Toby - Yes, 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.
Rod
>In message <C0F01F10DD54D2119CD30060B0680ABC017244A0@exchange_1>, Gary
>Jackson <[log in to unmask]> writes
>>For example, lets take two 35 yr old hypertensive smokers. One we treat
>>with anti-hypertensives, achieving good control. The other we "watchfully
>>wait". Both decline our attempts to stop smoking. Neither became
>>symptomatic. At age 45 we start the 2nd on antihypertensive treatment,
>>achieving like control. My understanding is that at this point their future
>>risks (chance of death/MI etc) are identical? Ie 10 years of presumably
>>extra workload on the heart/blood vessels had no effect on the untreated
>>person? And this means the only point of treating the first for 10 years
>>was the risk reduction you achieved over that 10 year period.
>>
>
>Yes that's the point I was trying to make. Is there evidence to answer
>this question? - and of course if there is a difference in the rate of
>CVD events in patients managed in these two ways say at age 55, then an
>NNT can be calculated. Or is Rod saying that the absolute risk reduction
>will be so small as to make NNT unreasonably high?
>
>Toby
>--
>Toby Lipman 7, Collingwood Terrace, Jesmond, Newcastle upon Tyne. Tel
>0191-2811060 (home), 0191-2437000 (surgery)
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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