]
>writes:
>
><< I am saying that the difference in absolute risk between the
> early and late treated hypertensives will be very small and so the NNT very
> large. The evidence comes from comparing the effect of treatment in RCTs
> compared with the estimated difference in risk in cohort studies. What we
> find is that the predicted effect of lonterm differences in risk from
> cohort studies is very similar to the actual effects observed in trials. >>
>
>At what age does tratment become justifiable or do we wait until>60 or is
>there a sliding scale of NNT's for treating mild hypertension. I've been
>puzzling this issue for a while as the monitoring/ treatment of milld
>hypertension has huge workload implications in primary care which may distract
>us from more important issues ie secondary prevention but BHS emanations soon
>bring me back into line even though the NNT's are not very compelling.
>Neil Upton
Dr Rodney Jackson MBChB PhD FAFPHM
Associate Professor of Epidemiology
Head of Department
Dpt of Community Health, School of Medicine
University of Auckland
(Grafton Mews, 52-54 Grafton Rd)
Private Bag 92019, Auckland, New Zealand
Phone: +64 (0)9-3737599 ext 6343
Fax: +64 (0)9-3737503
e-mail: [log in to unmask]
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