Randomized Controlled Trials: Questions, Answers, and Musings

Abstract

Alejandro R. Jadad and Murray W. EnkinSecond EditionBlackwell BMJ Books, Oxford, 2007$29.95,160 pp, pb The first edition of Alejandro Jadad’s Randomized Controlled Trials was published almost a decade ago, but it is still one of the most useful, important, relevant, thoughtful, and thought-provoking books about medical research. I must add that I have also mislaid several copies by lending the book to other people, who were not able to manage without their own reassuring—but challenging—copy. In the beginning I had been unsure about the benefits of the question-and-answer approach, but it did not take long before I came to see that the style, and selection of the content, contributed to long-term understanding and retention of crucial messages. The focus in the first edition was the supreme importance of randomization in implementing controlled trials. This new second edition, co-authored with Murray Enkin, has a slightly different focus with the subtitle of “Questions, Answers, and Musings.” This change might not seem very important, but as you read the book, the shift of emphasis seems to be substantial. The second edition includes a darker concern about sources of bias within randomized controlled trials, which is demonstrated even by the subheadings. The authors start with selection bias and ascertainment bias. They then draw the reader’s attention to the importance of the choice of a population, and the nature of the intervention(s) and the biases that can occur when there is selective inclusion or exclusion of data. The adverse impact of withdrawals, and dropouts in the quality of a trial is made very clear, as are protocol violations, and the need for thorough reporting. It was very good to see the chapter about the basis of evidence-based health care and the role of ethics in randomized trials—aspects that are not often addressed. The readers of this new book may feel a little confused or tired or worried about aspects of clinical trials, but they are sure to find a great deal of help and support at the same time. Congratulations—as always—to Alejandro Jadad and the unstoppable Murray Enkin.