eLetters

353 e-Letters

  • Understanding NNTs

    Roe et al have written a useful article on the continuing misuse of relative risk, and the importance of understanding relative risk and absolute risk difference in injury risk outcomes in randomised controlled trials. In describing the Number Needed to Treat (NNT) they miss out an important word- the NNT is the number needed to treat to prevent one _extra_ adverse event, not to prevent a single adverse event. To see thus suppose the NNT was m. In their notation the risk in the intervention group is IG and the Control group is CG. The number of events expected in the intervention group if we treated m of them is mIG. To prevent one event we have mIG=1 and so we have to treat m=1/IG subjects to prevent one event. However we would expect mCG events in the control group. To prevent one _extra_ event in the intervention group we would require mCG-mIG =1 (assuming CG>IG) . Thus m=1/(CG-IG) which is the definition of the NNT. They could also, perhaps, have mentioned the problems in using the NNT, such as differing baselines leading to it being uninterpretable as described, for example by Stang, A., Poole, C., & Bender, R. (2010). Common problems related to the use of number needed to treat. Journal of Clinical Epidemiology, 63(8), 820–825

  • RE: Does leisure time physical activity protect against low back pain? Systematic review and meta-analysis of 36 prospective cohort studies

    Shiri et al. conducted a meta-analysis to examine the effect of leisure time physical activity on non-specific low back pain (LBP) (1). Adjusted risk ratio (RR) (95% confidence interval) of moderately/highly active individuals, moderately active individuals and highly active individuals against individuals without regular physical activity for frequent/chronic LBP was 0.89 (0.82 to 0.97), 0.86 (0.79 to 0.94) and 0.84 (0.75 to 0.93), respectively. For LBP in the past 1-12 months, adjusted RR did not reach the level of significance in any levels of physical activity. The authors concluded that leisure time physical activity might reduce the risk of chronic LBP by 11%-16%. I have some concerns about their study by presenting negative information regarding protection of LBP by physical activity.

    First, Saragiotto et al. conducted a meta-analysis on the effectiveness of motor control exercise (MCE) in patients with nonspecific LBP (2). MCE focuses on the activation of the deep trunk muscles and targets the restoration of control and coordination of these muscles. They concluded that MCE was probably more effective than a minimal intervention for reducing pain, but did not have an important effect on disability, in patients with chronic LBP. In addition, there was no clear difference between MCE and other forms of exercises or manual therapy for acute and chronic LBP. Although there is no definite information to recommend MCE for non-specific LBP, further studies are need...

    Show More
  • International Olympic Committee consensus statement: methods for recording and reporting of epidemiological data on injury and illness in sport 2020 (including STROBE Extension for Sport Injury and Illness Surveillance (STROBE-SIIS))

    Allow me to make use of the opportunity to extend my appreciation to the BJSM for being a publication of high standing, bringing cutting edge information to the sports medical fraternity.
    Thank you for the consensus statement of the International Olympic Committee describing the methods for recording and reporting of epidemiological data on injury and illness in sport 2020 (including STROBE Extension for Sport Injury and Illness Surveillance (STROBE-SIIS))”.[1] I found it both informative and useful.
    I have a comment about the use of the word “Nervous” in the first column of Table 5. It is an adjective whereas the rest of the words in the column are nouns that more accurately describe the tissue type under discussion. It is possibly only a linguistic error, but I am of the opinion that it should be “Nerve” or “Neural tissue”.

    Reference
    1. Bahr R, Clarsen B, Derman W, et al. International Olympic Committee consensus statement: methods for recording and reporting of epidemiological data on injury and illness in sport 2020 (including STROBE Extension for Sport Injury and Illness Surveillance (STROBE-SIIS)). Br J Sports Med Published Online First: 18 February 2020. doi: 10.1136/bjsports-2019-101969

  • Response to: “Potentially Biased Results on Mouthguard Use and Reduction of Concussion Risk”

    We read with interest, and concern, the letter submitted by Schilaty et al arguing bias in our analysis examining the association between concussion and mouthguard use. Schilaty et al argue that a nested case-control study was not optimal and that “Based on a relatively small cohort, a complete case-control study would have been more appropriate than a nested case-control study.” They then go on to argue that “selection criteria of the non-concussion group biased the study as a random sample was not selected from the remaining cohort (n=2,040)” eliminating “from the analysis all non-injured players who wore mouthguards.” Finally, Schilaty et al contend that our study did not “properly compare the incidence of concussion between wearers or non-wearers of mouthguards.” There are multiple concerning statements and assertions made by the authors of the letter, Schilaty et al., that we will address below.

    Shilaty et al discuss the desire to compare “incidence of concussion between wearers and non-wearers of mouthguards.” Incidence cannot truly be estimated from a case-control study, given that the number of cases and controls is fixed from the design. Rather, we are after the odds ratio based on the ratio of the odds of exposure in cases relative to controls (the odds ratio of exposure is mathematically the same as the odds ratio of being a case). Modern conceptualizations of the case-control study invoke the idea of pseudo frequencies or quasi-rates related to construc...

    Show More
  • Comment on "Three steps to changing the narrative about knee osteoarthritis: a call to action."

    Whilst its principal message is clear, I wish to draw attention to three problems arising from the editorial authored by Caneiro et al.:

    1. They say, “… pain is described as an altered state of a person’s knee health influenced by biopsychosocial factors, of which many can be modified.”

    How is “knee health” different from “whole person health”?

    Just how many biopsychosocial factors can be modified?

    2. Contemporary evidence is said to support the proposition that “knee health” is “influenced by the interaction of different biopsychosocial factors” that have the property of “modulating inflammatory processes and tissue sensitivity”.

    Is there any evidence that such an interaction actually takes place?

    And furthermore, what are the postulated mechanisms for such interaction?

    3. Their Infographic (“What should you know about knee osteoarthritis?”) contains the statement “rest and avoidance makes pain worse.” Presumably they are referring to avoidance of graded exercise. But even so, how do the authors justify their conclusion that avoidance of exercise or rest "per se" can “make pain worse”?

  • Response to “International Olympic Committee consensus statement: methods for recording and reporting of epidemiological data on injury and illness in sport 2020 (including STROBE Extension for Sport Injury and Illness Surveillance (STROBE-SIIS))

    We read with interest the recent International Olympic Committee consensus statement: methods for recording and reporting of epidemiological data on injury and illness in sport 2020 (including STROBE Extension for Sport Injury and Illness Surveillance (STROBE-SIIS))”.[1] While helping to clarify aspects associated with recording and reporting epidemiological data, based on the definitions included in the statement, we believe that some of the examples in Table 10 require clarification with regards to the recording of injuries and calculation of time loss.

    Consider the example for ‘Delayed’ time loss: Sunday injury, thigh contusion, able to train on Monday and Tuesday but unable to train on Wednesday and returns on Sunday (time loss starts on Wednesday even though the injury was on Sunday). Time loss (days) 3. Given the recommended reported time loss of 3-days, and definition provided whereby “time-loss days should be counted from the day after the onset that the athlete is unable to participate”, we assume Wednesday is considered as the day of onset (day 0), with subsequent impact on Thursday, Friday and Saturday resulting in a 3-day time-loss (days). When considering this example, we were then somewhat confused by the example for, ‘Intermittent’ time loss: boy with Osgood-Schlatter disease that gets reported at the start of a training camp on Monday. The player may train fully on Monday, Tuesday and Thursday, but miss training on Wednesday and Friday (time loss co...

    Show More
  • ASDMAC and DFSNZ support the call for TUE Committee peer review process

    The Australian Sports Drug Medical Advisory Committee (ASDMAC) and Drug Free Sport New Zealand (DFSNZ) Therapeutic Use Exemption (TUE) committees welcome the recent discussion paper by our esteemed colleague Dr Ken Fitch entitled "Therapeutic Use Exemptions (TUEs) are essential in sport: but there is room for improvement." As the national bodies responsible for TUE assessment and processing in our respective nations, ASDMAC and DFSNZ agree that the integrity of the TUE process is sound and essential, but could be improved through a peer review process.

    Although the World Anti-Doping Agency (WADA) does screen TUEs entered in Anti-Doping Administration and Managements System (ADAMS), the supplementary screening of TUE Committees themselves, including the members, their TUE processes and procedures, as suggested by Dr Fitch would improve the reliability and standardisation of TUEs. In 2018 and 2019, ASDMAC and DFSNZ with the support of the World Anti-Doping Agency (WADA) TUE expert group designed and conducted a TUE Peer Review Audit. This process included the documentation of the proposed audit process, followed by the respective visits of each Chair to the others TUEC meeting. During the visits the Chairs assessed a number of TUE applications and outcomes to ensure that those granted were done so in accordance with the WADA ISTUE and that the WADA Medical Information to Support TUEC decisions had been appropriately interpreted. These visits also includ...

    Show More
  • The Author of the Inflammation and Heart Disease Theory Cautions - Cholesterol and Saturated Fat are an Integral part of the Inflammatory process we call Coronary Artery Disease.

    In the mid-1990s, as one of the reviewers for the American Heart Association, the first author of this letter, Dr Richard M Fleming (RMF) introduced a then controversial theory stating that Coronary Artery Disease (CAD) is the result of an inflammatory process, which builds up within the walls of the arteries (Figure 1) impairing their ability to dilate and increase coronary blood flow when needed; thus producing regional blood flow differences resulting in angina [1-3] and ultimately myocardial infarction (MI) and death.
    In recent years, people promoting various dietary and lifestyle practices – particularly those promoting LowCarb-Keto diets, have taken advantage of the obesity epidemic and focused everyone’s attention on obesity and weight loss. These individuals have not determined the actual impact their diets have on CAD - which would require more than just looking at changes in weight or serum blood tests. It would require measurement of changes occurring within the walls of the coronary arteries themselves – not some other artery - and the resulting change in coronary artery function [1,4].
    These individuals, including Dr. Aseem Malhotra [5] support their dietary recommendations by showing weight loss, and occasionally reductions in cholesterol levels – at least initially in some people. Over the years as it has been shown that cholesterol levels fail to fall, and frequently increase on such diets, their argument has changed and has been replaced with “...

    Show More
  • Potentially Biased Results on Mouthguard Use and Reduction of Concussion Risk

    We read the referenced article by Chisholm et al.1 with keen interest. Concussions present a significant injury burden on the athletic community, especially among youth athletes who are more susceptible to potential long-term consequences.3,7,9 Concussion diagnosis and treatment are important, but prevention is key. Chisholm and colleagues present data on young athletes that supports a reduction in the risk of concussion with the use of a mouthguard. However, the authors admit that the current literature on mouthguards has methodological limitations and high risk of bias. The primary objective of their study was to examine the association between concussion and mouthguard use in youth ice hockey.

    We agree with the benefit players derive from wearing mouthguards to protect dentition and possibly reduce the incidence and/or severity of concussion during contact sports. However, we question the statistical methodology performed and the resultant conclusions of the manuscript. The authors utilized a nested case-control design to determine the risk of concussion with mouthguard use. Due to this design utilization, the results potentially present a high risk of bias that the authors were attempting to avoid. A nested case-control design compares incident cases nested in a cohort study with controls drawn at random from the rest of the cohort.2,6 Further, a nested case-control is useful for summarizing the trends observed in a large population when study of the e...

    Show More
  • Departmental Infographic Needed!

    As part of this excellent summary editorial, you mentioned how important it is to tailor your education to the needs and preferences of the patient. Therapists also have these diverse needs so it would be an excellent resource to have this in a graphical format that could be displayed openly in any department, whether it be in Outpatients or in physiotherapy for example as a visual reminder to clinicians but also visible for patients to interrogate so that they can have an understanding of what is to be expected in their consultation and by creating these expectations, will help to drive forward better, more holistic assessment and care of patients.

Pages