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The WHI Hormone Replacement Data: Evidence to Implications
The Need for Evidence-based Medicine
Susan L. Hendrix, DO
Evidence-based medicine has been called “the conscientious,
explicit, and judicious use of current best evidence in making decisions
about the care of individual patients.”1
Individual clinical expertise, the best available evidence from
controlled clinical trials, and knowledge of patients’ values
and expectations are all vital elements of evidence-based medicine.
Physicians can improve patient care by habitually combining these
components in weighing treatment options.
ACCESSING KNOWLEDGE
The current shift to evidence-based medicine reflects the ongoing
developments taking place in clinical research, methodology, and
education, as well as the constant need to improve the practice
of medicine. At the same time, the virtual explosion that has occurred
in the amount of medical literature, frequency of study reports
and updates, and availability of scientific databases has enabled
health professionals to locate a large amount of research data.
For this reason, it is now more important than ever for the quality
of trials to be high, for clinicians to constantly seek this high-quality
evidence to support treatment protocols, and to act accordingly
when reliable data refute the usefulness of an intervention.
DETERMINING QUALITY
“Hierarchies of evidence” have been identified by
a number of educators to describe the significance with which different
types of study results should be weighed (Figure). Although exhibiting
slight variations, they all share the same top tier: the randomized
controlled trial, with an analysis focused on estimating the size
of the difference in predefined outcomes among treatment groups.
FIGURE. The Hierarchy of Evidence2
- N of 1 randomized trial
- Systematic reviews of randomized trials
- Single randomized trial
- Systematic review of observational studies addressing
patient-important outcomes
- Single observation study addressing patient-important
outcomes
- Physiologic studies
- Unsystematic clinical observations and expert opinion
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A CONTINUAL QUEST
The effective adoption of evidence-based medicine is dependent
on continuity. Patients require clinicians’ continual efforts
to seek the most rigorous study designs and unbiased outcomes as
evidence for health care decisions—even at the risk of destabilizing
popular therapies. The Women’s Health Initiative provides
an illustration of how the results of a high-quality trial can change
the status quo, and teaches a valuable lesson to practitioners:
Never stop questioning.
Susan L. Hendrix, DO, is associate professor of obstetrics
and gynecology, Division of Gynecology, and principal investigator,
Women’s Health Initiative, Wayne State University, Detroit,
Mich.
References
- Sackett DL, Rosenberg WM, Gray JA, et al. Evidence-based medicine:
what it is and what it isn't. BMJ. 1996;312(7023):71-72.
- Health Services Administration. Clinical epidemiology and evidence-based
medicine, aka: making the best clinical decision. Session 1: January
14, 2002, 1300-1350. Available at: http://hsa.usuhs.mil/2002ms2/trump/intronotsyllabus.htm.
Accessed September 11, 2002.
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