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Hi all: I thought that medicine A is more beneficial than medicine B? An NNT of 20 in this case would mean "treat 20 people with A rather than B and 1 out of those 20 will benefit in addition to those who usually benefit with B". I think the error has been made because traditionally we look at negative events, e.g. harms rather than benefits and look to see if a particular treatment will reduce rates of harm or death or whatever. Cheers Anne Lethaby ________________________________ From: Evidence based health (EBH) on behalf of Lubna A. Al-Ansary Sent: Mon 20/11/2006 11:39 p.m. To: [log in to unmask] Subject: Re: Fwd: NNT query Hi Olive, Jackie and everyone, In my humble opinion the statement needs to me more explicit to be correct. An NNT of 20 means "treat 20 people with B rather than A and 1 extra patient/person will benefit in addition to those who usually benefit with A". Hope it is clearer this way. Regards, Lubna Olive Goddard <[log in to unmask]> wrote: Dear Colleagues, If anyone is prepared to answer this query I should be grateful if they would respond to Jackie directly. All good wishes, Olive NNT query From: "Stark, Jackie" Date: Thu, 16 Nov 2006 11:30:23 -0000 To: To: *Hello,* *Many years ago I did some courses about EBM which were run by the centre and was told that if there were any queries I could make contact. I have a query about a slide that was presented to nurse prescribers which caused much debate between myself and the presenter. I wonder if someone at the centre would be willing to confirm whether the final statement *i.e treat 20 people with *B rather than A and 1 will benefit* is correct? *My opinion is that, while the calculation of NNT is correct, the drugs should be transposed in the final statement in order for the statement to be correct. The full slide read as follows:* *Medicine A cures 50% of people* *Medicine B cures 45% of people* ** *ARR = 5% ** *RRR = 10% *Number needed to treat (NNT):* ** *the number of people you need to give medicine B rather than medicine A for one to benefit *NNT=100/ARR(%):* ** *In this case 100/5 = 20. ** *i.e. treat 20 people with B rather than A and 1 will benefit. *If you are able to help I would be grateful as most of the audience were completely new to EBM and I feel passionately that they should have the best start possible. I am always mindful and grateful for the excellent introduction provided for me by your centre.* *Best Regards,* Jackie Stark Medicines Management Pharmacist Humber Mental Health Teaching NHS Trust Trust Headquarters Willerby Hill Beverley Road Willerby Hull HU10 6ED Tel: 01482 389202 (Direct) Tel: 01482 301724 (Departmental Secretary) Fax:01482 303927 This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you are not the intended recipient you are notified that any use, disclosure, copying or distribution of the information is prohibited. In such cases, you should destroy this message and kindly notify the sender by reply e-mail. The views expressed in this e-mail and any attachments are personal and, unless stated explicitly, do not represent the view of Humber Mental Health Teaching NHS Trust. As such the Trust will not be bound by this e-mail -- Paul Glasziou Director, Centre for Evidence-Based Medicine, Department of Primary Health Care, University of Oxford www.cebm.net ph +44-1865-227055 fax +44-1865-227036 Dr.Lubna A.Al-Ansary, MSc, FRCGP Associate Professor Dept of Family & Community Medicine College of Medicine, King Saud University P.O.Box 2925, Riyadh 11461 SAUDI ARABIA Email: [log in to unmask]