There is no generic "good" NNT. It is completely dependent on: 1. the
value of the outcome you are trying to modify by treatment; 2. by the NNH
(ie the nummber need to harm) which you have to balance against the NNT; 3.
the costs of the treatments and the harms; and 4. the time period of
treatment, and time to benefit or harm. With respect to quality of life,
these are outcomes which can also be described in terms of NNTs and NNHs
Rod Jackson
>Hello! That's very good question.
>
>I think the NNTs of 2-4 are for therapeutic usage of drugs,and the NNTs
> over 20 are for preventitive usage of drugs.
>i.e. for acute condition,NNTs of 2-4:for chronic condition,NNTs of over 20.
>
>
>> A question I have , is what is a good number for NNT? Bandolier 12
>>indicated that a NNT of 2-4 is suggestive of good NNT ( i.e., ARR of
>>0.25-0.50). However most the the RCT reported in journal s NEJM, Annals
>>etc have statistical significance however their NNT are usually over 20,
>>ie, finasteride for BPH( NNT= 30). I reckon one of the disadvantages of
>>NNT maybe that despite the NNT being over 20 , these patients may have
>>significant improvement in quality of life and other subjective issues.
>>Or is the fact that NNT of 2-4 an over enthusiastic expectation when it
>>comes to a clinical response.I guess in the case of chronic diseases
>>with outcomes occurring over decades a NNT of 50 would be acceptable,
>>however in other more acute conditions one would consider a smaller
>>number for NNT as desirable. Could the members throw some additional
>>light in the defining what is a good number for NNT.
>**********************************************
>Saio,Takeo
>///////////////CHIAKI hospital,JAPAN/////////
>e-mail;[log in to unmask]
>**********************************************
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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