Cabbage? Open Science and cardiothoracic surgery

“The best thing about being a statistician is that you get to play in everyone’s backyard.” –a well-known quote from John Tukey.

Cabbage? That’s CABG–see below.

A week or so ago Lindy and I spent a very enjoyable 5 days of sun, surf, and sand at Noosa Heads in Queensland. I spoke at the Statistics Day of the Annual Scientific Meeting of ANZSCTS (Australian and New Zealand Society of Cardiothoracic Surgeons). The program is here (scroll down to p. 18).

My first talk, to open the day, was “Setting the scene–problems with current design, analysis and reporting of medical research”. The slides are here.

In the afternoon I spoke on “‘Open science’–the answer to the problem?”. The slides are here.

Once again, I learned that:

  • The problems of selective publication, lack of reproducibility, and lack of full access to data and materials are, largely, common across numerous disciplines. And many researchers have increasing awareness of such problems.
  • Familiar Open Science practices (preregistration, open materials and data, publishing whatever the results, …) have wide applicability. However, each discipline and research field needs to develop its own best strategies for achieving, as well as it can, Open Science goals.

Technology races on…

I referred to a 2018 meta-analysis (pic below) that combined the results of 7 RCTs that compared two ways to rejoin the two halves of the sternum (breast bone) after open-chest surgery. The conclusion was that there’s not much to choose between wires and traditional suturing.

That was a 2018 article, but two commercial exhibitors were touting the advantages of devices that they claimed were better than either procedure assessed in the Pinotti et al. review. One was a metal clamp that has, apparently, been used for thousands of patients in China and has just been approved for use in Australia, on the basis of one RCT. The second looked like up-market plastic cable ties.

Open Science may set out ideal practice for researchers, but meanwhile regulators and practitioners must constantly make judgments on the basis of possibly less than ideal amounts of evidence, less than desirable levels of precision of estimates.

PCI or CABG? Just run a replication!

PCI is percutaneous coronary intervention, usually the insertion of a stent in a diseased section of coronary artery. The stent is typically inserted via a major blood vessel, for example the femoral artery from the groin.

CABG (“Cabbage”) is the much more invasive coronary artery bypass grafting, which requires open-chest surgery.

How do they compare? Arie Pieter Kappetein told us the fascinating story of  research on that question. He described the SYNTAX study, a massive comparison of PCI and CABG that involved 85 centres across the U.S. and Europe. At the 5-year follow-up stage, little overall difference was found between the two very different techniques. Some clinical advice could be given. There were many valuable subgroup analyses, some of which gave only tentative conclusions.

Replication was needed! More than 5 years and $80M later, he could describe results from the even larger EXCEL study. Again, there were many valuable insights and little overall difference, and the researchers are now seeking funding to follow the patients beyond 5 years. Recently his team has published a patient-level meta-analysis of results from 11 randomised trials involving 11,518 patients. Some valuable differences were identified and recommendations for clinical practice were made but, again, there was little overall difference in several of the most important outcomes–such as death.

So, in some fields, replication, if possible at all, is rather more challenging than simply running another hundred or so participants on your simple cognitive task!


Some of the most interesting papers I attended were retrospective studies of cases sourced from large patient databases. Such databases, as large and detailed as possible, are a highly valuable research resource. One seminar was devoted to the practicalities of setting up a major thoracic database, alongside the existing Australian cardiac database. The vast range of practicalities to be considered made clear how challenging it is to set up and keep running such databases.

Co-incidentally, The New Yorker that week published a wonderful article by Atul Gawande–one of my favourite writers–with the title Why Doctors Hate Their Computers. It seemed to me so relevant to that day’s cardiothoracic database discussions.

I hope you never have to worry about whether to prefer PCI or cabbage!


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