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Recent eLetters

Displaying 1-10 letters out of 50 published

  1. Judging evidence in postoperative analgesia

    Dear Editor,

    First, thank you for highlighting our paper. However, I do want to take issue with this commentary.

    Systematic reviews in postop analgesia have been done now for over 20 years, and there is considerable methodological research to substantiate what is done. The results are robust and trustworthy.

    Single trials, however well done, are not trustworthy because while they may be powered to show direction of effect (drug better than placebo, for example), they are not powered to measure the magnitude of effect accurately. That typically needs about 10 times more data, hence the value of systematic reviews and overview reviews (see Cochrane Database Syst Rev. 2015 Sep 28;9:CD008659). Overview reviews are where you can get indirect comparison of efficacy.

    I think the authors are making a point about speed of onset with caffeine, and that is fair, though it took some time to work that out. And if so I am not sure that the study by Raisian helps. Apart from being small (fewer than 40 per treatment group), it was a multiple-dose study in patients who did not have initial moderate to severe pain, so it was more of a pre-emptive study than one that could measure speed of onset.

    Conflict of Interest:

    I am an author of the paper commented upon.

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  2. 'Cognitive biases plus' and healthcare evidence

    Dear Editor,

    Mazar and Ariely's recent paper [1] reinforces the concepts and suggestions discussed in our recent publications: dishonesty is a human universal, and there is no one-size-fits-all solution [2,3]. Education, moral reminders and changing how researchers are rewarded are important tools [1]. Most importantly, we need to reclaim the integrity, dedication and code of honor Sir Austin Bradford Hill considered essential to the practice of Medicine [4].

    References

    1. Mazar N, Ariely D. Dishonesty in scientific research. J Clin Invest 2015; Nov 2; 125(11):3993-6.

    2. Seshia SS, Makhinson M, Phillips DF, Young GB. Evidence-informed person -centered healthcare part I: do 'cognitive biases plus' at organizational levels influence quality of evidence?. J Eval Clin Pract 2014; Dec;20(6):734-47.

    3. Seshia SS, Makhinson M, Young GB. 'Cognitive biases plus': covert subverters of healthcare evidence. Evid Based Med 2015; Nov 26;. doi: 10.1136/ebmed-2015- 110302.[Epub ahead of print].

    4. Hill AB. Medical ethics and controlled trials. Br Med J 1963; Apr 20;1(5337):1043-9.

    Conflict of Interest:

    None except intellectual

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  3. Re:Inaccurate radiation exposure calculation

    Dear Editor,

    You are correct that protocols and improved technology have led to reductions in radiation exposure from CT scanning at some hospitals. I would suggest though that the resultant reduction in the risk of fatal cancer due to imaging does not affect the conclsion of the paper. If a laparotomy on a healthy young patient carries no risk of death and CT scanning imposes a risk of death the decision to perform a CT scan on a young healthy person before proceeding to the operating room poses an ethical dilemma for the ordering physican.

    Conflict of Interest:

    None declared

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  4. Inaccurate radiation exposure calculation

    Dear Editor,

    Dr Rogers et al have astutely pointed out the dangers of routine CT assessment of right iliac fossa pain in the paediatric population. I agree wholeheartedly that the role of clinical judgement, alongside observation and serial examination remain critical. Ultrasonography and MRI are additional valuable diagnostic adjuncts that do not incur a radiation dose to patients.

    I would question the data the authors have used to calculate the risk of CT induced cancer. The estimates from the BEIR V data are based on a radiation exposure of 10mSv. Contemporary CT-appendix protocols expose patients to around 2mSv or less, but have equivalent accuracy to a CT scan of the abdomen and pelvis. Would it not be more appropriate to calculate the risk of cancer based on these figures?

    Conflict of Interest:

    None declared

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  5. Maternal pertussis vaccination

    Dear Editor,

    We were pleased to read the commentary by Millar and Sanz(1) regarding our publication on Tdap safety in pregnancy from the Vaccine Safety Datalink.(2) We agree that policies regarding routine vaccination should be made after careful review of the risks and benefits of vaccination. For maternal vaccination, evaluations of risk-benefit profiles are complex, as both maternal and infant outcomes must be considered.

    In our observational retrospective study of more than 25,000 women with singleton pregnancies who received Tdap during pregnancy in California, we found no increased risk of hypertensive disorders of pregnancy, preterm or small for gestational age births associated with maternal vaccination. We did observe a small, but statistically significant increased risk of chorioamnionitis diagnosis among vaccinated women. Chart review of a subset of women with a chorioamnionitis diagnosis revealed that only half met case definitions for probable chorioamnionitis. Furthermore, 95% of women with a chorioamnionitis diagnosis had an epidural during labor, providing a potential alternative explanation for fever during labor.(3)

    Tdap vaccination during pregnancy remains the most effective available strategy for promoting maternal transfer of pertussis-specific antibodies and thus preventing severe disease in newborns. In a recent case-control study in England, Dabrera and colleagues estimated the effectiveness of maternal Tdap vaccination for preventing laboratory- confirmed pertussis infection in infants to be 91%.(4)

    In the United States, policies to routinely administer Tdap during pregnancy came after widespread pertussis outbreaks, including 10 infant deaths in California.(5) In 2014, California once again reported an increase in pertussis cases. In both recent outbreaks, disease prevalence and severity has been highest in infants under 4 months.(6) We agree with Millar and Sanz that further monitoring of Tdap safety is important, with particular attention to fetal outcomes potentially associated with chorioamnionitis. However, given continued ongoing pertussis transmission, and the high of risk of morbidity in newborns, we support current guidelines from the Advisory Committee on Immunization Practices recommending the routine administration of Tdap during pregnancy.

    References

    1. Millar MR, Sanz MG. The administration of pertussis vaccine to pregnancy women was associated with a small increased risk of chorioamnionitis, but not an increased risk fo hypertensive disorders or preterm birth Evid Based Med. 2015 (in press).

    2. Kharbanda EO, Vazquez-Benitez G, Lipkind HS, et al. Evaluation of the association of maternal pertussis vaccination with obstetric events and birth outcomes. JAMA 2014;312(18):1897-1904.

    3. Abramovici A, Szychowski JM, Biggio JR, et al. Epidural Use and Clinical Chorioamnionitis among Women Who Delivered Vaginally. Am J Perinatol. Apr 4 2014.

    4. Dabrera G, Amirthalingam G, Andrews N, et al. A case-control study to estimate the effectiveness of maternal pertussis vaccination in protecting newborn infants in England and wales, 2012-2013. Clin Infect Dis 2015;60(3):333-337.

    5. Winter K, Harriman K, Zipprich J, et al. California pertussis epidemic, 2010. J Pediatr 2012;161(6):1091-1096.

    6. Winter K, Glaser C, Watt J, Harriman K. Pertussis Epidemic - California, 2014. Morbid Mortal Wkly Rep. 2014;63(48):1129-1132.

    Conflict of Interest:

    None declared

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  6. Re:Further research in low dose CT scan for suspected appendicitis.

    We share your enthusiasm for the current efforts to reduce radiation exposure associated with the use of CT scanning and agree with your assertion that performance of appendectomy without scanning will inevitably lead to more negative appendectomies. We are confident though based on the NHS laparoscopic appendectomy statistics reviewed by Omar and Clark in the Annals of Surgery that those negative appendectomies are associated with essentially no risk. In the NHS series 234,402 patients underwent laparoscopic appendectoy without a single death or major morbidity. CT scanning these 234 thousand patients on the other hand will cause more than 100 fatal cases of cancer.

    Conflict of Interest:

    None declared

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  7. Further research in low dose CT scan for suspected appendicitis.

    Dear Editor,

    We read with great interest the recent article written by William Rogers et al on the Harms of CT scanning prior to surgery for suspected appendicitis(1). It highlights the radiation risk of cancer while routinely performing an abdominal CT scan on an otherwise healthy patient with symptoms suggestive of appendicitis. This radiation risk of cancer becomes all the more important in patients with 'negative' appendectomy.

    However, relying purely on clinical judgment for diagnosis of appendicitis can result either in increased 'negative' appendectomy or diagnostic delay which may cause appendiceal perforation. There are studies which show that negative appendectomy is associated with an appreciable degree of morbidity and mortality, including a significant increase in length of hospital stay, postoperative complications like wound infection and death(2). Also, it can increase health care costs. Perforated appendicitis is also related to increase in length of hospital stay(3). In-house mortality is high for perforated appendicitis(4).

    During the last decade, there have been many advances in CT technology which have resulted in improved spatial resolution, rapid scan and increased use of multiplanar images enabling better visualization of appendix. Although the effective dose value for CT scan of abdomen and pelvis is taken as 8 - 11 mSv(5) , studies comparing low-dose CT group with standard-dose CT group have shown that low-dose CT was not inferior with regard to diagnosis of appendicitis(6) and negative appendectomy rates(7) . Neither the appendiceal perforation rate nor the diagnostic performance of CT for appendicitis differed significantly between the two groups. A randomized controlled trial, low-dose CT for appendicitis trial (LOCAT) is being undergone comparing the clinical outcomes following low vs standard-dose computed tomography as the first-line imaging test in adolescents and young adults with suspected acute appendicitis, where the effective dose of CT is reduced to 2 mSv(8). This greatly reduces the carcinogenic risk. Study using non-contrast focused abdominal CT scan has also shown to have a high sensitivity for diagnosis of appendicitis(9). Here, there is no risk of contrast nephropathy.

    Further research in this field will enable us to use very low dose CT scan with significantly less radiation risk of cancer; at the same time significantly reducing negative appendectomy rate without an increase in the appendiceal perforation rate.

    References

    (1) Rogers, W., Hoffman, J., Noori, N. Harms of CT scanning prior to surgery for suspected appendicitis. Evidence Based Medicine 2015;20(1):3-4.

    (2) Flum DR, Koepsell T. The clinical and economic correlates of misdiagnosed appendicitis: nationwide analysis. Arch Surg 2002;137:799-804.

    (3) Al-Omran M, Mamdani M, McLeod RS. Epidemiologic features of acute appendicitis in Ontario, Canada. Can J Surg 2003;46:263-268.

    (4) Wen SW, Naylor CD. Diagnostic accuracy and short-term surgical outcomes in cases of suspected acute appendicitis. CMAJ 1995;152:1617-1626.

    (5) Furlow B. Radiation dose in computed tomography. Radiol Technol 2010;81:437-50.

    (6) Keyzer, C., Tack, D., De Maertelaer, V., et al. Acute Appendicitis: Comparison of Low- Dose and Standard-Dose Unenhanced Multi-Detector Row CT 1. Radiology 2004;232(1):164-172.

    (7) Kim, K., Kim, Y. H., Kim, S. Y., et al. (2012). Low-dose abdominal CT for evaluating suspected appendicitis. New England Journal of Medicine 2012;366(17):1596-1605.

    (8) Ahn S. LOCAT (low-dose computed tomography for appendicitis trial) comparing clinical outcomes following low- vs standard-dose computed tomography as the first-line imaging test in adolescents and young adults with suspected acute appendicitis: study protocol for a randomized controlled trial.Trials. 2014;15:28. doi:10.1186/1745-6215-15-28.

    (9) Akhtar, W., Ali, S., Arshad, M., Ali, F., Nadeem, N. (2011). Focused abdominal CT scan for acute appendicitis in children: can it help in need. Journal of the Pakistan Medical Association 2011; 61(5):474-6.

    Conflict of Interest:

    None declared

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  8. In Response to Windish D. "EBM apps that help you search for answers to your clinical questions."

    Dear Editor,

    We read with great interest the recent article by Dr. Windish [1] reviewing a number of Evidence-Based Medicine (EBM) smartphone apps. Immediate access to brief summaries of the literature is essential in bringing EBM knowledge to the bedside, as physicians are often busy and are presented with frequent interruptions which hinder their ability to perform detailed searches or read complete articles during the workday. Indeed, we note the success of the randomized trial by Pastori, et al. [2], where in the intervention group they provided a physician whose sole purpose was collecting relevant EBM evidence from the literature. This resulted in better patient outcomes, as assessed by ICU transfers and hospital readmissions.
    We would like to highlight an EBM database of diagnostic accuracy that we have developed, entitled GetTheDiagnosis.org (http://www.getthediagnosis.org). This website, which has a mobile version suited to smartphones as well, contains a database of sensitivity and specificity of history questions, physical examination findings, and laboratory and imaging tests for nearly 300 diagnoses. The data is culled from primary literature and is maintained by physician-users, who can submit new entries or edit existing entries in the same manner as Wikipedia. The site displays citations and links to the literature for each entry, and the data is highly structured and allows for searching by diagnosis or finding. By using structured data, we can provide a post-test probability calculator based on the data for each diagnosis.
    In this way, we have attempted to marry successful features of apps such as EBM Tools or MedCalc 3000 EBM with an actual database of EBM data from the literature. We hope that physicians will find our website helpful and easy to use while in the clinic, and we hope that many of them will help build the database by adding articles from the primary literature.

    References

    1. Windish D. EBM apps that help you search for answers to your clinical questions. Evid Based Med 2014;:ebmed-2013-101623. doi:10.1136/eb-2013- 101623

    2. Pastori MM, Sarti M, Pons M, et al. Assessing the impact of bibliographical support on the quality of medical care in patients admitted to an internal medicine service: a prospective clinical, open, randomised two-arm parallel study. Evid Based Med 2014;19:163-8. doi:10.1136/ebmed-2014-110021

    Conflict of Interest:

    None declared

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  9. Opinion editorials: necessity of present times

    Dear Editor,

    This article brings into light the upcoming ways in which medical health care knowledge is disseminated between general population and the various pitfalls such an approach can have. Although such issues are in nascent stage in a developing country like India but its climbing up the ladder at a brisk rate. The new generation of physicians is media savvy but can get easily influenced by media based propaganda's.
    There is no doubt Evidence based Medicine is the future of way medicine is going to be practiced be it in a developed country or a developing nation, but scientific and regulating authorities need to keep a keen and watchful eye on ways, quality and standard of literature that is being published and distributed to practitioners and public.
    There needs to be a healthy and interactive communication between journalists and scholars so that the message intended reaches the public and students in a clear, concise and undisputed way.
    We agree with the authors that development of such web based facilities is an inevitable need of the hour even from the point of view of a developing country. Such acts will bring about greater understanding of complex medical issues and practices followed in patient care thereby avoiding unnecessary litigation and panic created by outbreak of an infectious diseases, a prime example being epidemic of dengue fever and assumption of direct correlation of decreasing platelet count with hemorrhage and mortality which is absolutely not true as shown by number of studies.
    The article brings about the required amalgamation of media and scientific community in a cohesive way to produce comprehensible medical knowledge and its dissemination in public domain.

    Conflict of Interest:

    None declared

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  10. Author's response

    Dear Editor,

    I am very grateful to Ken Uchino for amplifying and clarifying the detail of some of the points I was trying to make within the word limits of a 'Perspectives' paper. I suggest there are four key elements:

    1. The epidemiology is indeed complex and I am neither an academic nor an epidemiologist. However, it would appear that we can agree that there is indeed a difference between 'younger old' (i.e. 65-75) and 'older old' (i.e. 80+), both in relative and absolute risk - albeit in opposite directions. The key point here is not the strength of the associations with age, but the magnitude of impact of treating the risk factor at any given age. This is where interventional trials come in.

    2. As I pointed out in my paper, the data about treating hypertension in 80+ year olds accumulated prior to HYVET were very suggestive of benefit; they predicted HYVET would give a definitive answer. HYVET - by far the largest trial looking at patients aged 80+ - failed to live up to this promise. Sadly, the premature termination of the trial (because of excess mortality in the placebo group) arguably raised more questions about the clinical applicability of its results, than the trial answered.

    3. The PROSPER trial examined the use of statins in European patients initially aged 70-82 (mean 75), and followed up for an average of 3.2 years. Nearly 20% of patients entered into the 4-week single-blind placebo lead-in period failed to proceed to the randomised period (either for using <75% or more than 120% of placebo, or because they refused to participate). This raises questions as to generalisability. Whilst reducing cardiovascular events, the intervention failed to show a reduction in stroke. I fully accept that absence of evidence is not necessarily evidence of absence, but this must surely raise questions as to the magnitude of any true effect.

    4. None of these trials looked into the patients' preferences and priorities re outcomes. I argue that these change significantly with advancing frailty and incapacity (which in turn increase disproportionately with, but are not confined to, increasing age).

    If we cannot even be certain of the ostensibly simple quantitative aspect of the decision (the certainty of the magnitude of the treatment effects), how can we properly weigh that up against the much more difficult to define qualitative aspects (the beliefs, values, and priorities of my patient)?

    My central point is that without robust evidence applicable to the patient in front of me - usually over 80, and often very frail - how can I help the patient to reach truly informed consent? I may well have some of the estimates of magnitude wrong, but the principle still stands. A treatment decision is only as strong as its weakest link. I suggest that there are so many weak links in this particular evidence chain that it is almost impossible to reach a decision that all doctors would support. Suggesting that a simple 'one size fits all' (i.e. algorithmic guideline- based) solution would be appropriate is simplistic. Without more data we cannot be sure.

    For all these reasons I strongly urge that we undertake randomised trials of withdrawals of treatment in real life elderly patients (both frail and robust). This has the potential to find out how much impact these interventions have in clinical practice, as opposed to in the rarefied environment of scientific clinical trials.

    In the UK NHS we arguably should have a real opportunity to use 'big data' in real life in this way to find out if there are any signals there amongst the noise. A simple pragmatic trial involving tens of thousands of people would surely have a good chance of giving us the information we need? If the NHS funded this with the money currently earmarked for hitting treatment targets in those over 80, it would not take long to answer this question.

    Conflict of Interest:

    None declared

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