Dear Mark - your points are well taken and I agree wholeheartedly
with you. I accept my penicillin example of such a dramatic effect is
rare in real life and used it to mainly to make the methodological
point.
regards Rod Jackson
>The points I have read are well-based and thought out, and I have enjoyed
>reading the discussion.
>
>The example of penicillin is correct and relevant. However, such dramatic
>effects are rare. More often, one reads of researchers who draw unwarranted
>conclusions from case series. I believe that the logic of analysis
>of time series
>designs, particularly multiple interrupted time series, is relevant.
>
>To establish likely causation from time series data, one must establish
>pre-treatment stability on the outcome of interest, and post-intervention
>stability too. Trends should be established, and auto-correlation
>possibilities
>should also be examined. Too often, pre-treatment stability of the
>health outcome or functional measure is assumed rather than measured.
>The treatment should usually be one in which a short term effect is
>most plausible
>(as opposed to a subtle change in recovery curve), as changes in recovery
>curves are hard to detect unambiguously. The effects of other
>coincident events
>(sometimes called history effects) that might effect the outcome
>would need to be
>excluded: the best way to do this is to test whether the outcome
>increment or effect occurs reliably after the treatment is applied repeatedly
>to different individuals or groups.
>
>I learned of these designs studying Cook and Campbell (1979) and in
>econometric studies in graduate school, but much work has been done
>since then.
>
>Best regards,
>
>* Mark J.
>
>
>
>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
>
>>>> Rod Jackson <[log in to unmask]> 11/11/2005 8:51 PM >>>
>Dear Kukuh - you mention the GATE tool as a possible evaluation tool
>for case series. While the GATE intervention tool (downloadable from
>www.epiq.co.nz) is designed for appraising intervention studies that
>include both an exposure (i.e.intervention) and comparison group, you
>can think of a case series as an intervention study without an
>explicit comparison group. With this in mind the GATE tool or any
>other appraisal tool for intervention studies can be used to evaluate
>a case series.
>
>It is worth noting that if the occurrence of the outcome of interest
>is well known in people who don't receive the intervention described
>in the case series (i.e the equivalent of the comparison group in a
>standard controlled trial), then a case series can provide reasonable
>evidence of the effectiveness of an intervention. One of the most
>famous case series is the first group of patients (I think 5-10
>people with pneumonia) who received penicillin. Prior to penicillin,
>mortality was extremely high in patients with similar symptoms but it
>fell dramatically in those receiving penicillin - no RCT was required.
>
>regards Rod Jackson
>
>>Dear Anita,
>>
>>Just recently, I came across a document entitled: Grading the evidence:
>>case series scroing system. I believe this is part of the the Gate Tool.
>>In this particular,it was employed by the NZ Guidelines Group in
>>conducting systematic review on interventional pain management. In the
>>context of EBM, I think the list is reasonable. Here is the link:
>>http://www.acc.co.nz/wcm001/idcplg?IdcService=SS_GET_PAGE&nodeId=8012&ss
>>SourceNodeId=7975
>>I hope this helps.
>>Thank you.
>>
>>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]] On Behalf Of Anita von
>>Krogh
>>Sent: Friday, November 11, 2005 3:48 AM
>>To: [log in to unmask]
>>Subject: Checklists for case reports or case series?
>>
>>Dear list-members
>>
>>I work at the Norwegian Poisons Information Center where we respond to
>>telephone calls from the public and health personnel regarding
>>poisonings,
>>and I am a new member of this discussion list.
>>
>>We are presently revising the routines for quality grading of the
>>documentation on which we base our advice to the public and health
>>personnel. Our dilemma is that most of the available literature on
>>toxicology in human beings are case reports, summaries of case reports
>>or
>>case series. The checklists I have been able to locate don't cover these
>>
>>types of articles.
>>
>>We have attempted to make a checklist for case reports/case series, but
>>would like to hear if such a thing already exists. I wonder if any
>>member
>>of this list know if such a checklist exists, or of work to make one, or
>>
>>have opinions regarding it.
>>
>>I look forward to reading your response!
>>
>>Kind regards
>>Anita von Krogh
>>National Poisons Information Center
>>Directorate for Health and Social Affairs
>>Norway.
>
>
>--
>Rod Jackson
>Professor of Epidemiology
>Head of Section of Epidemiology and Biostatistics
>School of Population Health, Tamaki Campus
>Faculty of Medical & Health Sciences, University of Auckland
>100 Morrin Rd (cnr Merton & Morrin Roads), Glen Innes, Auckland
>Private Bag 92019
>Auckland, New Zealand
>
>Phone: +64 (0)9-3737599 ext 86343
>Fax: +64 (0)9-3737494
>e-mail: [log in to unmask]
>
>EPIQ website: http://www.epiq.co.nz
>
>email usually checked within 1 week of receipt
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