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
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.
The paper in question has a strange problem: the definition of
cervicogenic headache. Reading the text, one must look to all headaches
that origins itself in cervical region, and there we have a conflict with
International Classification of Headaches: first described by Ottar
Sjaastad in late 1970s, the most correct assumption of cervicogenic headache
is a particular syndrome who origins the pain in C...
The paper in question has a strange problem: the definition of
cervicogenic headache. Reading the text, one must look to all headaches
that origins itself in cervical region, and there we have a conflict with
International Classification of Headaches: first described by Ottar
Sjaastad in late 1970s, the most correct assumption of cervicogenic headache
is a particular syndrome who origins the pain in C2 roots and have a
special pathopshisiology - this type of headache can also be classified
by indomethcacin-responsive headaches, and this fact is a dramatic one in
regard to the mechanisms envolved,particularly one certain pathway of
prostaglandins. Perhaps the cervicogenic headache has good results with
COX2 new drugs, but there are not therapeutics results with other
NSAIDs.The finest thing is the correct propedeutics of C2, the
neurological examination and not the ancillary ones.
At this paper results a doubt, at least, that the author is naming
cervicogenic headaches at all pain with some kind of relation with the
cervical spine, or the syndrome specially described and included in the
International Classification of Headaches: the last situation don’t have a
good chance to be analyzed…
Because of these facts, the results couldn’t be analyzed properly,
especially in view of evidence based medicine: we don’t know the nosology
of the cases presented.
The more appropriate approach to these is first the correct
nomination of the pain and, thus, the results of physical and/or
medication measures.
In a short resume, this paper does not fulfill the criteria to be
looked by the evidence medicine eyes.
In our primary care practice we are grappling with the diagnostic criteria for (type II) DM.
We use FPG as our main investigation with the WHO criteria of FPG <7.0 on two occasions defining diabetes.
In the event of repeated FPGs between 6 and 7 (& presumably a previous RPG 7-11.1) we have previously referred patients for an OGTT. However, we have found that this often does not lead to...
In our primary care practice we are grappling with the diagnostic criteria for (type II) DM.
We use FPG as our main investigation with the WHO criteria of FPG <7.0 on two occasions defining diabetes.
In the event of repeated FPGs between 6 and 7 (& presumably a previous RPG 7-11.1) we have previously referred patients for an OGTT. However, we have found that this often does not lead to a more definite diagnosis either.
Recently, we have considered using HBA1C as a second-line test in this group (RPG 6-7 x 2).
The local target HbA1C is 7.0.
Hence if HBA1C is < 7 we are reassured that such patients do not require medication and we offer lifestyle advice (and annual recall for re-testing).
In effect we are using FPG <7 (but >6) + HBA1C <7 to rule out diabetes, and this seems pragmatic since we would not wish to medicate this group unecessarily.
In the event that HBA1C is <7 we would presumably consider an OGTT or treat based on HBA1c alone (with metformin), this hasn't happened as yet.
This Cochrane review concluded that antibiotics reduce short to
medium-term persistence in children with persistent nasal discharge or
older children with radiographically confirmed sinusitis.
The EBM synopsis concluded that antibiotics are more effective than
placebo in children with persistent nasal discharge.
The 6 RCTs reviewed in the Cochrane review include four RCTs of older
ch...
This Cochrane review concluded that antibiotics reduce short to
medium-term persistence in children with persistent nasal discharge or
older children with radiographically confirmed sinusitis.
The EBM synopsis concluded that antibiotics are more effective than
placebo in children with persistent nasal discharge.
The 6 RCTs reviewed in the Cochrane review include four RCTs of older
children with radiographically confirmed sinusitis and two RCTs of children
with peristent nasal discharege (and no radiographic inclusion criteria).
The four RCTs with radiographic inclusion criteria found a benefit for
antibiotics.
Of the two RCTs of children with persistent symptoms (without
radiographic evaluation, i.e. the more common presentation in practice),
one had 188 patients and the other had only 13 patients. The RCT with 188
patients did not find any benefit for antibiotics, despite being funded by
the pharmaceutical company.
The data suggest that antibiotics would be helpful in children with
radiographically confirmed sinusitis (although this is not sufficient data
to show that radiogrpahic studies are warranted to find this subgroup),
BUT antibiotics for unselected children with persistent sinusitis symptoms
are not effective.
For those who like analogies, apples (representing studies of
children with persistent symptoms) were found to be rotten, while oranges
(representing studies of children with radiographic sinusitis) were found
to be healthy.
The Cochrane review combined apples and oranges. Since oranges
outnumbered apples more than two to one, the overall conclusion was
favorable and found that apples and oranges are healthy--without making
separate conclusions.
The EBM summary concluded that apples are healthy. However, the data still suggests that apples are rotten and oranges are
healthy.
I found this article interesting on the debate whether the benfit of
wearing elasticated stockings on long haul flights were useful in
prevention of DVT's in passengers. As you questioned the small amount used
in the study were not significant therefore inconclusive on
recommendations.
I was wondering how the staff, namely the pilots cope who make more
regular long haul flights than the passeng...
I found this article interesting on the debate whether the benfit of
wearing elasticated stockings on long haul flights were useful in
prevention of DVT's in passengers. As you questioned the small amount used
in the study were not significant therefore inconclusive on
recommendations.
I was wondering how the staff, namely the pilots cope who make more
regular long haul flights than the passengers . How do they prevent the
risks of DVT's. As we don't read about them in the press unlike if a
passenger aquires a DVT.
Regarding the article by Michael B Aldous,[1] I was little concerned about the impression I got from the randomized control trial. I ask them to consider the proven fact that immediate hearing improvement that takes place following placement of ventilatory tubes.
Is it not a fact that fluid accumaulation in middle ear results in
profound hearing loss? Does the modern formulas calculating significance and po...
Regarding the article by Michael B Aldous,[1] I was little concerned about the impression I got from the randomized control trial. I ask them to consider the proven fact that immediate hearing improvement that takes place following placement of ventilatory tubes.
Is it not a fact that fluid accumaulation in middle ear results in
profound hearing loss? Does the modern formulas calculating significance and power
of studies simply override the facts and figures.
Reference
(1) MB Aldous. Ventilation tubes did not improve quality of life in persistent otitis media with effusion
Evid Based Med 2001; 6:121.
The question asked in a recent article[1] was “In children with acute
respiratory infection, is tachypnoea accurate for detecting pneumonia?”
The answer obtained was “in children with acute respiratory infection,
tachypnoea had a sensitivity of 74% and specificity of 67%”. Please note
that radiographic determination of pneumonia was the reference standard to
which the finding of tachypnoea was compar...
The question asked in a recent article[1] was “In children with acute
respiratory infection, is tachypnoea accurate for detecting pneumonia?”
The answer obtained was “in children with acute respiratory infection,
tachypnoea had a sensitivity of 74% and specificity of 67%”. Please note
that radiographic determination of pneumonia was the reference standard to
which the finding of tachypnoea was compared.
Radiology has often been used as a “gold-standard” for the diagnosis
of pneumonia. But, is there enough evidence that a Chest X ray is
beneficial in the management of lower respiratory tract infections,
especially in non hospitalised children?
The WHO has advocated an Integrated Management of Childhood Illness
programme in which chest X-ray does not feature in the investigational
aids for the diagnosis of pneumonia. The recent British Thoracic Society
guidelines also suggest “If clinical signs are present, x ray examination
is not necessary to diagnose pneumonia”. [2]
A recent Cochrane systematic review also states, "There is no evidence
that chest radiography improves outcome in ambulatory children with acute
lower respiratory infection. The findings do not exclude a potential
effect of radiography, but the potential benefit needs to be balanced
against the hazards and expense of chest radiography."[3]
It was not very clear how many children in the study were treated as out-
patients. We should judge before we request chest X rays in non-
hospitalised children in this scenario. There are not only biomedical
hazards, but also cost factors where resources are limited.
The other question to ask is with the high mortality and morbidity
associated with acute lower respiratory infections in the developing
countries, is the negative predictive value of the study clinically
acceptable?
References:
(1) Palafox M, Guiscafré H, Reyes H, et al. Diagnostic value of tachypnoea
in pneumonia defined radiologically. Arch Dis Child 2000 Jan;82:41–5
(2) Russell G. Community acquired pneumonia. Arch. Dis. Child. 2001 85:
445-446
(3) Swingler GH, Zwarenstein M. Chest radiograph in acute respiratory
infections in children (Cochrane Review). In: The Cochrane Library, Issue
1, 2002.
Many thanks for your eLetter regarding an abstract appearing in both EBM[1] and EBN[2] with different commentaries. In answer to your queries:
First, when we have the same abstract appearing in both journals we do sometimes use the same commentary as well, however, if we think it doesn't fit our target audience we can require a fresh commentary. The risk is that, like all opinion, diff...
Many thanks for your eLetter regarding an abstract appearing in both EBM[1] and EBN[2] with different commentaries. In answer to your queries:
First, when we have the same abstract appearing in both journals we do sometimes use the same commentary as well, however, if we think it doesn't fit our target audience we can require a fresh commentary. The risk is that, like all opinion, differences in interpretation will occur, hiding such differences would not be our preference. The reason why we provide the details that we do in the abstract is so the reader can judge for
themselves - this is not only a matter of methods of the study, but also local context. Part of the context here is professional perspective. We did have considerable discussion over this particular article because some details such as the precise interventions were not well described in the paper, though Dr Robertson was helpful in supplying these.
Having said this, there isn't much difference in the commentaries, if you look at both of them in toto. They don't in fact disagree. John Robbins isn't saying that nurses can't play an important role in a home-based program for preventing falls, and Nancy Edwards isn't saying that this study is definitive for showing that nurses can only do it, or that the effect will be sustained if they do do it. That the two commentators are taking a somewhat different slant on their interpretations of the application of the results is valid, based on their perspectives.
Second, regarding your suggestion on joint commentaries; having multidisciplinary perspectives presented for each articles would be interesting and potentially informative. But, unfortunately we have to take into consideration obstacles such as the increase in editorial time it would take to prepare a multidisciplinary commentary and the amount of space such text would require. We would need more space for such discourse and would then have less space for other research. The research reports are the "stars" of the publication, so this could be a poor trade-off.
Finally thank you for suggesting this discourse be mounted on the eLetters page, we are keen to get more discussion going on both the websites but we do rely somewhat on our readers prompting appropriate topics.
I hope this answers all your queries.
Yours Sincerely
The Editors
References
(1) Robbins JA, Robertson MC, Campbell AJ (commentator). A home-based, nurse-delivered exercise programme reduced falls and serious injuries in people ³ 80
years of age. Evid Based Med 2001;6:182.
(2) Edwards N. A home based, nurse delivered exercise programme reduced falls and serious injuries in people 80
years of age. Evid Based Nurs 2002;5:22.
The study:
A home-based, nurse-delivered exercise programme reduced falls and serious injuries in people ³ 80 years of age. Robertson et al.
Effectiveness and economic evaluation of a nurse delivered home exercise
programme to prevent falls. 1: randomised controlled trial. [1]
appeared in both Evidence-Based Medicine [2] and in Evidence-Based Nursing.[3]...
The study:
A home-based, nurse-delivered exercise programme reduced falls and serious injuries in people ³ 80 years of age. Robertson et al.
Effectiveness and economic evaluation of a nurse delivered home exercise
programme to prevent falls. 1: randomised controlled trial. [1]
appeared in both Evidence-Based Medicine [2] and in Evidence-Based Nursing.[3]
The commentators differ in their perceptions of this paper. Edwards states that "Study results are promising and suggest that nurses have an important role to play in the
promotion of appropriate exercise that targets fall prevention among seniors."
Whereas Robbins believes "We can be less sure from this study what the actual "treatment" needs to be and who should provide it."
For me several issues are raised:
·Is it necessary to replicate
summaries of studies in both
journals, it seems wasteful of
resources
·What about the possibility of
joint (multidisciplinary)
commentaries
·The eLetters section where issues
such as those I have raised could
be aired still contains no letters
John Platt
References
(1) A home-based, nurse-delivered exercise programme reduced falls and serious injuries in people ³ 80 years of age Robertson MC, Devlin N, Gardner MM, et al.
Effectiveness and economic evaluation of a nurse delivered home exercise
programme to prevent falls. 1: randomised controlled trial. BMJ 2001 Mar 24;322:697-701.
(2) Robbins JA, Robertson MC, Campbell AJ (commentator). A home-based, nurse-delivered exercise programme reduced falls and serious injuries in people ³ 80
years of age. Evid Based Med 2001;6:182.
(3) Edwards N. A home based, nurse delivered exercise programme reduced falls and serious injuries in people 80
years of age. Evid Based Nurs 2002;5:22.
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
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...
Dear Editor
The paper in question has a strange problem: the definition of cervicogenic headache. Reading the text, one must look to all headaches that origins itself in cervical region, and there we have a conflict with International Classification of Headaches: first described by Ottar Sjaastad in late 1970s, the most correct assumption of cervicogenic headache is a particular syndrome who origins the pain in C...
Dear Editor
In our primary care practice we are grappling with the diagnostic criteria for (type II) DM.
We use FPG as our main investigation with the WHO criteria of FPG <7.0 on two occasions defining diabetes.
In the event of repeated FPGs between 6 and 7 (& presumably a previous RPG 7-11.1) we have previously referred patients for an OGTT. However, we have found that this often does not lead to...
Dear Editors
This Cochrane review concluded that antibiotics reduce short to medium-term persistence in children with persistent nasal discharge or older children with radiographically confirmed sinusitis.
The EBM synopsis concluded that antibiotics are more effective than placebo in children with persistent nasal discharge.
The 6 RCTs reviewed in the Cochrane review include four RCTs of older ch...
Dear Editor
I found this article interesting on the debate whether the benfit of wearing elasticated stockings on long haul flights were useful in prevention of DVT's in passengers. As you questioned the small amount used in the study were not significant therefore inconclusive on recommendations.
I was wondering how the staff, namely the pilots cope who make more regular long haul flights than the passeng...
Dear Editor
Regarding the article by Michael B Aldous,[1] I was little concerned about the impression I got from the randomized control trial. I ask them to consider the proven fact that immediate hearing improvement that takes place following placement of ventilatory tubes. Is it not a fact that fluid accumaulation in middle ear results in profound hearing loss? Does the modern formulas calculating significance and po...
Dear Editor
The question asked in a recent article[1] was “In children with acute respiratory infection, is tachypnoea accurate for detecting pneumonia?” The answer obtained was “in children with acute respiratory infection, tachypnoea had a sensitivity of 74% and specificity of 67%”. Please note that radiographic determination of pneumonia was the reference standard to which the finding of tachypnoea was compar...
Dear Mr Platt
Many thanks for your eLetter regarding an abstract appearing in both EBM[1] and EBN[2] with different commentaries. In answer to your queries:
First, when we have the same abstract appearing in both journals we do sometimes use the same commentary as well, however, if we think it doesn't fit our target audience we can require a fresh commentary. The risk is that, like all opinion, diff...
Dear Editors
The study:
A home-based, nurse-delivered exercise programme reduced falls and serious injuries in people ³ 80 years of age. Robertson et al. Effectiveness and economic evaluation of a nurse delivered home exercise programme to prevent falls. 1: randomised controlled trial. [1]
appeared in both Evidence-Based Medicine [2] and in Evidence-Based Nursing.[3]...