A couple of weeks ago I announced that my team was looking for a new post-doc. I received many applications, some even from as far as Italy and Spain. Out of this pile of candidates we were able to find an individual candidate who fulfilled all the requirements we had mind and than some. It is great that she will join the team in December. JH has worked in the field of epidemiology for quite some time and is not only experienced in setting up new projects and provide physicians with methodological input on their clinical research projects, but she also has a great interest in the more methodological side of epidemiology. For example, she is co-author/developer of the program DAGitty which can be used to draw causal diagrams. She is also speaker for the working group methodology of the German Society of Epidemiology (dgEpi). Her background in psychology also means that she brings a lot of knowledge on methods that we as a team do not have so far. In short, a great addition to the team. Welcome JH!
A small group of epi-nerds (JLR, TK and myself) decided to start a colloquium on epidemiological methods. This colloquium series kicks off with a webcast of an event organised by the Society for Epidemiological Research (SER), but in general we will organize meetings focussed on advanced topics in epidemiological methods. Anyone interested is welcome. Regularly meetings will start in February 2017. All meetings will be held in English.
More information on the first event can be found below or via this link:
“Perspective of relative versus absolute effect measures” via SERdigital
Join us for a live, interactive viewing party of a debate between two leading epidemiologists, Dr. Charlie Poole and Dr. Donna Spiegelman, about the merits of relative versus absolute effect measures. Which measure of effect should epidemiologists prioritize? This digital event organized by the Society for Epidemiologic Research will also include three live oral presentations selected from submitted abstracts. There will be open discussion with other viewers from across the globe and opportunities to submit questions to the speakers. And since no movie night is complete without popcorn, we will provide that, too! For more information, see: https://epiresearch.org/ser50/serdigital
I was going to write a whole story on how one should not use a personal blog to continue the scientific debate. As you can guess, I ended up writing a full paragraph where I did this anyway. So I deleted that paragraph and I am going to do a thing that requires some action from you. I am just going to leave you with the links to the letters and let you decide whether the issues we bring up, but also the corresponding rebuttal of the authors, help to interpret the results from the the original publication.
Last week was the first edition of the European Congress on Thrombosis and Hemostasis in the Hague (NL). The idea of this conference is to provide a platform for european thrombosis researchers and doctors to meet in the dull years between ISTH meetings. There is a strong emphasis on enabling and training the young researchers, as can be from the different activities and organisational aspects. One os these things was the Junior advisory board, of which I was part. We had the task to give advice both solicited and unsolicited, and help organise and shape some of the innovative aspects. For example: we had the so-called fast and furious sessions, where authors of the best abstract were asked to let go of the standard presentation format and share their research TED talk style.
I learned a lot during these sessions, and even got in contact with some groups that have interesting methods and approaches that we might apply in our studies and patient populations. My thoughts: targeting FXII and FXI as well as DNAse treatment are the next big thing. We also had a great selection of speakers for meet-the-experts and how-to sessions. These sessions demanded active participation of all participants which is really a great way to build new collaborations and friendships.
The wednesday plenary sessions, including the talks on novel and innovative methods of scholarly communications as well as the very well received sessions from Malcolm Macloud on reducing research waste where inspiring to all. Missed it? do not worry, they have shared their slides online!
All in all, the conference was a great success in both numbers (750+ participants) as well as scientific quality. I am looking forward to the next edition, which will be held in Marseille in two years time. Hope to see you all there!
Good question, and even though thromboprofylaxis is already given according to guidelines in some countries, I can see the added value of a good discriminating prediction rule. Especially finding those patients with low DVT risk might be useful. But using d-dimer is a whole other question. To answer this, a thorough prediction model needs to be set up both with and without the information of d-dimer and only a direct comparison of these two models will provide the information we need.
In our view, that is not what the paper by Balogun et al did. And after critical appraisal of the tables and text, we found some inconsistencies that prohibits the reader from understanding what exactly was done and which results were obtained. In the end, we decided to write a letter to the editor, especially to prevent that other readers to mistakenly take over the conclusion of the authors. This conclusion, being that “D-dimer concentration with in 48 h of acute stroke is independently associated with development of DVT.This observation would require confirmation in a large study.” Our opinion is that the data from this study needs to be analysed properly to justify such an conclusion. One of the key elements in our letter is that the authors never compare the AUC of the model with and without d-dimer. This is needed as that would provide the bulk of the answer whether or not d-dimer should be measured. The only clue we have are the ORs of d-dimer, which range between 3-4, which is not really impressive when it comes to diagnosis and prediction. For more information on this, please check this paper on the misuse of the OR as a measure of interest for diagnosis/prediction by Pepe et al.
A final thing I want to mention is that our letter was the result of a mini-internship of one of the students at the Master programme of the CSB and was drafted in collaboration with our Virchow scholar HGdH from the Netherlands. Great team work!
Easter brought another publication, this time with the title
“Statins and risk of poststroke hemorrhagic complications”
I am very pleased with this paper as it demonstrates two important aspects of my job. First, I was able to share my thought on comparing current users vs never users. As has been argued before (e.g. by the group of Hérnan) and also articulated in a letter to the editor I wrote with colleagues from Leiden, such a comparison brings forth an inherent survival bias: you are comparing never users (i.e. those without indication) vs current users (those who have the indication, can handle the side-effects of the medication, and stay alive long enough to be enrolled into the study as users). This matter is of course only relevant if you want to test the effect of statins, not if you are interested in the mere predictive value of being a statin user.
The second thing about this paper is the way we were able to use data from the VISTA collaboration, which is a large amount of data pooled from previous stroke studies (RCT and observational). I believe such ways of sharing data brings forward science. Should all data be shared online for all to use? I do am not sure of that, but the easy access model of the VISTA collaboration (which includes data maintenance and harmonization etc) is certainly appealing.
Finally, it is here. The article I wrote together with WdH, MZ and RM was published in the European Journal of Risk and Regulation last week. And boy, did it take time! This whole project, an interdisciplinary project where epidemiological thinking was applied to questions of causal inference in tort law, took > 3 years – with only a couple of months writing… the rest was waiting and waiting and waiting and some peer review. but more on this later.
First some content. in the article we discuss the idea of proportional liability that adheres to the epidemiological concept of multi-causality. But the article is more: as this is a journal for non epidemiologist, we also provide a short and condensed overview of study design, bias and other epidemiological concepts such as counterfactual thinking. You might have recognised the theme from my visits to the Leiden Law school for some workshops. The EJRR editorial describes it asas: “(…) discuss the problem of causal inference in law, by providing an epidemiological viewpoint. More specifically, by scrutinizing the concept of the so-called “proportional liability”, which embraces the epidemiological notion of multi-causality, they demonstrate how the former can be made more proportional to a defendant’s relative contribution in the known causal mechanism underlying a particular damage.”
Getting this thing published was tough: the quality of the peer review was low (dare I say zero?),communication was difficult, submission system flawed etc. But most of all the editorial office was slow – first submission was June 2013! This could be a non-medical journal thing, i do not know, but still almost three years. And this all for an invited article that was planned to be part of a special edition on the link between epi and law, which never came. Due several delays (surprise!) of the other articles for this edition, it was decided that our article is not waiting for this special edition anymore. Therefore, our cool little insight into epidemiology now seems to be lost between all those legal and risk regulation articles. A shame if you ask me, but I am glad that we are not waiting any longer!
Although i do love interdisciplinary projects, and I think the result is a nice one, I do not want to go through this process again. No more EJRR for me.
Ow, one more thing… the article is behind a pay wall and i do not have access through my university, nor did the editorial office provide me with a link to a pdf of the final version. So, to be honest, I don’t have the final article myself! Feels weird. I hope EJRR will provide me with a pdf quite soon. In the meantime, anybody with access to this article, please feel free to send me a copy!
We published a new article just in PLOS Biology today, with the title:
“Where Have All the Rodents Gone? The Effects of Attrition in Experimental Research on Cancer and Stroke”
This is a wonderful collaboration between three fields: stats, epi and lab researchers. Combined we took a look at what is called attrition in the preclinical labs, that is the loss of data in animal experiments. This could be because the animal died before the needed data could be obtained, or just because a measurement failed. This loss of data can be translated to the concept of loss to follow-up in epidemiological cohort studies, and from this field we know that this could lead to substantial loss of statistical power and perhaps even bias.
But it was unknown to what extent this also was a problem in preclinical research, so we did two things. We looked at how often papers indicated there was attrition (with an alarming number of papers that did not provide the data for us to establish whether there was attrition), and we did some simulation what happens if there is attrition in various scenarios. The results paint a clear picture: the loss of power but also the bias is substantial. The degree of these is of course dependent on the scenario of attrition, but the message of the paper is clear: we should be aware of the problems that come with attrition and that reporting on attrition is the first step in minimising this problem.
A nice thing about this paper is that coincides with the start of a new research section in the PLOS galaxy, being “meta-research”, a collection of papers that all focus on how science works, behaves, and can or even should be improved. I can only welcome this, as more projects on this topic are in our pipeline!
My first conference experience (ISTH 2008, Boston) got me hooked on science. All these people doing the same thing, speaking the same language, and looking to show and share their knowledge. This is true when you are involved in the organisation. Organising the international soccer match at the Olympic stadium in Amsterdam linked to the ISTH 2013 to celebrate the 25th anniversary of the NVTH was fun. But lets not forget the exciting challenge of organising the WEON 2014.
And now, the birth of a new conference, the European Congress of Thrombosis and Hemostasis, which will be held in The Hague in Netherlands (28-30 sept 2016). I am very excited for several reasons: First of all, this conference will fill in the gap of the bi-annual ISTH conferences. Second, I have the honor to help out as the chair of the junior advisory board. Third, the Hague! My old home town!
So, we have 10 months to organise some interesting meetings and activities, primary focussed on the young researchers. Time to get started!