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Dear Editor, The trial has two arms: magsulf and placebo. In my opinion the
subjects should give informed consent and instead of blinding the
treatment, the subjects should be able to opt for which arm they would
like to participate. And lastly, instead of placebo some other treatment
like diazepam or phenytoin should have been given as denying treatment is
unethical. Moreover, the magsulf has severe side effects e.g. res...
Dear Editor, The trial has two arms: magsulf and placebo. In my opinion the
subjects should give informed consent and instead of blinding the
treatment, the subjects should be able to opt for which arm they would
like to participate. And lastly, instead of placebo some other treatment
like diazepam or phenytoin should have been given as denying treatment is
unethical. Moreover, the magsulf has severe side effects e.g. respiratory
rate goes down. Because of low therapeutic index, it has to be given
cautiously.
In this week's EBM, Bond and colleagues report a systematic review
entitled: 'Psychological consequences of false-positive screening
mammograms in the UK'.(1) Their two main outcomes are self-reported
questionnaires, and attendance at the next screening round.
Together with two colleagues, I conducted a systematic review in 2004
on the adequacy of measurement of short and long-term consequence...
In this week's EBM, Bond and colleagues report a systematic review
entitled: 'Psychological consequences of false-positive screening
mammograms in the UK'.(1) Their two main outcomes are self-reported
questionnaires, and attendance at the next screening round.
Together with two colleagues, I conducted a systematic review in 2004
on the adequacy of measurement of short and long-term consequences of
false-positive screening mammography.(2) We concluded that the generic
measures (GHQ, HADS and STAI) "should not be used to measure psychological
consequences of any kind of cancer screening" and that a condition-
specific measure (PCQ) was preferable.(2) We also concluded, "Given the
inadequacy of the measurement instruments used, any current conclusions
about the long-term consequences of false-positive results of screening
mammography must remain tentative."(2) Therefore, we conducted six focus
group interviews to test the content validity of the PCQ in a time frame
of 1-12 months after a false-positive screening mammography.3 Because we
had to make major changes to the PCQ, we developed a new questionnaire:
Consequences Of Screening in Breast Cancer (COS-BC).(3) We have validated
the COS-BC using the Rasch Item Response Theory model and found that the
measure is a reliable multi-dimensional instrument for short- and long-
term psychosocial consequences of false-positive screening
mammography.(4;5) Therefore, it is unfortunate that Bond and colleagues do
not discuss the inadequacy of the psychological measures included in their
systematic review, and that a valid and reliable self-reported outcome
measure with high content validity does exist. The inadequacy of the
generic measures included in Bond et al's review could also be a plausible
explanation as to why they found that: "Heterogeneity was such that meta-
analysis was not possible".
It is also difficult to understand why Bond and colleagues have
limited their review only to include trials conducted in the UK. Why
should we expect different psychological reactions to a false-positive
screening mammography in different countries? The COS-BC has been
translated, adapted, and tested for relevance in a Swedish context, and we
found essentially no differences in psychosocial consequences of false-
positive screening mammography in Denmark and Sweden.(6) Together with
other colleagues, I have conducted the same translation, adaptation, and
test of relevance of the COS-BC in Norway, the Netherlands, and Germany,
with the same result as in Sweden (these projects are in progress).
The second outcome of Bond and colleagues is attendance to the next
screening round after a false-positive mammography. In some countries,
researchers have found that these women have a higher attendance to the
next screening round than those with a normal screening result. In other
countries, researchers have found the opposite, or similar attendance
rates. In my qualitative single- and focus group-interviews, some women
said that they did not dare to go to next screening after all they had
experienced after a false-positive result.(4) Others said they did not
dare to stay away.(4) If the psychological impact of a false-positive
screening mammography can be ambivalent feelings about attendance to the
next screening round, re-attendance is a poor surrogate outcome for the
psychological impact of a false-positive screening mammography.
References
(1) Bond M, Pavey T, Welch K, et al.
Psychological consequences of false-positive screening mammograms in the
UK. Evid Based Med 2012.
(2) Brodersen J, Thorsen H, Cockburn J. The adequacy of measurement
of short and long-term consequences of false-positive screening
mammography. J Med Screen 2004;11(1):39-44.
(3) Brodersen J, Thorsen H. Consequences Of Screening in Breast
Cancer (COS-BC): development of a questionnaire. Scand J Prim Health Care
2008; 26(4):251-256.
(4) Brodersen J. Measuring psychosocial consequences of false-
positive screening results - breast cancer as an example. Department of
General Practice, Institute of Public Health, Faculty of Health Sciences,
University of Copenhagen: M?nedsskrift for Praktisk L?gegerning,
Copenhagen. ISBN: 87-88638-36-7; 2006.
(5) Brodersen J, Thorsen H, Kreiner S. Validation of a condition-
specific measure for women having an abnormal screening mammography. Value
in Health 2007;10(4):294-304.
(6) Bolejko A, Wann-Hansson C, Zackrisson S, et al.
Adaptation to Swedish and further development of the 'Consequences of
Screening - Breast Cancer' questionnaire: a multimethod study. Scand J
Caring Sci 2012.
One third of patients who undergo surgery will experience
postoperative nausea and vomiting (PONV) which can be very distressing
(wound dehiscences and pulmonary complications)[1].
Rawlinson and colleagues [2] have made an excellent systematic review of
randomised controlled trials, whose conclusions included the confirmation
of intravenous dexamethasone and ondansetron (5-HT3 antagonist) as
effective...
One third of patients who undergo surgery will experience
postoperative nausea and vomiting (PONV) which can be very distressing
(wound dehiscences and pulmonary complications)[1].
Rawlinson and colleagues [2] have made an excellent systematic review of
randomised controlled trials, whose conclusions included the confirmation
of intravenous dexamethasone and ondansetron (5-HT3 antagonist) as
effective drugs for prophylaxis of PONV when compared to controls.
However, a recent FDA safety alert [3]refers that a single 32 mg
intravenous dose of ondansetron may affect the electrical activity of the
heart (QT interval prolongation), which could predispose patients to
develop an abnormal and potentially fatal heart rhythm known as "torsades
de pointes". Additionally, ondansetron is a very expensive drug, which in
the present financial crisis is very relevant.
So, it may be useful to remember the old and low-priced antiemetic
metoclopramide as a cheaper and safer alternative to ondansetron.
Metoclopramide has not yet been associated with "torsades de pointes". As
it blocks dopaminergic (D2) receptors, it is contraindicated in
Parkinson's disease, and with chronic use may induce extrapyramidal
reactions. But, for a single or short therapeutic course this problem
seems not frightening, and furthermore, it has the advantage to increase
GI motility, which may be useful to reduce the opioid gastric side
effects, and if used before anaesthesia induction, it may also mitigate
the danger of gastric content aspiration.
Reference
1- Apfel CC, Korttila K, Abdalla M, et al. A factorial trial of six
interventions for the prevention of postoperative nausea and vomiting. N
Engl J Med 2004;350:2441-51.
2- Evid Based Med. 2012;17(3):75-80.
3- FDA at:
http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm272041.htm
Disclosure of conflicts of interest in Japanese randomized controlled
trials
Dear Editor,
Disclosure of potential conflicts of interest (COI) is essential in
interpreting randomized controlled trials with less risk of bias. In
2008, the Japanese Ministry of Health, Labour and Welfare issued an
ethical guideline for clinical research that endorsed disclosure of
potential COI 1. To assess impact of the gu...
Disclosure of conflicts of interest in Japanese randomized controlled
trials
Dear Editor,
Disclosure of potential conflicts of interest (COI) is essential in
interpreting randomized controlled trials with less risk of bias. In
2008, the Japanese Ministry of Health, Labour and Welfare issued an
ethical guideline for clinical research that endorsed disclosure of
potential COI 1. To assess impact of the guideline, we investigated the
proportion of Japanese randomized controlled trial articles which
disclosed COI published during 2009-2010.
We used ICHUSHI Web 2, the largest database of medical literature in
Japan run by the Japan Medical Abstracts Society, to identify articles
with the following characteristics; post-marketing, double-blind,
randomized controlled trial of prescription drugs; published by official
journals of medical associations belonging to the Japanese Association of
Medical Science; conducted in Japan and by public research institute
(i.e., not by pharmaceutical company).
We identified 18 articles which met the above criteria. Funding
source(s) was disclosed in 56% (10/18). Pre-registration was indicated in
17% (3/18). Study endpoint was clearly specified in 50%. Most trials
(88%) reported results favoring trial drugs over comparator drugs or
placebo.
The 18 articles were published in 14 journals. In submission
requirements of these journals during 6-12 months prior to the
publication, disclosure of potential COI was requested in 43% (6/14). It
was requested in 55% (6/11) of journals written in English and 0% (0/3) in
Japanese.
These findings suggest that Health Ministry's guideline has not taken
full effects, and that caution should be practiced in interpreting
Japanese randomized controlled trials for their financial and scientific
integrity.
References
1. Ministry of Health, Labour and Welfare. ethical guideline for clinical
research,2008(http://www.mhlw.go.jp/general/seido/kousei/i-kenkyu/#4)
2. Japan Medical Abstracts SocietyVer.4(http://www.jamas.or.jp/)
As a practicing clinician, who reads Evidence Based Medicine to keep
up to date with significant progress in medicine, I cannot help feeling
perplexed about the review of Ambrosy and Gheorghiade on the article by
Zannad et al (Eplerenone in patients withsystolic heart failure and mild
symptoms, NEJM 2011; 364 : 11-21). Throughout their commentary, the
reviewers fail to mention that the main conclusion...
As a practicing clinician, who reads Evidence Based Medicine to keep
up to date with significant progress in medicine, I cannot help feeling
perplexed about the review of Ambrosy and Gheorghiade on the article by
Zannad et al (Eplerenone in patients withsystolic heart failure and mild
symptoms, NEJM 2011; 364 : 11-21). Throughout their commentary, the
reviewers fail to mention that the main conclusion of the study,namely
that a potassium sparing diuretic is beneficial in systolic heart failure
while increasing the risk of hyperkalaemia, is hardly innovative, since
aldosterone-receptor blockade has been part of recommended therapy for a
number of years (1,2). This being the case, it is also perplexing why
Ambrosy and Gheorghiade fail to mention that the choice of a placebo in
the control group, and the excess mortality hence recorded,is particularly
difficult to justify under the Helsinki Declaration of Human Rights,
according to which a new method should be tested against the best
available alternative. Ethical considerations aside, such an unbalanced
comparison artificially expands any measure of relative risk reduction in
mortality achieved by Eplerenone. It also deprives the prescriber,
perphaps not unintentionally in an industry-funded trial, of an answer to
the question of whether the significant extra cost of this drug buys any
substantial benefit over that achieved by Spironolactone. If the journal
really prides itself in providing a fair and comprehensive review of
recent medical developments, these omissions should be urgently rectified.
References
1) Hunt SA, Abraham WT, Chin MH et al. 2009 focused update incorporated
into the ACC/AHA 2005 Guidelines for the diagnosis and management of heart
failure in adults : A report from the American College of cardiology
Foundation/American Heart Association Task Force on Practice Guidelines;
developed in collaboration with the International Sociaty for Heart and
Lung Transplantation. Circulation 2010;121 (12):e258.
2) Dickstein K, Cohen-Solal A, Filippatos G et al. ESC Guidelines for the
diagnosis and treatment of acute and chronic heart failure 2008 - The Task
Force for the diagnosis and treatment of acute and chronic heart failure
2008 of teh European Society of Cardiology; developed in collaboration
with the Heart Failure Association ot the ESC (HFA) and endorsed by the
European Society of Intensive Care Medicine (ESICM). Eur J Heart Failure 2008;10:933-989.
We welcome the publication of Medow and Lucey in the December issue, describing a qualitative approach to Bayes' theorem [1]. Especially because the authors provide a new impulse to the development of clinician-friendly strategies for teaching clinical decision making skills.
However, the approach proposed by the authors is not new. We reported a didactic model based on a visual representation of B...
We welcome the publication of Medow and Lucey in the December issue, describing a qualitative approach to Bayes' theorem [1]. Especially because the authors provide a new impulse to the development of clinician-friendly strategies for teaching clinical decision making skills.
However, the approach proposed by the authors is not new. We reported a didactic model based on a visual representation of Bayesian logic on a logarithmic scale eight years ago in peer-reviewed journals [ 2-4]. Our logical frame is also categorical and similar to the one proposed here, but it is more elaborate: it allows for the extremes of the probability scale, it provides more test power categories, and it covers asymmetry of test results.
The authors report a major limitation of their model: it applies to the intermediate range of probabilities (10-90), leaving the very high post test probabilities often at stake in specialist care and the very low concerned in general practice to the discretion of the clinician. In our model, using a log odds scale, findings with a "weak" power allow to advance or regress half step towards or away from diagnosis, "good" arguments one step, "strong" arguments one and a half and "very strong" two steps. In the author's model only two categories of test values are considered, good and very good. In case of weaker tests, the authors propose to change the probability category scale. Our model offers four categories of power of tests, reportedly also used by Alan Turing 50 years ago, corresponding to the log10 of the likelihood ratio rounded to half the unit [5].
Finally, their model somehow suggests symmetry of test results, a major misconception of junior clinicians. This symmetry applies to their example of a nuclear stress test, but not e.g., to D-dimers which are useful to exclude a pulmonary embolism, but add almost nothing for confirmation of the diagnosis.
We apply this approach for more than a decade in under and post graduate teaching and in clinical decision making workshops in different countries of Europe, Asia, Africa and South America with enthusiastic acceptance by trainees, but the effect of training with this approach still needs thorough assessment [6].
References
[1] Medow MA, Lucey CR. A qualitative approach to Bayes' theorem. Evid Based Med 2011;16(6):163-167.
[2] Van Puymbroeck H, Remmen R, Denekens J, et al. Teaching problem solving and decision making in undergraduate medical education: an instructional strategy. Med Teach 2003;25(5):547-550.
[3] Van Den Ende J, Bisoffi Z, Van Puymbroek H, et al. Bridging the gap between clinical practice and diagnostic clinical epidemiology: pilot experiences with a didactic model based on a logarithmic scale. J Eval Clin Pract 2007;13(3):374-380.
[4] Van Den Ende J, Moreira J, Basinga P, et al. The trouble with likelihood ratios. Lancet 2005;366(9485):548.
[5] Good I. AM Turing's statistical work in world war II. (Studies in the history of probability and statistics XXXVII). Biometrika 1979;66(2):393-396.
[6] Moreira J, Bisoffi Z, Narvaez A, et al. Bayesian clinical reasoning: does intuitive estimation of likelihood ratios on an ordinal scale outperform estimation of sensitivities and specificities? J Eval Clin Pract 2008;14(5):934-940.
The dorsal horns are not merely passive transmission stations but
sites at which dynamic activities (inhibition, excitation and modulation)
occur. [18]
Via a series of filters and amplifiers, the nociceptive message is
integrated and analysed in the cerebral cortex, with interconnections with
various areas. [1]
The processing of pain takes place in an integrated matrix throughout...
The dorsal horns are not merely passive transmission stations but
sites at which dynamic activities (inhibition, excitation and modulation)
occur. [18]
Via a series of filters and amplifiers, the nociceptive message is
integrated and analysed in the cerebral cortex, with interconnections with
various areas. [1]
The processing of pain takes place in an integrated matrix throughout
the neuroaxis and occurs on at least three levels, at peripheral, spinal,
and supraspinal sites. [9]
Knowledge of the modalities of pain control is essential to correctly
adapt treatment strategies (drugs, neurostimulation, psycho-behavioural
therapy, etc.).
Dysfunction of pain control systems causes neuropathic pain. [1]
Spinal Cord Stimulation modalities evolved from the gate-control
theory postulating a spinal modulation of noxious inflow. [16] [2] [7]
[11] [12] [15] [17] [20] [22] [23] [24] [25] [26]
It has been demonstrated in multiple studies that dorsal horn
neuronal activity caused by peripheral noxious stimuli could be inhibited
by concomitant stimulation of the dorsal columns. [8]
Pain relief was more prominent at pain ascending through C fibers
than pain ascending through Adelta fibers [21]
Many theories on the mechanism of action of Spinal Cord Stimulation
have been suggested, including activation of gate control mechanisms,
conductance blockade of the spinothalamic tracts, activation of
supraspinal mechanisms, blockade of supraspinal sympathetic mechanisms,
and activation or release of putative neuromodulators. [14]
At present, Spinal Cord Stimulation is a well established form of
treatment for failed back surgery syndrome, complex regional pain
syndromes (CRPS), low back pain with radiculopathy and refractory pain due
to ischemia. [4] [3] [8] [13]
Stimulation produced analgesia can provide a level of analgesia and
efficacy that is unattainable by other treatment modalities. [19]
Spinal Cord Stimulation for the treatment of chronic pain is cost-
effective when used in the context of a pain treatment continuum. [14]
Precise subcutaneous field stimulation is targeted to specific areas
of neuropathic pain. [6]
We aim at attenuation or blockade of pain through intervention at the
periphery, by activation of inhibitory processes that gate pain at the
spinal cord and brain. [9]
Segmental noxious stimulation produces a stronger analgesic effect
than segmental innocuous stimulation. [10]
That is exactly what intradermal sterile water or subcutaneous saline
injections do!
Chloride, used in subcutaneous "sham" injections, independently
regulates the pain pathway. [5]
In these studies there was no valid control group receiving sham
injections.
In the past, other researchers, in similar studies, have also had
difficulties in blinding and comparing with control groups. [4]
These RCTs simply compared an established therapeutic intervention to
another established therapeutic intervention.
References
[1] Labat JJ, Robert R, Delavierre D, et al. Anatomy and physiology of chronic pelvic and perineal pain. Prog Urol 2010;20(12):843-52. Epub 2010 Oct 20.
[2] Moharic M, Burger H. Effect of transcutaneous electrical nerve stimulation on sensation
thresholds in patients with painful diabetic neuropathy: an observational
study. Int J Rehabil Res 2010;33(3):211-7.
[3] Shrivastav M, Musley S. Spinal cord stimulation for complex regional pain syndrome.
Conf Proc IEEE Eng Med Biol Soc 2009;2009:2033-6.
[4] Kunnumpurath S, Srinivasagopalan R, Vadivelu N. Spinal cord stimulation: principles of past, present and future practice:
a review. J Clin Monit Comput 2009;23(5):333-9.
[5] Price TJ, Cervero F, Gold MS, et al. Chloride regulation in the pain pathway. Brain Res Rev 2009;60(1):149-70. Epub 2008 Dec 31.
[6] Henderson JM. Peripheral nerve stimulation for chronic pain. Curr Pain Headache Rep 2008;12(1):28-31.
[7] Handwerker HO. From Descartes to fMRI. Pain theories and pain concepts. Schmerz 2007;21(4):307-10, 312-7.
[9] DeLeo JA. Basic science of pain. J Bone Joint Surg Am 2006;88 Suppl 2:58-62.
[10] Defrin R, Ariel E, Peretz C. Segmental noxious versus innocuous electrical stimulation for chronic pain
relief and the effect of fading sensation during treatment. Pain 2005;115(1-2):152-60.
[11] Craig AD. Pain mechanisms: labeled lines versus convergence in central processing. Annu Rev Neurosci 2003;26:1-30. Epub 2003 Mar 6.
[12] Staal JB, Hlobil H, van Tulder MW, et al. Return-to-work interventions for low back pain: a descriptive review of
contents and concepts of working mechanisms. Sports Med 2002;32(4):251-67.
[14] Krames E. Spinal Cord Stimulation: Indications, Mechanism of Action, and Efficacy. Curr Rev Pain 1999;3(6):419-426.
[15] Costentin J. Pain and its main transmitters. Ann Pharm Fr 2000;58(2):77-83.
[16] Meyerson BA, Linderoth B. Mechanisms of spinal cord stimulation in neuropathic pain. Neurol Res 2000;22(3):285-92.
[17] Yaksh TL. Regulation of spinal nociceptive processing: where we went when we
wandered onto the path marked by the gate. Pain 1999;Suppl 6:S149-52.
[18] Melzack R. From the gate to the neuromatrix. Pain 1999;Suppl 6:S121-6.
[19] Stanton-Hicks M, Salamon J. Stimulation of the central and peripheral nervous system for the control
of pain. J Clin Neurophysiol. 1997;14(1):46-62.
[20] Humphries SA, Johnson MH, Long NR. An investigation of the gate control theory of pain using the experimental
pain stimulus of potassium iontophoresis. Percept Psychophys 1996 ;58(5):693-703.
[21] Kakigi R, Watanabe S. Pain relief by various kinds of interference stimulation applied to the
peripheral skin in humans: pain-related brain potentials following CO2
laser stimulation. J Peripher Nerv Syst. 1996;1(3):189-98.
[22] Davis P. Pain: opening up the gate control theory. Nurs Stand. 1993;7(45):25-7.
[23] Cambier J. Gate control of the nociceptive message: applications to the treatment of pain. Bull Acad Natl Med 1989;173(7):855-60; discussion 860-1.
[24] Benabid AL, Henriksen SJ, McGinty JF, et al. Thalamic nucleus ventro-postero-lateralis inhibits nucleus
parafascicularis response to noxious stimuli through a non-opioid pathway. Brain Res 1983;280(2):217-31.
[25] Malow RM, Dougher MJ. A signal detection analysis of the effects of transcutaneous stimulation
on pain. Psychosom Med. 1979 Mar;41(2):101-8.
[26] Goldman DE. Gate control of ion flux in axons. J Gen Physiol 1965;48:SUPPL:75-7.
Although the accuracy of a mercury sphygmomanometer can be debated,
automatic and semi-automatic devices which inflate the cuff often do so to
well above the systolic pressure and can cause patients considerable
discomfort even when an appropriate cuff size has been used. These devices
frequently re-inflate for a variety of reasons, but out of control of the
operator who is waiting for a reading.
Although the accuracy of a mercury sphygmomanometer can be debated,
automatic and semi-automatic devices which inflate the cuff often do so to
well above the systolic pressure and can cause patients considerable
discomfort even when an appropriate cuff size has been used. These devices
frequently re-inflate for a variety of reasons, but out of control of the
operator who is waiting for a reading.
Anecdotally, I have had several patients request I use what they call
the "old fashioned" mercury sphygmomanometer at future consultations.
It would not be surprising to find that the "error" rate in blood
pressure determinations with the "old fashioned" sphygmomanometer was due,
in part, to a faulty technique by the individuals taking the blood
pressures. Remarkably, little or no time is spent in teaching medical
students the proper technique for blood pressure determination including
the appropriate cuff size to use, the various audible phases, etc. One
ca...
It would not be surprising to find that the "error" rate in blood
pressure determinations with the "old fashioned" sphygmomanometer was due,
in part, to a faulty technique by the individuals taking the blood
pressures. Remarkably, little or no time is spent in teaching medical
students the proper technique for blood pressure determination including
the appropriate cuff size to use, the various audible phases, etc. One
cannot determine if there is an exaggerated second phase of Karotkoff
sounds, which is an indicator of the presence of atherosclerotic disease,
with an electronic blood pressure apparatus. Neither can one determine the
presence of a pulsus paradoxicus with an electronic device. The relegation
of the stethoscope to the rubbish bin or museum was predicted decades ago
and has not yet taken place. I, for one, will continue to use my
stethoscope and take my patients' blood pressures with a manual
sphygmomanometer, thank you.
Bayes theorem can only be applied properly when considering a single
diagnosis or its absence e.g. the presence or absence of asymptomatic
diabetes mellitus, hypothyroidism, hyperlipidaemia, cervical cancer,
breast cancer, etc. These asymptomatic situations are very important in
the clinical setting and also in the community. It is in these situations
that the reasoning described in this paper can be...
Bayes theorem can only be applied properly when considering a single
diagnosis or its absence e.g. the presence or absence of asymptomatic
diabetes mellitus, hypothyroidism, hyperlipidaemia, cervical cancer,
breast cancer, etc. These asymptomatic situations are very important in
the clinical setting and also in the community. It is in these situations
that the reasoning described in this paper can be used. However, much of
our time is taken up with differential diagnosis, which cannot be modeled
by Bayes theorem (which explains why it is not often used as pointed out
by the authors).
When dealing with differential diagnoses, we must first choose a good
diagnostic lead [1, 2, 3] (or pivot [4]) e.g. acute abdominal pain, which
has a limited differential diagnosis. Tim de Dombal and his colleagues
did something similar [5]. We then choose a diagnosis from the list (e.g.
appendicitis) and look for findings (e.g. guarding) that occur commonly in
that chosen diagnosis and rarely (or never) in at least one other
diagnosis in the list (e.g. non-specific abdominal pain). This 'other'
diagnosis thus becomes less probable (or is ruled out if the finding
cannot by definition occur in people with that diagnosis). The chosen
diagnosis (e.g. appendicitis) correspondingly becomes more probable. A
'definitive' or 'sufficient' criterion (e.g. a red swollen appendix at
surgery would confirm a diagnosis.
A different 'reasoning by elimination theorem' is thus required to
model this reasoning process, which uses Bayes theorem as the starting
point of its proof [1, 2]. The author's qualitative approach in this
paper could also be applied to this 'reasoning by elimination theorem'
that models differential diagnostic reasoning.
References
1. Llewelyn DEH. Mathematical analysis of the diagnostic relevance of
clinical findings. Clin Sci 1979;57(5):477-479.
2. Llewelyn H, Ang HA, Lewis K, et al. The Oxford Handbook of
Clinical Diagnosis, 2nd ed. Oxford University Press, Oxford 2009;754-
772.
3. Lipschick GY, Von Feldt JM, Frame L, et al. The Oxford American Handbook of Clinical Diagnosis. Oxford University
Press, New York 2009;18-27.
4. Eddy DM, Clanton CH. The art of diagnosis: solving the clinico-
pathological conference. N Eng J Med. 1982;306:1263-1268.
5. Horrocks JC, de Dombal T. Computer-aided diagnosis:
description of an adaptable system, and operational experience with 2,034
cases. Br Med J 1972; 2: 5-9.
Dear Editor, The trial has two arms: magsulf and placebo. In my opinion the subjects should give informed consent and instead of blinding the treatment, the subjects should be able to opt for which arm they would like to participate. And lastly, instead of placebo some other treatment like diazepam or phenytoin should have been given as denying treatment is unethical. Moreover, the magsulf has severe side effects e.g. res...
Dear Editor,
In this week's EBM, Bond and colleagues report a systematic review entitled: 'Psychological consequences of false-positive screening mammograms in the UK'.(1) Their two main outcomes are self-reported questionnaires, and attendance at the next screening round.
Together with two colleagues, I conducted a systematic review in 2004 on the adequacy of measurement of short and long-term consequence...
Dear Editor,
One third of patients who undergo surgery will experience postoperative nausea and vomiting (PONV) which can be very distressing (wound dehiscences and pulmonary complications)[1]. Rawlinson and colleagues [2] have made an excellent systematic review of randomised controlled trials, whose conclusions included the confirmation of intravenous dexamethasone and ondansetron (5-HT3 antagonist) as effective...
Disclosure of conflicts of interest in Japanese randomized controlled trials
Dear Editor,
Disclosure of potential conflicts of interest (COI) is essential in interpreting randomized controlled trials with less risk of bias. In 2008, the Japanese Ministry of Health, Labour and Welfare issued an ethical guideline for clinical research that endorsed disclosure of potential COI 1. To assess impact of the gu...
Dear Editor,
As a practicing clinician, who reads Evidence Based Medicine to keep up to date with significant progress in medicine, I cannot help feeling perplexed about the review of Ambrosy and Gheorghiade on the article by Zannad et al (Eplerenone in patients withsystolic heart failure and mild symptoms, NEJM 2011; 364 : 11-21). Throughout their commentary, the reviewers fail to mention that the main conclusion...
Dear editor,
We welcome the publication of Medow and Lucey in the December issue, describing a qualitative approach to Bayes' theorem [1]. Especially because the authors provide a new impulse to the development of clinician-friendly strategies for teaching clinical decision making skills.
However, the approach proposed by the authors is not new. We reported a didactic model based on a visual representation of B...
Dear Editors,
The dorsal horns are not merely passive transmission stations but sites at which dynamic activities (inhibition, excitation and modulation) occur. [18]
Via a series of filters and amplifiers, the nociceptive message is integrated and analysed in the cerebral cortex, with interconnections with various areas. [1]
The processing of pain takes place in an integrated matrix throughout...
Although the accuracy of a mercury sphygmomanometer can be debated, automatic and semi-automatic devices which inflate the cuff often do so to well above the systolic pressure and can cause patients considerable discomfort even when an appropriate cuff size has been used. These devices frequently re-inflate for a variety of reasons, but out of control of the operator who is waiting for a reading.
Anecdotally, I...
It would not be surprising to find that the "error" rate in blood pressure determinations with the "old fashioned" sphygmomanometer was due, in part, to a faulty technique by the individuals taking the blood pressures. Remarkably, little or no time is spent in teaching medical students the proper technique for blood pressure determination including the appropriate cuff size to use, the various audible phases, etc. One ca...
Dear Editor,
Bayes theorem can only be applied properly when considering a single diagnosis or its absence e.g. the presence or absence of asymptomatic diabetes mellitus, hypothyroidism, hyperlipidaemia, cervical cancer, breast cancer, etc. These asymptomatic situations are very important in the clinical setting and also in the community. It is in these situations that the reasoning described in this paper can be...
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