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In this blog interview José Manuel Ordóñez Mena shares with us which systematic review that he’s led or been involved in he would choose to take with him to read, if he was stranded on a desert island.

A beautiful island with white sands, palm trees, turquoise sea and deep blue sky with a pot of vitamin D pills superimposed

Can you introduce yourself and share your role in the MSc EBHC (Systematic Reviews) programme?
My name is José Manuel Ordóñez Mena, but everyone calls me Jose [Hoh-Seh]. I am a senior medical statistician working at the Clinical Informatics and Health Outcomes Research Group of the Nuffield Department of Primary Care Health Sciences. I am interested in the analysis of large epidemiological studies and routinely collected health care data, as well as in complex meta-analysis methods. I am one of the Meta-Analysis module coordinators.

If you were stranded on a "Desert Island", which systematic review that you have led or been involved in might you take with you to read?
It is a hard decision for me. It would either be my first systematic review ever, which I completed during my PhD and searched for observational studies on the association of serum vitamin D concentrations with all cancer incidence and mortality; or my first network meta-analysis that I did when I started in Oxford in January 2016, which extracted all trials from systematic reviews of drugs for treating giardiasis. I would probably take both.

What type of reviews were they?
The first one was a systematic review of epidemiological studies with meta-analysis and no critical appraisal, which at that time you could get away with publishing. Nowadays it would be more difficult for a journal to accept a systematic review without critical appraisal of studies.

 The second one was an overview of systematic reviews and literature search update. In brief, we identified all systematic reviews comparing drugs for treating giardiasis. We then extracted all trials from these reviews, and updated their literature search. This approach has actually been followed by a few students in their MSc in Medical Statistics dissertations. After collating all studies, we did critical appraisal of them, and then analyzed them using network meta-analysis.

Why did you choose these reviews?
The first one was my first ever systematic review and meta-analysis. My colleagues were using the Comprehensive Meta-Analysis software, but we only had a copy of that software in a laptop, and somebody else was using it, so I decided to write the mathematical formulate in Excel, as I did not know how to use Stata or R at that time.

For the second one I was mostly responsible for decisions on the methods. It was my first project in Oxford and allowed me to learn R, which I now use for every data analysis. I was also lucky enough to be able to present the findings of this project in the VI International Giardia and Cryptosporidium Conference, which took place that year in Havana, Cuba.

What did your reviews show?
The first review showed that higher blood concentrations of vitamin D were associated with lower cancer incidence and mortality. It is a finding that clinical trials still haven’t been able to reproduce.

The second one produced a ranking of the most effective and safe drugs for treating giardiasis. Unfortunately, the most effective drugs aren’t always licensed in the countries that need them most, like in Cuba. More recently, one of the drugs that we found to be most effective was introduced into the WHO Model List of Essential Medicines. Hopefully this can help for these effective drugs to be available worldwide.

What did you particularly enjoy about the reviews?
For the first it was learning about how to do a systematic review and meta-analysis.

For the second one it was about learning to program in R and learning about network meta-analysis methods. Thanks to that project I know teach the Network Meta-Analysis session on the Meta-Analysis module, which I can highly recommend to anybody who wants to embark in such a project.

Reflecting on your reviews, what one learning would you offer individuals completing a systematic review for the first time?
I had very little help on my first systematic review, and I had to learn a lot by myself, which was very time consuming and frustrating. I would recommend you all to make sure you get a good team to support you, particularly in the areas you struggle with more. For example, involve an experienced librarian to help you refine your search strategy, or a systematic reviewer to advise you on critical appraisal of studies, or a statistician to supervise your meta-analysis.

Finally, If you were stranded on a "Desert Island" and about to read your review, what one food or drink treat would you bring with you?
I remember when I was doing my PhD and worked on my first systematic review that I got myself a French press and started working on my coffee addiction. I would probably bring that cafetière with me and enjoy my coffee while remembering those good old times.


You can learn more about the MSc EBHC (Systematic Reviews) programme through the dedicated webpage or by contacting

The views expressed in this blog are those of the author and do not necessarily represent the views of CEBM as a group.