Between the Lines. Finding the Truth in Medical Literature [Book Review]

19 07 2013

In the 1970s a study was conducted among 60 physicians and physicians-in-training. They had to solve a simple problem:

“If a test to detect a disease whose prevalence is 1/1000 has a false positive rate of 5 %, what is the chance that a person found to have a positive result actually has the disease, assuming that you know nothing about the person’s symptoms or signs?” 

Half of the “medical experts” thought the answer was 95%.
Only a small proportion, 18%, of the doctors arrived at the right answer of 2%.

If you are a medical expert who comes the same faulty conclusion -or need a refresher how to arrive at the right answer- you might benefit from the book written by Marya Zilberberg: “Between the Lines. Finding the Truth in Medical Literature”.

The same is true for a patient whose doctor thinks he/she is among the 95% to benefit form such a test…
Or for journalists who translate medical news to the public…
Or for peer reviewers or editors who have to assess biomedical papers…

In other words, this book is useful for everyone who wants to be able to read “between the lines”. For everyone who needs to examine medical literature critically from time to time and doesn’t want to rely solely on the interpretation of others.

I hope that I didn’t scare you off with the abovementioned example. Between the Lines surely is NOT a complicated epidemiology textbook, nor a dull studybook where you have to struggle through a lot of definitions, difficult tables and statistic formulas and where each chapter is followed by a set of review questions that test what you learned.

This example is presented half way the book, at the end of Part I. By then you have enough tools to solve the question yourself. But even if you don’t feel like doing the exact calculation at that moment, you have a solid basis to understand the bottomline: the (enormous) 93% gap (95% vs 2% of the people with a positive test are considered truly positive) serves as the pool for overdiagnosis and overtreatment.

In the previous chapters of Part I (“Context”), you have learned about the scientific methods in clinical research, uncertainty as the only certain feature of science, the importance of denominators, outcomes that matter and outcomes that don’t, Bayesian probability, evidence hierarchies, heterogeneous treatment effects (does the evidence apply to this particular patient?) and all kinds of biases.

Most reviewers prefer part I of the book. Personally I find part II (“Evaluation”) as interesting.

Part II deals with the study question, and study design, pros and cons of observational and interventional studies, validity, hypothesis testing and statistics.

Perhaps part II  is somewhat less narrative. Furthermore, it deals with tougher topics like statistics. But I find it very valuable for being able to critically appraise a study. I have never seen a better description of “ODDs”: somehow ODDs it is better to grasp if you substitute “treatment A” and “treatment B” for “horse A” and “horse B”, and substitute “death” for “loss of a race”.
I knew the basic differences between cohort studies, case control studies and so on, but I kind of never realized before that ODDs Ratio is the only measure of association available in a case-control study and that case control studies cannot estimate incidence or prevalence (as shown in a nice overview in table 4).

Unlike many other books about “the art of reading of medical articles”, “study designs” or “Evidence Based Medicine”, Marya’s book is easy to read. It is written at a conversational tone and statements are illustrated by means of current, appealing examples, like the overestimation of risk of death from the H1N1 virus, breast cancer screening and hormone replacement therapy.

Although I had printed this book in a wrong order (page 136 next to 13 etc), I was able to read (and understand) 1/3 of the book (the more difficult part II) during a 2 hour car trip….

Because this book is comprehensive, yet accessible, I recommend it highly to everyone, including fellow librarians.

Marya even mentions medical librarians as a separate target audience:

Medical librarians may find this book particularly helpful: Being at the forefront of evidence dissemination, they can lead the charge of separating credible science from rubbish.

(thanks Marya!)

In addition, this book may be indirectly useful to librarians as it may help to choose appropriate methodological filters and search terms for certain EBM-questions. In case of etiology questions words like “cohort”, “case-control”, “odds”, “risk” and “regression” might help to find the “right” studies.

By the way Marya Ziberberg @murzee at Twitter and she writes at her blog Healthcare etc.

p.s. 1 I want to apologize to Marya for writing this review more than a year after the book was published. For personal reasons I found little time to read and blog. Luckily the book lost none of its topicality.

p.s. 2 patients who are not very familiar with critical reading of medical papers might benefit from reading “your medical mind” first [1]. 

bwtn the lines

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2 responses

29 07 2013
Who are you addicted to on Twitter? Research watchdog edition. | Susannah Fox

[…] post often, but each one is a gem. Don’t take my word for it: read Laika’s review of Marya’s book, Between the Lines. Finding the Truth in Medical […]

9 09 2013
THE excitement index tm | crossed wires

[…] Between the Lines. Finding the Truth in Medical Literature [Book Review] (laikaspoetnik.wordpress.com) […]

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