I see this all the time in behavioral health research, and typically these studies are underpowered—they’re just trying to say “me too” so they can get reimbursed for their own particular brand of services. When I train my staff on these concepts, I use graphics to show the lines Andy describes below.
Teresa Benson, M.A.
Licensed Psychologist
Sr. Clinical Information Specialist
McKesson Health Solutions
Prior Lake, MN 55372
From: Evidence based health (EBH) [mailto:[log in to unmask]] On Behalf Of Andy Hutchinson
Sent: Wednesday, January 18, 2012 11:47 AM
To: [log in to unmask]
Subject: Re: Query re non-inferiority studies
And of course, the opposite of non-inferior is not ‘inferior’ but ‘not non-inferior’. So something can be
· non-inferior but inferior (CIs are less than line of no difference and don’t cross it, but don’t cross non-inferiority margin)
· non-inferior but not inferior (CIs cross line of no difference, but don’t cross non-inferiority margin)
· not non-inferior but not inferior (CIs cross line of no difference and cross non-inferiority margin)
confusing? I find it hard enough as a native English speaker. Hats off to anyone thinking about this if English isn’t their first language.
Andy
Andy Hutchinson MEd, Pharmacist
Education and Development Manager
National Prescribing Centre
Provided by the National Institute for Health and Clinical Excellence
Ground Floor Building 2000 | Vortex Court | Enterprise Way | Wavertree Technology Park | Liverpool L13 1FB
Tel: 07824 604962
Web: www.npc.nhs.uk
email: [log in to unmask]">[log in to unmask]
NICE Annual Conference 2012, 15-16 May, Birmingham, UK
Disclaimer: This e-mail may contain confidential and/or proprietary information some or all of which may be legally privileged. It is for the intended recipient only. If any addressing or transmission error has misdirected this e-mail, please notify the author by replying to this e-mail and destroy any copies. If you are not the intended recipient you must not use, disclose, distribute, copy, print or rely on this e-mail
From: Evidence based health (EBH) [mailto:[log in to unmask]] On Behalf Of William Grant
Sent: 18 January 2012 16:37
To: [log in to unmask]
Subject: Re: Query re non-inferiority studies
Hi
Steve is correct. It is possible to show non-inferiority but not show superiority.
The problem is that most folks don't care about non-inferiority, superiority is
much more 'media friendly'
Many studies touted and designed as NI and implemented with the assumptions
of a NI trial are then reported as superiority studies. It often takes some
dissection of the article to really understand what happened.
An eminently readable introduction to NI trials and the statistics behind them
can be found in the US FDA's
Guidance for Industry: Non-inferiority Clinical Trials found at (and free):
Others are likely to have other suggested resources
Bill
William D. Grant, EdD
Associate Dean, Graduate Medical Education
Professor, Emergency Medicine
Professor, Family Medicine
SUNY Upstate Medical University
750 E. Adams St. EmStat
Syracuse, NY 13210
315-464-4861 (p) 315-464-4854 (f)
STATEMENT OF CONFIDENTIALITY
The information contained in this electronic message and any attachments to the message are intended for the exclusive use of the addressee(s) and may contain confidential or privileged information that is protected by law. If you are not the intended recipient, please notify the sender at (315) 464-6997 or at [log in to unmask], and destroy all copies of this message and any attachments. This communication may not be forwarded without the express written permission of the original author.
>>> Steve Edwards <[log in to unmask]> 1/18/2012 11:12 AM >>>
Hi Roy,
It can be quite confusing!
You are right in most cases that a non-inferiority trial is likely to
demonstrate no clinically meaningful differences between the interventions
compared (if it meets its primary outcome).
However, a non-inferiority design does not preclude the possibility of one
intervention being superior to another. In a sense a non-inferiority study
is an "over powered" superiority study.
One thing to be careful of is that non-inferiority is based on per protocol
results (to prevent attrition bias) while superiority should be based on an
intention-to-treat analysis.
I hope that helps.
Best wishes,
Steve
_______________________________________
Dr Steven J. Edwards DPhil MSc BSc (Hons)
Head of Health Technology Assessment
BMJ Technology Assessment Group (BMJ-TAG)
BMJ Evidence Centre
BMJ Group, BMA House
Tavistock Square
London WC1H 9JR
Tel: +44 (0) 207 383 6112
Mob: +44 (0) 776 823 7218
Fax: +44 (0) 207 383 6242
Email: [log in to unmask]
BMJ Evidence Centre: http://evidencecentre.bmj.com
BMJ Group: http://group.bmj.com
From:Marsh Roy <[log in to unmask]>
To:[log in to unmask]
Date:18/01/2012 16:05
Subject:Query re non-inferiority studies
Sent by:"Evidence based health (EBH)"
<[log in to unmask]>
This question was posed to me by a public health information analyst the
other day
"Can you work out NNT in a non-inferiority trial?'
I think not. Because the finding is equivalence. So you can't do it (can
you?)
But I have come across trials that call themselves 'non-inferiority' but
clearly show superiority, at least for some outcomes. And work out NNT for
those outcomes (though not for the equivalent outcomes).
Presumably the trials had to demonstrate that they were powered enough to
detect superiority ... and then went and found it (even though that wasn't
the actual aim)?
Why call themselves 'non-inferiority' anyway, if they have to be as
powerful as 'normal' trials? What does 'non-inferiority' add to my
understanding of a trial?
example: Diggle L, Deeks JJ, Pollard AJ. Effect of needle size on
immunogenicity and reactogenicity of vaccines in infants: randomised
controlled trial. BMJ 2006;333:571.
http://www.bmj.com/content/333/7568/571
I bow before greater minds. Especially if the answer is simple.
Roy Marsh, Research Fellow
Evidence Adoption Centre
Douglas House, 18 Trumpington Road, Cambridge, CB2 8AH
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please visit http://www.symanteccloud.com
______________________________________________________________________
_______________________________________________________________________
The BMJ Group is one of the world's most trusted providers of medical information for doctors, researchers, health care workers and patients group.bmj.com. This email and any attachments are confidential. If you have received this email in error, please delete it and kindly notify us. If the email contains personal views then the BMJ Group accepts no responsibility for these statements. The recipient should check this email and attachments for viruses because the BMJ Group accepts no liability for any damage caused by viruses. Emails sent or received by the BMJ Group may be monitored for size, traffic, distribution and content. BMJ Publishing Group Limited trading as BMJ Group. A private limited company, registered in England and Wales under registration number 03102371. Registered office: BMA House, Tavistock Square, London WC1H 9JR, UK.
_______________________________________________________________________
__________________________
Delivered via MessageLabs
__________________________
The information contained in this message and any attachments is intended for the addressee(s) only. If you are not the addressee, you may not disclose, reproduce or distribute this message. If you have received this message in error, please advise the sender and delete it from your system. Any personal data sent in reply to this message will be used in accordance with provisions of the Data Protection Act 1998 and only for the purposes of the Institute's work.
All messages sent by NICE are checked for viruses, but we recommend that you carry out your own checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses.
http://www.nice.org.uk