This final chapter has several purposes. Most importantly, it
ties together concepts and skills presented in previous chapters
and applies these concepts very specifically to reading medical
journal articles. Throughout the text, we have attempted to illustrate
the strengths and weaknesses of some of the studies discussed, but
this chapter focuses specifically on those attributes of a study that
indicate whether we, as readers of the medical literature, can use
the results with confidence. The chapter begins with a brief summary
of major types of medical studies. Next, we examine the anatomy
of a typical journal article in detail, and we discuss the contents
of each component—abstract or summary, introduction, methods,
results, discussion, and conclusions. In this examination, we also
point out common shortcomings, sources of bias, and threats to the
validity of studies.
Clinicians read the literature for many different reasons. Some
articles are of interest because you want only to be aware of advances
in a field. In these instances, you may decide to skim the article with
little interest in how the study was designed and carried out. In
such cases, it may be possible to depend on experts in the field
who write review articles to provide a relatively superficial level of
information. On other occasions, however, you want to know whether
the conclusions of the study are valid, perhaps so that they can
be used to determine patient care or to plan a research project.
In these situations, you need to read and evaluate the article with
a critical eye in order to detect poorly done studies that arrive
at unwarranted conclusions.
To assist readers in their critical reviews, we present a checklist
for evaluating the validity of a journal article. The checklist
notes some of the characteristics of a well-designed and well-written article.
The checklist is based on our experiences with medical students,
house staff, journal clubs, and interactions with physician colleagues.
It also reflects the opinions expressed in an article describing
how journal editors and statisticians can interact to improve the
quality of published medical research (Marks et al, 1988). A number
of authors have found that only a minority of published studies
meet the criteria for scientific adequacy. The checklist should
assist you in using your time most effectively by allowing you to
differentiate valid articles from poorly done studies so that you
can concentrate on the more productive ones.
Two guidelines recently published increase our optimism that
the quality of the published literature will continue to improve.
The International Conference on Harmonization (ICH) E9 guideline “Statistical
Principles for Clinical Trials” (1999) addresses issues
of statistical methodology in the design, conduct, analysis, and
evaluation of clinical trials. Application of the principles is intended
to facilitate the general acceptance of analyses and conclusions
drawn from clinical trials.
The International Committee of Medical Journal Editors published
the Uniform Requirements of Manuscripts Submitted to Biomedical