Shouldn't the RCT be done in such a way that the placebo also has
Camphor and peppermint oil in identical concentration to the actual cream?[1] It is already known that the latter two can have a good effect on osteoarthritis, especially in the elderly.
Reference
1. Reginster J-Y. A topical cream containing glucosamine and chondroitin sulphate reduced joint pain in osteoarthritis of...
Shouldn't the RCT be done in such a way that the placebo also has
Camphor and peppermint oil in identical concentration to the actual cream?[1] It is already known that the latter two can have a good effect on osteoarthritis, especially in the elderly.
Reference
1. Reginster J-Y. A topical cream containing glucosamine and chondroitin sulphate reduced joint pain in osteoarthritis of the knee. Evid Based Med 2003; 8: 154.
I see many results in which potassium falls (a little) above the normal range.[1] I was wondering at what level I should be concerned about sudden death being the presenting symptom.
I reflected that the context in which the result was found affects my decision making.
A routine test which identifies a raised value, is less alarming than a test which is done for a reason, such as the presence of s...
I see many results in which potassium falls (a little) above the normal range.[1] I was wondering at what level I should be concerned about sudden death being the presenting symptom.
I reflected that the context in which the result was found affects my decision making.
A routine test which identifies a raised value, is less alarming than a test which is done for a reason, such as the presence of symptoms or perhaps because of a medication change.
This is analagous to the significance of a symptom or sign in the context of a focussed query versus routine enquiry (or screening).
One way of looking at it is in terms of the test characteristics of a diagnostic test versus a screening test. A screening test may have a higher cut point to increase specificity and reduce false positives. A diagnostic test may have a lower cut point to increase sensitivity and reduce false negatives.
Alternatively, looking at it as a Bayesian probability calculation, when doing the test for a reason (eliciting a symptom or sign for a reason) the prior probability (of a problem) is greater and hence one is influenced more even if the test (or symptom/sign) has a relatively small positive LR.
This is a very roundabout way of saying that if in doing routine annual bloods on a patient with hypertension treated with an ACE, I discovered a K of 6 say, I would perhaps feel this was not a cause for urgency. Conversely if someone presented with weakness and palpitations having recently commenced an ACE for diabetic nephropathy I might judge the same value of K to be more serious.
On the basis of this I would be interested to know what type of patients were included in the prognostic studies identified. Were they a broad selection of the population, such as seen in primary care, or were they perhaps patients more at risk of hyperkalemia, and its consequences, such as patients with diabetic nephropathy? Similarly, what was the context in which ECGs were related to potassium levels?
Reference
1. de Palma J R, Glasziou P. The first symptom of hyperkalaemia is death. Evid Based Med 2004; 9: 134-135
I read with optimism the note from Dr. Glasziou. It is encouraging to
know that systematic reviews on diagnostic tests are being considered as
part of national Cochrane movements. We badly need them. We have been
involved in this task ever since 1995 and published two systematic reviews
[1,2]. Quality of primary studies and methodological problems need to be
studied and new tools need to be developed....
I read with optimism the note from Dr. Glasziou. It is encouraging to
know that systematic reviews on diagnostic tests are being considered as
part of national Cochrane movements. We badly need them. We have been
involved in this task ever since 1995 and published two systematic reviews
[1,2]. Quality of primary studies and methodological problems need to be
studied and new tools need to be developed. Summary receiver operating
characteristics curve (sROC curve) is one method for pooling results of
primary studies. However, there are still many drawbacks that pooled sROC
curves can not tackle to date. The clinician needs to know the best
diagnostic test or clinical feature at different thresholds and in
different clinical scenarios. And sROC curves are not able to show them.
Pooled likelihood ratios (LRs) and diagnostic odds ratios (DORs) have been
proposed recently and seem attractive and quite easy to interpret for busy
practitioners [3]. Hopefully there will be an increasing number of
clinicians interested in translating the daily clinical problems into
answerable questions and trying the next brave step of trying to get their
own answers through the conduction of systematic reviews.
Evidence-based medicine has definitely influenced the practice of
medicine all over the world. Those of us teaching and practicing in
developing countries face several difficulties for testing whether EBM
works or not in our particular settings. Our patients are often poor and
have widely differing cultural backgrounds. We must adapt our discourse to
those characteristics. And this is a very difficult task to fulfill. But
our daily experience -pending to be systematically reported- strongly
suggests that it is not an impossible task.
Access to the medical literature used to be a nightmare for us.
Fortunately, we have now a substantial amount of full literature freely
available. Hinari must be commended for the reduction of this knowledge
gap between rich and poor nations. However, training in searching,
retrieving and most of all, critically appraising of the literature is
still in its infancy. We risk to be asphyxiated by all the published
studies if we do not develop systematic ways of recognizing the bad
literature from the good and relevant one. I wonder how far this pathway
has progressed in the way of a strong network involving clinicians and
researchers from developed and developing countries alike. Access to
Internet is still a pending problem. Free access to the medical literature
will be useless if medical students and physicians are charged with
expensive fees imposed by private companies that control access to
Internet, often in a monopoly way, like in Peru.
Finally, I was looking for some thoughts on the evidence base for
public health and health policy issues in Dr. Glaszious’s note, but found
nothing. Let’s hope that more systematic reviews on public health
interventions will become available. They are too scarce now. And this
evidence-based policy making will very likely need the discussion and
development of new standards in addition to systematic reviews of
randomized controlled trials [4]. Too many children are dying, almost all
in poor countries [5]. We have effective interventions for avoiding most
of these deaths [6] and it is immoral that they are not reaching those
that need them most. But in addition we need to study the effectiveness of
different delivery mechanisms of single effective interventions and on how
to strengthen health systems in the developing world [7]. Randomized
controlled trials are often not feasible or are unethical when we try to
know whether different delivery ways of public health interventions are
effective [4]. May I suggest the inclusion of this issue as part of the
scientific program of the 3rd International Conference of EBM Teachers?.
Will it be possible to put together EBM champions involved in the care of
individual patients with concerned public health researchers and policy
makers that are looking for more sound scientific base on which to make
decisions that will affect the lives of millions?. I invite you to take a
look at the Child Survival series and the Health Systems series published
in the Lancet in 2003 and 2004, respectively. They are a superb example of
ongoing efforts to construct an evidence-based health care at public
health level. We should build on those efforts.
References
1. Huicho L, Campos M, Rivera J, Guerrant RL. Fecal screening tests
in the approach to acute infectious diarrhea: a scientific overview.
Pediatr Infect Dis J 1996;15:486-94.
2. Huicho L, Campos-Sanchez M, Alamo C. Metaanalysis of urine screening
tests for determining the risk of urinary tract infection in children.
Pediatr Infect Dis J 2002;21:1-11.
3. Devillé WL, Buntinx F, Bouter LM, Montori VM, de Cet HCW, vander Windt
AWM, Bezemer PD. Conducting systematic reviews of diagnostic studies:
didactic guidelines. BMC Med Res Methodol 2002; 2: 9.
4. Victora CG, Habicht JP, Bryce J. Evidence-based public health: Moving
beyond randomized controlled trials. Am J Publ Health 2004;94:400-5.
5. Black RE, Morris SS, Bryce J. Where and why are 10 million children
dying every year?. Lancet 2003;361:2226-34.
6. Jones G, Steketee RW, Black RE, Bhutta ZA, Morris SS, and the Bellagio
Child Survival StudyGroup. How many child deaths can we prevent this year?
Lancet 2003; 362: 65–71.
7. Bryce J, el Arifeen S, Pariyo G, Lanata CF, Gwatkin D, Habicht JP, and
the
Multi-Country Evaluation of IMCI Study Group. Reducing child mortality:
can public health deliver? Lancet 2003; 362: 159–64.
I ran across your site concerning glucomine and sulphate knee cream. I took a cruise to Mexico and bought some cream there with glucomine and sulphate for 6.00. I am 65 and I have rheumatoid-osteoarthritis and am in pain
That cream worked for me but I cant find it anywhere here.
Can you help me find it please?
When RCTs are consistent across a variety of
populations and settings, we should feel more
secure about the applicability of the
intervention. If it works in low risk and high
risk, young and old, East and West, it will
probably work in my patient. However, as Puliyel
and Sreenivas point out, RCTs don't always agree,
and sometimes diverge widely. When that happens,
we would like to know why. It could be any of the
PI...
When RCTs are consistent across a variety of
populations and settings, we should feel more
secure about the applicability of the
intervention. If it works in low risk and high
risk, young and old, East and West, it will
probably work in my patient. However, as Puliyel
and Sreenivas point out, RCTs don't always agree,
and sometimes diverge widely. When that happens,
we would like to know why. It could be any of the
PICO elements: the populations studied, the way
the intervention is delivered (dose, vehicle,
route, timing, etc), the comparator and
background treatments, or when or how the
outcomes were measured.[1] Or it can be that the
PICOs are the same, but that some of the trials
are flawed (poor randomisation, poor followup,
non-blinding, etc) and some not, leading to
confounding by trial quality. Systematic (and
unsystematic!) reviews should look for such
differences, and if they occur use them as an
opportunity to learn more about when and why a
treatment works or does not. However, that
requires considerable care to separate out the
possible true and artefactual causes of apparent disagreement between studies.
The Editors
References
[1] Glasziou PP, Sanders SL. Investigating causes
of heterogeneity in systematic reviews. Stat Med. 2002;21:1503-11.
In response to the Editor's invitation calling for short items on EBM related issues, we would like you to consider this statistical problem for possible publication.
The double-blind Randomised Controlled Trial (RCT) is the basis of
good evidence based medicine because it eliminates problems of bias and
confounding. However systematic reviews show different RCTs arriving at
diametrically op...
In response to the Editor's invitation calling for short items on EBM related issues, we would like you to consider this statistical problem for possible publication.
The double-blind Randomised Controlled Trial (RCT) is the basis of
good evidence based medicine because it eliminates problems of bias and
confounding. However systematic reviews show different RCTs arriving at
diametrically opposite conclusions. The reason for this is that the
samples for the RCTs are drawn from different populations and it reflects
the truth in those various populations. This matter is often overlooked
when met-analysis is done. When RCTs are aggregated in a meta-analysis we
have to aggregate the populations they represent – not the sample sizes.
Large samples from small populations will get undue weightage otherwise.
Meta-analysis as done presently can be misleading and unreliable.
Looking at the effectiveness of actions for well-child care makes us
forget that paediatricians are specialists and not primary care givers in
our health care system.
Specialists are the best professionals to deal with pathology and complex
problematic health situations for children. I think that well child should
be followed by a family doctor, having time to do prevention by education
and screening....
Looking at the effectiveness of actions for well-child care makes us
forget that paediatricians are specialists and not primary care givers in
our health care system.
Specialists are the best professionals to deal with pathology and complex
problematic health situations for children. I think that well child should
be followed by a family doctor, having time to do prevention by education
and screening. The complementarity of the level of care would add to the
effectiveness of care.
We can use the same analogy in maternity care, using GP and midwives for
primary care (the normal), and using obstetricians/gynecologist for
pathology and high risk situations.
The recommended interventions should be supported by evidence but the
organisation of care itself should be supported by evidence too.
We agree with doctors Evans and Hadler that our clinical decision
rule[1] should be validated in another setting and that it should be shown
to cause more good than harm before it could be widely used. Our study was
a first step in the process of developing a predictive tool for the
occupational outcome of back pain. In a next phase of development, not
only should the rule be validated in a new group of...
We agree with doctors Evans and Hadler that our clinical decision
rule[1] should be validated in another setting and that it should be shown
to cause more good than harm before it could be widely used. Our study was
a first step in the process of developing a predictive tool for the
occupational outcome of back pain. In a next phase of development, not
only should the rule be validated in a new group of subjects, but it
should also be compared with the judgment of clinicians; a decision tool
that is no better than the clinician’s own judgment is of no interest. If
the tool adds significantly to the clinician’s judgment, then the impacts
of its systematic use could be further studied.[2]
Evans and Hadler are also right to be cautious about the performance
of the rule. However, it includes a subset of predictors selected among
more than 100 variables, several of which measured at baseline, 6 weeks
and 12 weeks. We are confident to have identified the best predictors. As
we have recognized ourselves in the paper, the rule is however far from
perfect. But in its appreciation, it is also very important to understand
the limitations of the methods that are currently available to quantify
the performance of our model: for example, because classical measures of
concurrent validity ask for dichotomous outcomes, we had to regroup the
outcome categories and this tended to dilute the performance of the rule.
The alternative approach of comparing each group with the “Success” group
would have resulted in much better indices of predictive validity, but
they would however have been artificial, since the physician always works
from the complete pool of patients. Again, the real test will come from
comparisons with the clinicians’ judgment.
We do not believe that “return to work in good health” is an
“unstable psychosocial construct”. It was clearly defined and is certainly
clinically important. In many instances, this is the kind of outcomes on
which the primary care physician is asked to give a prognosis. It is,
obviously, not easy to predict. Should we then abandon our efforts because
the task is too difficult?
The interpretation Evans and Hadler seem to give to our results, as
to the association of the patient’s “own premonition” with their future
status, is clearly flawed. In a predictive statistical approach as the one
we have used, there is no intent to identify causal associations and there
is no adjustment for confounders.[3] All that can be said about this
association is that this variable is one of the most useful to predict the
outcome. Why not use it then? Others have also found patients’ recovery
expectations to be strongly linked with different health outcomes.[4-7]
Finally, interpreting Figure 2 of the paper to say that the outcome
at 12 weeks had a predictive accuracy of >90% is, unfortunately, too
simple: at 12 weeks, only 52% of subjects were in the “Success” category.
Forty-eight percent were in the other categories, and there was a
difference of 7.3% in “Failures” between 12 weeks and 2 years. Given that
the largest part (>80%) of the costs of back pain comes from a small
minority (<10%) of patients, this is not trivial.
References
1. Dionne CE, Bourbonnais R, Frémont P, Rossignol M, Stock SR,
Larocque I. A clinical return-to-work rule for patients with back pain.
Cmaj 2005;172(12):1559-1567.
2. Laupacis A, Sekar N, Stiell IG. Clinical prediction rules. A
review and suggested modifications of methodological standards. Jama
1997;277(6):488-494.
4. Cole DC, Mondloch MV, Hogg-Johnson S. Listening to injured
workers: how recovery expectations predict outcomes--a prospective study.
Cmaj 2002;166(6):749-754.
5. Kalauokalani D, Cherkin DC, Sherman KJ, Koepsell TD, Deyo RA.
Lessons from a trial of acupuncture and massage for low back pain: patient
expectations and treatment effects. Spine 2001;26(13):1418-1424.
6. Kiyak HA, Vitaliano PP, Crinean J. Patients' expectations as
predictors of orthognathic surgery outcomes. Health Psychol 1988;7(3):251-
268.
7. Mondloch MV, Cole DC, Frank JW. Does how you do depend on how you
think you'll do? A systematic review of the evidence for a relation
between patients' recovery expectations and health outcomes. Cmaj
2001;165(2):174-179.
Re: editorial BMJ 5th April 2008 Volume 336 pages 729-30: Improving uptake of MMR vaccine - Recognising and targeting between population groups are the
priorities
Dear Editor,
In the editorial on improving uptake of MMR vaccine, no mention was made
of the parents who decline MMR vaccination on ethical grounds.
The rubella vaccine component of MMR is derived from an aborted human
fetal cell line. The Takah...
Re: editorial BMJ 5th April 2008 Volume 336 pages 729-30: Improving uptake of MMR vaccine - Recognising and targeting between population groups are the
priorities
Dear Editor,
In the editorial on improving uptake of MMR vaccine, no mention was made
of the parents who decline MMR vaccination on ethical grounds.
The rubella vaccine component of MMR is derived from an aborted human
fetal cell line. The Takahasi rubella vaccine is a safe and effective
alternative. It is extremely difficult to access the Takahasi rubella
vaccine, grown on animal cell lines, due to import licence
restrictions. (Measles and mumps vaccines are not grown on aborted human
fetal cell lines. For those who can afford them, it is still possible to
have separate immunisations against measles and mumps.)
To achieve the goal of 95% immunisation several strategies should be
employed which also recognise diversity in the population. In 1994,Kenneth
Calman, then Health Minister, promised the Joint Faith Committee that an
ethical vaccine would be made available. However,as noted previously,
access to an ethical rubella vaccine has been made even more difficult.
Only coercive strategies to improve
completion of immunisation were mentioned in the article and the term
'..require legislative action..' (Ref 12) was used.
Are we now facing compulsory vaccination?
Ref 12 SalmonDA, TeretSP, MacIntyreCR, SalisburyD, BurgessMA,
Halsey NA. Compulsory vaccination and conscientious or philosophical exemptions:past present and future. Lancet 2006;367:436-42.
This is indeed an important finding on several levels, yet it remains
difficult in
translating this into clinical practice. I have found myself even more
ambivalent about suggesting SMBG to patients reasonably well-controlled on oral anti-diabetes medications.
In an effort to translate these findings, I propose the following
practical
suggestions.
1. For patients struggling to comply with health care...
This is indeed an important finding on several levels, yet it remains
difficult in
translating this into clinical practice. I have found myself even more
ambivalent about suggesting SMBG to patients reasonably well-controlled on oral anti-diabetes medications.
In an effort to translate these findings, I propose the following
practical
suggestions.
1. For patients struggling to comply with health care
recommendations, we
now know that SMBG does not need to be as high a priority in our
counseling.
2. For patients struggling to afford all the components necessary to
actually
perform SMBG (e.g., glucometer, strips, lancets), this now becomes an area
of
potential cost savings. Freeing up their limited discretionary income
might
allow them to afford a nutrition consultation, important medications or
other
expensive interventions with better evidentiary support.
3. For patients fully complying with SMBG, this might be a time to
allow them
to check their BG less frequently (e.g., Tuesday and Friday, fasting and
post-prandial, and prn for signs and symptoms of hypoglycemia and/or
hyperglycemia) instead of at their current rate.
Finally, since there is potential to have a critical study in the
future overturn
these recommendations, I am choosing to use caution both in how I explain
this study and in discontinuing anyone from SMBG.
Dear Editor
Shouldn't the RCT be done in such a way that the placebo also has Camphor and peppermint oil in identical concentration to the actual cream?[1] It is already known that the latter two can have a good effect on osteoarthritis, especially in the elderly.
Reference
1. Reginster J-Y. A topical cream containing glucosamine and chondroitin sulphate reduced joint pain in osteoarthritis of...
I see many results in which potassium falls (a little) above the normal range.[1] I was wondering at what level I should be concerned about sudden death being the presenting symptom.
I reflected that the context in which the result was found affects my decision making.
A routine test which identifies a raised value, is less alarming than a test which is done for a reason, such as the presence of s...
Dear Editor,
I read with optimism the note from Dr. Glasziou. It is encouraging to know that systematic reviews on diagnostic tests are being considered as part of national Cochrane movements. We badly need them. We have been involved in this task ever since 1995 and published two systematic reviews [1,2]. Quality of primary studies and methodological problems need to be studied and new tools need to be developed....
I ran across your site concerning glucomine and sulphate knee cream. I took a cruise to Mexico and bought some cream there with glucomine and sulphate for 6.00. I am 65 and I have rheumatoid-osteoarthritis and am in pain
That cream worked for me but I cant find it anywhere here. Can you help me find it please?
Thank you,
Peggy
When RCTs are consistent across a variety of populations and settings, we should feel more secure about the applicability of the intervention. If it works in low risk and high risk, young and old, East and West, it will probably work in my patient. However, as Puliyel and Sreenivas point out, RCTs don't always agree, and sometimes diverge widely. When that happens, we would like to know why. It could be any of the PI...
Dear Editor,
In response to the Editor's invitation calling for short items on EBM related issues, we would like you to consider this statistical problem for possible publication.
The double-blind Randomised Controlled Trial (RCT) is the basis of good evidence based medicine because it eliminates problems of bias and confounding. However systematic reviews show different RCTs arriving at diametrically op...
Dear Editor,
Looking at the effectiveness of actions for well-child care makes us forget that paediatricians are specialists and not primary care givers in our health care system. Specialists are the best professionals to deal with pathology and complex problematic health situations for children. I think that well child should be followed by a family doctor, having time to do prevention by education and screening....
Dear Editor,
We agree with doctors Evans and Hadler that our clinical decision rule[1] should be validated in another setting and that it should be shown to cause more good than harm before it could be widely used. Our study was a first step in the process of developing a predictive tool for the occupational outcome of back pain. In a next phase of development, not only should the rule be validated in a new group of...
Re: editorial BMJ 5th April 2008 Volume 336 pages 729-30: Improving uptake of MMR vaccine - Recognising and targeting between population groups are the priorities
Dear Editor,
In the editorial on improving uptake of MMR vaccine, no mention was made of the parents who decline MMR vaccination on ethical grounds. The rubella vaccine component of MMR is derived from an aborted human fetal cell line. The Takah...
This is indeed an important finding on several levels, yet it remains difficult in translating this into clinical practice. I have found myself even more ambivalent about suggesting SMBG to patients reasonably well-controlled on oral anti-diabetes medications.
In an effort to translate these findings, I propose the following practical suggestions.
1. For patients struggling to comply with health care...
Pages