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EVIDENCE-BASED-HEALTH  December 2005

EVIDENCE-BASED-HEALTH December 2005

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Subject:

Re: Using CEBM's Levels of Evidence to rate linkages between animal and human health

From:

Paul Glasziou <[log in to unmask]>

Reply-To:

Paul Glasziou <[log in to unmask]>

Date:

Wed, 7 Dec 2005 15:59:38 +0000

Content-Type:

text/plain

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Parts/Attachments

text/plain (230 lines)

Dear All,
There may be some clash between philosophy and practicality here. A 
main reason for the hierarchy is as a *search* strategy in real time: 
how do I find the best current evidence in a few minutes because of a 
patient I am seeing *now*?
A. An up to date systematic review can give me that (Level 1),
B. ... but if no one has done that then what is the best & largest 
single trial? (level 2)
C. ... and if there are no trials, then is there a good cohort study, 
etc (level 3)

There is no way I can find, assess, and synthesize all the available 
evidence in real time (ie minutes or at least the same day). A 
systematic review of trials might take 3-6 months, and the patient 
gone (or worse, dead). And a review that covered all possibly 
relevant evidence (cohort, animal, etc) would take even longer.

Of course it would be lovely to synthesise and compare across all 
types of evidence. That's great for PhD's and critical reviews. But 
its impractical for daily patient care, where I will have a dozen 
questions a day.  Given this practical purpose, maybe we need one 
hierarchy for clinicians and another for researchers? We certainly 
need to recognise the different purposes and timescales. The current 
CEBM Levels is written with the daily answering of questions in mind,

Best wishes,


Paul Glasziou




At 07/12/2005, Noertjojo, Kukuh wrote:

>Dear All.
>To follow up on my previous e-mail, please find below some 
>suggestions that Dr. Shrier proposed. Hopefully this suggestion can 
>provide further enlightenment to all of us.
>
>Thank you to Dr. Shrier for his contribution.
>Sincerely,
>Kukuh
>From: Ian Shrier [<mailto:[log in to unmask]>mailto:[log in to unmask]]
>Sent: Tuesday, December 06, 2005 2:12 PM
>To: Noertjojo, Kukuh
>Subject: RE: Using CEBM's Levels of Evidence to rate linkages 
>between animal and human health
>
>Kukoh
>Please forward this to your group.
>I agree with Dr. Johnston's comments and the efforts everyone is 
>making towards trying to use all the evidence. I am not personally 
>in favor of establishing any a priori heirarchy because some people 
>will then apply the heirarchy without evaluating the individual circumstances.
>
>Basically, my philosophy is that we should be able to explain the 
>discrepancies between any pieces of evidence. Sometimes these are 
>due to biases or chance, but othertimes due to differences in 
>patient characteristics, etc. In the case of RCTs vs Observational 
>studies in humans, many people simply say the reason is study design 
>(if there is a difference) without evaluating other factors.
>
>The same is true for animal evidence and the principle I follow is 
>the same. Certainly one has to understand the animal model and 
>ensure it mimics the human model, which it doesn't always. One of 
>the criticisms for animal models is the DES story. I don't think 
>this is a fair comparison. Prior to DES, no one thought that the 
>side effects of a drug could occur in the offspring when the 
>offspring becomes an adult. So no one would have looked for this.
>
>In the end, heirarchy can be based on either relevance or subject to 
>bias. Both of these can be evaluated for each study examined but I 
>don't see the utility in trying to combine them into one category. 
>The current heirarchy system seems to be based on more on the 
>complexity of evaluating the study rather than on the study 
>bias/relevance itself. This is not an optimal approach.
>
>Hope this helps further your discussion
>Ian Shrier MD, PhD, Dip Sport Med, FACSM
>Past-president, Canadian Academy of Sport Medicine
>check out: <file://www.casm-acms.org>www.casm-acms.org
>
>Centre for Clinical Epidemiology and Community Studies
>SMBD-Jewish General Hospital
>3755 Cote Ste-Catherine Rd
>Montreal, Qc H3T 1E2
>Tel: 514-340-8222 ext 7563
>Fax: 514-340-7564
>-----Original Message----- From: Noertjojo, Kukuh 
>[<mailto:[log in to unmask]>mailto:[log in to unmask]] 
>Sent: 05-Dec-2005 2:23 PM To: [log in to unmask] Subject: Using 
>CEBM's Levels of Evidence to rate linkages between animal and human 
>health Dear Ian,  Thank you very much for the thought provoking 
>talked you gave us last Saturday. You mentioned about using all 
>available evidence (including animal studies) in providing answers. 
>I was wondering if you can provide some lights to our discussion 
>group regarding the linkage between animal and human health discussion below.
>
>If you may, please answer directly to the group e-mail server below 
>or please forward it to me and then I'll forward it to the group. 
>Thank you so much Ian, I am looking forward to read your comments. 
>Sincerely, Kukuh  -----Original Message----- From: Noertjojo, Kukuh 
>Sent: Monday, December 05, 2005 10:46 AM To: 'Olive Goddard'; 
>[log in to unmask] Subject: RE: Using CEBM's 
>Levels of Evidence to rate linkages between animal and human 
>health  Dear All. The Effective Practice and Organization of Care 
>Group of Cochrane 
>(<http://www.epoc.uottawa.ca/aboutus.htm>http://www.epoc.uottawa.ca/aboutus.htm) 
>may be a good place to start looking for info. This Cochrane Review 
>Group certainly consider before-after and interrupted time series as 
>source of evidence.
>
>At a recent Cochrane meeting I attended a thought provoking talked 
>by Dr. Ian Shrier on the validity of different inclusion criteria 
>for systematic reviews, I am forwarding this e-mail to him and 
>hopefully he can give us an important input. Thank you. Kukuh  Kukuh 
>Noertjojo, MD MHSc MSc Evidence Based Practice Group, Clinical 
>Services, Worker and Employer Services WorkSafe BC 6951 Westminster 
>Highway Richmond, BC V7C 1C6 CANADA.  Phone: 604 231 8417 Fax: 604 
>279 7698  -----Original Message----- From: Evidence based health 
>(EBH) 
>[<mailto:[log in to unmask]>mailto:[log in to unmask]] 
>On Behalf Of Olive Goddard Sent: Thursday, December 01, 2005 2:23 AM 
>To: [log in to unmask] Subject: Re: Using CEBM's 
>Levels of Evidence to rate linkages between animal and human 
>health  Dear Colleagues,  Does anyone have any comments on the 
>following.  All good wishes,  Olive  Olive Goddard Centre and 
>Editorial Manager Centre for Evidence-Based Medicine Room 116 
>Institute of Health Sciences Old Road Campus, Headington Oxford, OX3 
>7LF 
>..................................................................... 
>  Tel: +44 (0)1865 226991 email: [log in to unmask] Fax: +44 
>(0)1865 226845 web: <file://www.cebm.net>www.cebm.net Mobile: 0773 
>484 2403 web: <file://www.cebmh.com>www.cebmh.com  >>> "Mark 
>Johnston" <[log in to unmask]> 11/29/05 3:35 pm >>> Here are some 
>observations which may serve to stimulate further discussion, 
>although they are mostly methodological rather than specific to your 
>project.  The study of environmental toxins is an area in which RCTs 
>are not going to be conducted. It is not that the CEBM hierarchy is 
>irrelevant: it is that non-RCT elements need to be examined and 
>strengthened. It seems to me that two sources of evidence would be 
>relevant: i) correlational evidence (in this case on human-animal 
>health associations;  ii) extrapolations from more controlled 
>studies and laboratory studies.  One would expect that theory would 
>be relevant (e.g. animals are similar to humans in some ways but not 
>others). I suspect that it would be better to explicate the theory 
>or alternative theories rather than to ignore the matter. Better 
>studies would test alternative explanations for an association; 
>weaker studies would not.  Time series data become important or 
>critical. If one had good data on human-animal health over time 
>(with a sufficiently large number of points that statistical 
>stability can be established) and f there is a sudden event (e.g. 
>release of a toxin in the environment), then one could in principle 
>detect the effect of the toxin quantitatively. You are probably 
>aware of such designs. Rarely are data sufficient to implement such 
>a study, but if good data were available and alternative 
>explanations ruled out, then convincing (level 1 or 1.5?) or highly 
>probable (level 2?) conclusions could be drawn. In sum, there is a 
>need to augment the standard hierarchy to be more sensitive or 
>explicit regarding correlational and modeling designs, so that one 
>can more precisely distinguish stronger from weaker alternative 
>research designs.  Best regards to all.
>
>Mark V. Johnston, Ph.D. Director of Outcomes Research, KMRREC, 
>Professor, Physical Medicine & Rehabilitation, UMDNJ/NJMS, 1199 
>Pleasant Valley Way, West Orange, NJ 07052 Phone: 973 243 6810 Fax: 
>973 243 6963 R.A.: 973 243 6876  >>> Olive Goddard 
><[log in to unmask]> 11/23/2005 6:39 AM >>> Dear 
>Colleagues,  I posted the following on the EBH list a little while 
>ago. However, the author did not receive any replies, although I am 
>sure several were posted. I have now added Peter Rabinowitz to the 
>EBH list so would be grateful if you would respond again.  As per 
>our policy, I have not attached the manuscript. If you would like a 
>copy would you contact Peter Rabinowitz directly.  All good 
>wishes,  Olive  "Dear Mrs. Goddard,  "I am a faculty member at the 
>Yale University School of Medicine, and a great admirer of the work 
>of your Centre. I am a member of a group engaged in a project funded 
>by the National Library of Medicine to assess the scientific 
>evidence regarding the use of animals as 'sentinels' of human 
>environmental health hazards. Our group of human and animal health 
>professionals are trying to critically determine the strength of 
>evidence linking animal and human health in a number of instances. 
>In recent years, there has been increasing discussion of ways to 
>bridge scientific gaps between animal health and human health 
>professionals. We are trying to build on Evidence Based Medicine 
>principales in this effort, although we realize that it is 
>stretching the concept a bit.  "At the suggestion of Mark Ebell, MD, 
>a physician in the U.S. who has helped develop the S.O.R.T. taxonomy 
>for patient oriented evidence, we have tried to adapt the Centre for 
>Evidence-based Medicine's Levels of Evidence to our task of 
>comparing human and animal health exposure-outcome relationships. 
>The attached draft manuscript gives an example of our approach  "I 
>would be extremely grateful if one or more members of your Centre 
>could give us some feedback on what we are trying to do - does it 
>seem appropriate to try and use the Centre's Levels of Evidence as 
>we are doing in the attached ms? Is there another rating scheme that 
>would fit our needs better - or should we invent our own? Our 
>preference is not to reinvent the wheel, but we also want to respect 
>the scope and purpose of the toods you have developed.  "Any input 
>to our process, no matter how critical, would be greatly 
>appreciated. For further background on our project, please see our 
>website <http://canarydatabase.org>http://canarydatabase.org 
>"Gratefully, Peter Rabinowitz MD MPH Associate Professor Medicine 
>Yale University School of Medicine Yale Occupational and 
>Environmental Medicine Program 135 College Street, 3rd Floor New 
>Haven, CT 06510 Tel 203-785-5885 Fax 203-785-7391 
>[log in to unmask]" Olive Goddard Centre and Editorial 
>Manager Centre for Evidence-Based Medicine Room 116 Institute of 
>Health Sciences Old Road Campus, Headington Oxford, OX3 7LF 
>..................................................................... 
>  Tel: +44 (0)1865 226991 email: [log in to unmask] Fax: +44 
>(0)1865 226845 web: <file://www.cebm.net>www.cebm.net Mobile: 0773 
>484 2403 web: <file://www.cebmh.com>www.cebmh.com
>Kukuh Noertjojo, MD MHSc MSc
>Evidence Based Practice Group,
>Clinical Services, Worker and Employer Services
>WorkSafe BC
>6951 Westminster Highway
>Richmond, BC V7C 1C6
>CANADA.
>
>Phone: 604 231 8417
>Fax: 604 279 7698

Paul Glasziou
Department of Primary Health Care &
Director, Centre for Evidence-Based Practice, Oxford
ph: 44-1865-227055 

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