Re a) & c) - Not necessarily !
- just on the basis of your message:
1. If overdiagnosis is less than about 50%, then at least one 'true diagnosis' (presumably patients where treatment could be beneficial, albeit doubtless some downsides as well) is made for every misdiagnosis. If eg screening-enabled earlier treatment of 2 'true' cases avoids 1 death (seems unlikely to me, but without knowing much about the efficacy of treatment, and anyway 'avoiding a death' is a bit vague ...) then the conclusion that "for every two overdiagnosed cases there is at least one death avoided" would be true. etc.
'for every one or two' could in any case be considered a (large) uncertainty range.
2. not clear from your extract whether it is the authors of the recent reviews, or of the WHO paper, who consider the balance of benefit / harm appropriate ?
3. By doing some sensitivity analyses with a range of patient values, as well as range of the relevant probabilities, it might be possible to conclude that almost all patients would think screening beneficial, even given the uncertainties. I have no idea whether this has, in fact, been done.
4. Even if screening is very beneficial for almost all patients, that is not an excuse for not informing patients and allowing / helping them to make the right decision for themselves - where they want to (some will doubtless want to simply delegate the decision to the health professional). I suppose insurance companies might, in places where healthcare is paid for by insurance, query paying for treatment which could have been avoided via screening which was refused (if such treatment ever arises) ?
David
----- Original Message -----
From: "OWEN DEMPSEY" <[log in to unmask]>
To: [log in to unmask]
Sent: Saturday, 13 December, 2014 7:16:59 AM
Subject: Re: WHO position paper mammography screening
Just to ask again, do other people see a very profound internal contradiction within this WHO position statement, a logical numerical contradiction:
The WHO paper again:
On overdiagnosis, (where if not a 'false positive', then we need a new word for the diagnosis, this might be 'faux-real-cancer' where the diagnosis and the word 'cancer' itself on its own is inadequate, it has a residue of non-meaning.)
The WHO document states, on 'overdiagnosis':
"The estimates vary greatly(from 0% to 54%) according to the method used, the source of the data and the definition of overdiagnosis. Thus, the evidence based on the current available data is low. Two recent reviews estimated that for every one or two overdiagnosed cases, at least one death due to breast cancer was avoided, a balance between benefit and harm considered to be appropriate."
My questions:
a) Is it true to say: if over diagnosis (O/D) is between 0 and 54%, AND 2 x O/D = 1 life saved; then the numbers of lives saved will also have a range of uncertainty similar to 0-54%?
b) If this is true shouldn't the position statement be challenged?
c) Does the word 'appropriate' here, have the rhetorical power to prejudge the decision that women 'should' make about being screened (making talk of shared decision making at best meaningless and at worst exploitative)
d) Why are the estimates of the Norwegian Cochrane review (that prompted the Marmot review in the UK) not included in this benefit-harm estimation?
Owen
On 12 December 2014 at 17:33, write words < [log in to unmask] > wrote:
Yes , which is why recommendations have been changed to increase the intervals between screenings. This reduces harms without losing much benefit. (and the benefits are clearer with this screening.)
Russell Harris at UNC has done a lot of work on this.
http://uncnewsarchive.unc.edu/2013/07/09/outdated-practice-of-annual-cervical-cancer-screenings-may-cause-more-harm-than-good-2/
-Christie
On Dec 12, 2014, at 2:22 AM, Tess Harris < [log in to unmask] > wrote:
Are there similar concerns about cervical cancer screening?
Is there evidence of overdiagnosis, unnecessary biopsies etc?
Tess
On 12 Dec 2014, at 07:04, write words < [log in to unmask] > wrote:
Yes, in my experience interviewing physicians, many, if not most, do not understand point 1.
-Christie
On Dec 11, 2014, at 2:15 PM, Juan Gérvas < [log in to unmask] > wrote:
-excellent paper, Christie
-i have distributed it in the Net
-just to mention
1/ that most females (and many physicians) think that "overdiagnosis" is an error of diagnosis (a false positive) not an error of prognosis (it is a true positive, but of a non-invasive cancer)
http://equipocesca.org/en/english-overdiagnosis-as-an-extreme-form-of-length-time-bias-breast-cancer-screening-as-an-example/
2/ that most females (and many physicians) do not know that mammography produces cancer (90 radiation-related cancer per 100.000)
http://onlinelibrary.wiley.com/doi/10.3322/caac.21132/full
3/ that in dense breast supplemental ultrasonography, 1000 females, averted 0.36 a breast cancer deaths, 354 unnecesary biopsies
http:// annals.org/article.aspx?a rticleid=2020458 …
-this, and more, is under the logo " Not without shared decision-making ".
http://apps.who.int/iris/bitstream/10665/137339/1/9789241507936_eng.pdf?ua=1&ua=1
-un saludo
-juan gérvas
El 11/12/2014 21:43, Philipp Dahm escribió:
Nice essay, Christie! I wonder how you’d feel about prostate cancer screening….
Greetings
Ph*
Philipp Dahm, MD, MHSc, FACS
Professor of Urology and Vice Chair of Veterans Affairs, University of Minnesota
Director for Surgery/Specialty Care Service Line Research Activities
Coordinating Editor, Cochrane Prostatic Diseases & Urological Cancers (PDUC) Group
Minneapolis VA Health Care System, Urology Section 112D
One Veterans Drive
Minneapolis, MN 55417
Phone: 612 467 3532
Fax: 612 467 2232
Email: [log in to unmask]
On Dec 11, 2014, at 12:02 PM, write words < [log in to unmask] > wrote:
Owen,
I’m a journalist, not a physician, but I outlined the information that I believe women need to know to make an informed decision on mammography in this recent JAMA Internal Medicine essay. You can access the full text using this link .
And here’s another recent piece that touches on some of these issues, The case against early cancer detection .
Best,
Christie
Christie Aschwanden
Email: [log in to unmask]
Website: www.christieaschwanden.com
Blog: www.lastwordonnothing.com/category/christie/
Twitter: @cragcrest
On Dec 11, 2014, at 10:18 AM, OWEN DEMPSEY < [log in to unmask] > wrote:
page 21 of WHO position paper on mammography states:
"The association between mammography screening and overdiagnosis
has been demonstrated consistently across studies and is likely to be
supported by high-quality evidence. However, there is significant uncertainty
about the magnitude of overdiagnosis in the different age groups,
particularly in younger and older women. The estimates vary greatly
(from 0% to 54%) according to the method used, the source of the data and
the definition of overdiagnosis. Thus, the evidence based on the current
available data is low. Two recent reviews estimated that for every one
or two overdiagnosed cases, at least one death due to breast cancer was
avoided, a balance between benefit and harm considered to be appropriate."
This seems like an unhelpful conflation of issues. How can so much uncertainty about the rate of diagnosis tranlsate into so much certainty?
What is a womans chances of being overdiagnosed on a first screening between 40 and 49 say? And what are her chances of havng her life saved by this screening episode?
Owen
On 11 December 2014 at 08:34, Juan Gérvas < [log in to unmask] > wrote:
OMS: valoración del cribado de mamografía. No sin el consentimiento informado. Sólo con pruebas de calidad moderada.
WHO position paper on mammography screening. Not without shared decision-making. O nly with moderate quality evidence.
http://apps.who.int/iris/bitstream/10665/137339/1/9789241507936_eng.pdf?ua=1&ua=1
-un saludo
-juan gérvas
--
Owen Dempsey
07760 164420
GP Substance Misuse Locala and Kirklees Lifeline
PhD student University of Manchester, Dept of Education
Este mensaje no contiene virus ni malware porque la protección de avast! Antivirus está activa.
--
Owen Dempsey
07760 164420
GP Substance Misuse Locala and Kirklees Lifeline
PhD student University of Manchester, Dept of Education
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