Responses

Download PDFPDF

Cannabis exposure as an interactive cardiovascular risk factor and accelerant of organismal ageing: a longitudinal study
Compose Response

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
Author Information
First or given name, e.g. 'Peter'.
Your last, or family, name, e.g. 'MacMoody'.
Your email address, e.g. higgs-boson@gmail.com
Your role and/or occupation, e.g. 'Orthopedic Surgeon'.
Your organization or institution (if applicable), e.g. 'Royal Free Hospital'.
Statement of Competing Interests

PLEASE NOTE:

  • A rapid response is a moderated but not peer reviewed online response to a published article in a BMJ journal; it will not receive a DOI and will not be indexed unless it is also republished as a Letter, Correspondence or as other content. Find out more about rapid responses.
  • We intend to post all responses which are approved by the Editor, within 14 days (BMJ Journals) or 24 hours (The BMJ), however timeframes cannot be guaranteed. Responses must comply with our requirements and should contribute substantially to the topic, but it is at our absolute discretion whether we publish a response, and we reserve the right to edit or remove responses before and after publication and also republish some or all in other BMJ publications, including third party local editions in other countries and languages
  • Our requirements are stated in our rapid response terms and conditions and must be read. These include ensuring that: i) you do not include any illustrative content including tables and graphs, ii) you do not include any information that includes specifics about any patients,iii) you do not include any original data, unless it has already been published in a peer reviewed journal and you have included a reference, iv) your response is lawful, not defamatory, original and accurate, v) you declare any competing interests, vi) you understand that your name and other personal details set out in our rapid response terms and conditions will be published with any responses we publish and vii) you understand that once a response is published, we may continue to publish your response and/or edit or remove it in the future.
  • By submitting this rapid response you are agreeing to our terms and conditions for rapid responses and understand that your personal data will be processed in accordance with those terms and our privacy notice.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

Vertical Tabs

Other responses

Jump to comment:

  • Published on:
    Response to Lane
    • Albert S. Reece, Professor University of Western Australia
    • Other Contributors:
      • Gary K. Hulse, Professor

    We wish to thank Dr Lane for his interest in our study. We are pleased to see statistical input to the issues of cannabis medicine as we feel that sophisticated statistical methodologies have much to offer this field.

    Most of the concerns raised are addressed in our very detailed report. As described our research question was whether, in our sizeable body of evidence (N=13,657 RAPWA studies), we could find evidence for the now well-described cannabis vasculopathy and what such implications might be. As this was the first study of its type to apply formal quantitative measures of vascular stiffness to these questions it was not clear at study outset if there would be any effect, much less an estimate of effect size. In the absence of this information power calculations would be mere guesswork. Nor indeed are they mandatory in an exploratory study of this type. Similarly the primary focus of our work was on whether cannabis exposure was an absolute cardiovascular risk factor in its own right, and how it compared to established risk factors. Hence Table 2 contains our main results. The role of Table 1 is to illustrate the bivariate (uncorrected) comparisons which can be made, show the various groups involved, and compare the matching of the groups. It is not intended to be a springboard for effect-size-power calculations which are of merely esoteric interest. Calculations detailing the observed effect size are clearly described in our text being 11.84% and 8....

    Show More
    Conflict of Interest:
    None declared.
  • Published on:
    Re: Cannabis exposure as an interactive cardiovascular risk factor and accelerant of organismal ageing: A longitudinal study
    • Ian A Lane, Clinical & Population Health Researcher University of Massachusetts Medical School

    I have read with interest Reece and colleagues (2016) paper, but some questions remain.

    First, I think the authors have done a commendable job detailing most of their statistical methodology. However, some things are left to be desired, such as a description of the Statistical Power analysis. Using the Benjamini-Hochberg Procedure (a modified Bonferroni Procedure) on the data listed in their Supplementary materials, one can conclude that the authors' results were indeed statistically significant. What remains to be seen, however, is what the magnitude of these effects were, precisely, and what happened to the Power as these multiple comparisons were assessed, since Power decreases with increasing univariate statistical tests. One might assume Power to be sufficient given the N = 1,553, but these data have been parsed in many different ways, and it would be helpful to know the authors’ anticipated effect sizes and any Power analyses for these comparisons that were conducted prior to the start of the study.

    Second, due to issues with boundary conditions and computational modeling, the method used in this paper for the mixed-effects linear model may not be quite right [1, 2]. There is often a misapplication of traditional AIC selection criteria in linear mixed effects (LME) modeling, owing to poor justification for use in longitudinal data analysis, due in part to error variance estimates [2], which is partially how this seemed to have been used here, in th...

    Show More
    Conflict of Interest:
    None declared.