1230 e-Letters

  • Response to Pedersen's comment to our paper "Routine induction in late-term pregnancies: follow-up of a Danish induction of labour paradigm

    We appreciate the interest that Dr. Pedersen has shown in our paper, but he has apparently misunderstood some aspects of our analysis. In the analysis of the stillbirth data, we first described the dependence of log (rate) on calendar year by a straight line. Next, we allowed the slope to change from 2011 onwards (a so-called linear spline with a knot at 2011). This did not improve the fit significantly. This is the analysis reported in our paper. Besides we also tried to see if a change in intercept from 2011 onwards would lead to a significantly better fit. This was not the case. This latter model is the one that Dr. Pedersen considers, but this was not the one presented in our paper.

    We are also concerned about Dr. Pedersen’s suggestion that we have been unresponsive to his questions. We can document at least 11 email correspondences and two face to face meetings with Dr. Pedersen to accommodate Dr. Pedersen’s wish for more information and discussion of our analyses. These mails and meetings have also included the Lead Professor of Dr. Pedersen’s department and a Professor in Biostatistics from Aarhus University. The Professor in Biostatistics has confirmed to all included in the meetings and in the additional emails that our analysis as well as our conclusions in the paper were valid.

    Eva Rydahl, Eugene Declercq, Mette Juhl, Rikke Damkjær Maimburg

  • RE: Impact of disasters, including pandemics, on cardiometabolic outcomes across the life-course

    De Rubeis et al. conducted a systematic review to evaluate the effect of disasters, including pandemics, on cardiometabolic outcomes (1). Clinical outcomes were checked ≥1 month following the disaster. The effects of exposure to disaster during pregnancy/childhood and during adulthood were included, and increased cardiovascular disease incidence or mortality, diabetes and obesity were observed in each study. Although the biological mechanisms of the association might be complex, long-term effects of disasters on cardiometabolic health should be explored to elucidate prevention strategies against forthcoming disasters (2-4).

    1. e Rubeis V, Lee J, Anwer MS, et al. Impact of disasters, including pandemics, on cardiometabolic outcomes across the life-course: a systematic review. BMJ Open. 2021;11(5):e047152.
    2. Chua MWJ. Managing patients with obesity in the post COVID-19 world: Time to sharpen the saw. Obes Res Clin Pract. 2021;15:85-88.
    3. Narita K, Hoshide S, Tsoi K, et al. Disaster hypertension and cardiovascular events in disaster and COVID-19 pandemic. J Clin Hypertens (Greenwich). 2021 ;23(3):575-583.
    4. Burg MM, Soufer R. Post-traumatic Stress Disorder and Cardiovascular Disease. Curr Cardiol Rep. 2016;18(10):94

  • Re: Enabling healthcare staff to improve vaccine uptake

    Dear Dr. Walid Al-Wali et al,
    Thank you for interest in our work, particularly for your comments on the published protocol titled: Estimating the vaccine confidence levels among healthcare students and staff of a tertiary institution in South Africa.
    As you rightly observed, and as stated in the article, the study population is healthcare students and staff of a tertiary institution in South Africa. In this particular setting (a medical campus) a significant number of medical students in their senior years as well as staff have direct dealings with, and exposure to patients in the adjacent teaching hospital as part of their studies and routine duties. These, therefore, were considered as part of the frontline healthcare workers that were prioritized for the receipt of the COVID 19 vaccines, the roll-out of which at the time of the design of our study, was imminent. One of the main aims of our study was to investigate the intention to receive a COVID 19 vaccine when one becomes available. This cogent reason makes the population described above ideal for our study.
    Moreover, the selected study population is relevant to gaining some insight on the probable vaccine sentiments of future healthcare workers, identifying any issues of concern and planning how to mitigate them, and gauging how well they might likely advocate for vaccine acceptance. The representability of the current population views (though they are part of the larger population and possibly part...

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  • Due to selection bias, this study does not show a relationship between non-medical induction of labour at term and adverse outcomes

    I would like to congratulate Hannah Dahlen and colleagues on their recent publication in BMJ Open (1), particularly with respect to their follow-up of longer-term outcomes for infants born following induction of labour between 37 and 41 completed weeks gestational age compared with women who had a spontaneous onset of labour.
    Dahlen et al found that adverse maternal outcomes including caesarean section, instrumental birth, epidural use (potentially indicating a more painful and/or longer labour), episiotomy and post-partum haemorrhage were more common among women with an induced labour compared with women who went into spontaneous labour.
    They list absence of an intention-to-treat analysis as a weakness in the study design, but go on to say, “the data sources have a good track record of accuracy, so we do not believe these errors are likely to be large, or that they would have significantly influenced the direction of effect of the outcomes.”
    However, even if the data were perfectly accurate, the lack of intention-to-treat analysis causes a selection bias to an extent which makes it impossible to assess the impact of non-medically indicated induction of labour on maternal, neonatal, and child outcomes.
    In a randomised trial of planned induction of labour at a given gestational age, an intention-to-treat analysis will include all randomised women, including those who went on to have a later medically indicated induction of labour. Similarly, in an o...

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  • The PATCH-Trauma trial will add to the evidence for tranexamic acid in trauma

    We thank Prof. Roberts for his interest in the PATCH-Trauma trial. The PATCH-Trauma trial is by no means a criticism of the CRASH-2 trial.(1) Rather, it aims to evaluate the findings in a different setting. It remains paramount to externally validate results of trials whenever possible, regardless of how strong the effects may seem from a single trial.(2)

    We note some disagreement regarding the background material. However, these are largely subjective views and should not detract from the key objective of the manuscript that was to publish the protocol for improved interpretation of the study findings. For example, our definition of "high income countries" is different. Whether the CRASH-2 trial included 10% or 2% of its study population from high income countries does not change the fact that most participants were in low- and middle-income countries. Similarly, while the CRASH-2 investigators did publish a secondary analysis of their data, it could not address the mechanism of tranexamic acid’s potential effectiveness in critical bleeding.(3)

    We were encouraged that there were no critical comments regarding the methodology of the PATCH-Trauma trial or planned analysis. The PATCH-Trauma Trial has recruited 98.9% of its planned enrolment to date and we look forward to sharing the results of the study soon.

    1. Shakur H, Roberts I, Bautista R, et al. Effects of tranexamic acid on death, vascular occlusive events, and blood tr...

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  • A British Association of Cardiovascular Prevention and Rehabilitation (BACPR) response to the comment from the International Council of Cardiovascular Prevention and Rehabilitation (ICCPR)

    The BACPR would like to thank the ICCPR for their recent letter highlighting the work undertaken by both organisations. We are reassured to learn that the results of the ICCPR survey are similar to our own [1]. Both studies, conducted to support cardiovascular prevention and rehabilitation programmes, found that half of all cardiac rehabilitation services were cancelled during the first wave of COVID-19 (~March to June 2020). This is concerning because the closure of so many cardiac rehabilitation programmes is likely to have had a significant negative effect on patient outcomes, cause avoidable hospital admissions, and undermine government efforts to reduce the pressure on acute hospital and healthcare services, during the COVID-19 pandemic. We agree with the ICCPR that further work is needed to investigate whether cardiac rehabilitation services have been restored. The BACPR remain committed to undertaking research that guides decision making and would be happy to explore opportunities with the ICCPR to combine existing research datasets and conduct future collaborative projects.

    We believe that it is essential that government, governing bodies, and local policy makers, support cardiac rehabilitation teams to resume the delivery of effective services. Whilst restrictions on face-to-face human contact remain in place, services should be supported to adopt and refine remotely delivered models of cardiac rehabilitation. As we demonstrate in our survey [1], significan...

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  • Clarification

    Since the publication of the article, it has come to the authors’ attention that the flowchart (Figure 1) can be misleading. According to the flow chart, 1 738 358 pregnancies ending as an abortion were excluded due to missing gestational age or gestational age >140 days. This seems to be a large proportion of missing data, which could question the validity of the coding of abortions in the patient registry. It was, however, not at missing data problem but was due to technical reasons. In the raw data, a unique abortion could be recorded more than once. Removing duplicates is therefore a regular part of the data cleaning process when working with these data. In our data, 1 733 799 abortions were removed because they were duplicates, which would have been the correct designation in the flow chart rather than missing gestational age. Of notice, the final number of pregnancies included in the analyses was correct.

    Anne Staub Rasmussen
    Christian Fynbo Christiansen,
    Niels Uldbjerg,
    Mette Nørgaard

  • Comments regarding the data and conclusions reached.

    Dear Professor Dahlen et al

    Thank you for your research regarding this retrospective population linked data in NSW.

    We wish to make a number of comments regarding the methods and conclusions reached.

    Firstly, the premise of retrospectively comparing birth outcomes for induction versus spontaneous labour at a particular gestation is an erroneous one. It is not possible to elect to go into spontaneous labour. The only option available to women is elect to have an induction at a certain gestation, or to continue with the pregnancy, i.e. expectant management. Expectant management may include the pregnancy going post-dates, requiring an IOL at a later gestation, or the development of complications that are known to increase beyond 40 weeks including preeclampsia, placental insufficiency, stillbirth and macrosomia.

    It is for this simple reason that prospective RCT data that compares IOL at 39-40 weeks versus expectant management demonstrate a clear reduction in the rate of caesarean section, third and fourth degree perineal tears, and a reduction in perinatal adverse outcomes.

    It is not possible with your data to make any comment regarding the outcomes of IOL for no medical reason versus expectant management. Given, in reality, this is the only choice that women are able to make, we do not believe that your conclusion, that women may have an increased rate of caesarean section and adverse outcomes if they elect for an IOL, is supported at all...

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  • Incorrect data analyses by Atmore et al 2021.

    Atmore et al (2021) have reported findings from a general practice patient records review in New Zealand.1 Main research question was to compare harms between rural and urban locations. Sampling design was a stratified sampling design with unequal probabilities of selection from strata.2 Authors reported “weights developed from the SHARP study data were applied to enable generalisability of results to the NZ population”. Analyses include Chisquare test, Fishers exact test, independent sample t-test, Mann-Whitney test, Wald test, Poisson regression, and ordinal logistic regression. Some of these procedures cannot accommodate any type of weights, some can accommodate frequency weights but not sampling weights. So, with these procedures authors either may not have used sampling weights or may have incorrectly used them as frequency weights. Closer look at the presented results shows most, if not all, percentages reported are simply the simple percentages observed in data, ignoring sampling weights. In stratified sampling designs, researchers can observe any desired strata-specific percentage by altering the strata-specific sampling fraction of participants, therefore not using sampling weights or incorrectly using them to compare outcomes between strata almost always invalidate results. Further, authors have interpreted main effects from the regression models ignoring interaction effects. For these reasons, the results presented in the Atmore et al paper are unreliable, and t...

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  • Formal proof for an effect remains to be determined by randomized controlled trials

    The study authors acknowledge the delay from the point of submission of the article to final publication. This delay inevitably means that we were unable to offer a more current version but acknowledge that the field may have moved on as stated in implications of practice. We note that the value of systematic reviews is maximised when they are up-to-date and agree with the author that there may be new relevant evidence which has been published.

    We would like to thank the author for highlighting the issue of a much greater magnitude than the specific one related to our systematic review. Over the past two decades, several authors and organisations highlighted the tension between the average length of time for conducting a systematic review and long editorial process needed to publish the systematic review in a journal (median time: 15 months) versus the need for updating systematic reviews that arises due to emergence of new relevant evidence published over time (median time: 1-5 years).(1-5)

    We believe that the COVID-19 pandemic contributed towards even more prolonged duration of editorial process than usual by overburdening its staff with multiple submissions of studies on SARS-CoV-2 infection. Moreover, the topic of SARS-CoV-2 infection is a new and rapidly emerging field where the evidence for any given research question is still evolving, thus being insufficient and uncertain. In the context of the COVID-19 pandemic and the fast pace of published literat...

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