8 / 220
This 2017 Home Study Course Section does not include any discussion of drugs and devices that
have not been approved by the United States Food and Drug Administration.
Disclaimer
The information contained in this activity represents the views of those who created it and does
not necessarily represent the official view or recommendations of the American Academy of
Otolaryngology – Head and Neck Surgery Foundation.
March 13, 2017:
Suggested section 7 Exam submission deadline; course closed
August 4, 2017.
EVIDENCE BASED MEDICINE
The AAO-HNSF Education Advisory Committee approved the assignment of the appropriate level of
evidence to support each clinical and/or scientific journal reference used to authenticate a continuing
medical education activity. Noted at the end of each reference, the level of evidence is displayed in this
format:
[EBM Level 3]
.
Oxford Centre for Evidence-based Medicine Levels of Evidence (May 2001)
Level 1
Randomized
1
controlled trials
2
or a systematic review
3
(meta-analysis
4
) of randomized
controlled trials
5
.
Level 2
Prospective (cohort
6
or outcomes) study
7
with an internal control group or a systematic review
of prospective, controlled trials.
Level 3
Retrospective (case-control
8
) study
9
with an internal control group or a systematic review of
retrospective, controlled trials.
Level 4
Case series
10
without an internal control group (retrospective reviews; uncontrolled cohort or
outcome studies).
Level 5
Expert opinion without explicit critical appraisal, or recommendation based on
physiology/bench research.
Two
additional ratings
to be used for articles that do not fall into the above scale. Articles that are informational only
can be rated N/A , and articles that are a review of an article can be rated as Review. All definitions adapted from
Glossary of Terms, Evidence Based Emergency Medicine at New York Academy of Medicine a
t www.ebem.org .1
A technique which gives every patient an equal chance of being assigned to any particular arm of a controlled
clinical trial.
2
Any study which compares two groups by virtue of different therapies or exposures fulfills this definition.
3
A formal review of a focused clinical question based on a comprehensive search strategy and structure critical
appraisal.
4
A review of a focused clinical question following rigorous methodological criteria and employing statistical
techniques to combine data from independently performed studies on that question.
5
A controlled clinical trial in which the study groups are created through randomizations.
6
This design follows a group of patients, called a “cohort”, over time to determine general outcomes as well as
outcomes of different subgroups.
7
Any study done forward in time. This is particularly important in studies on therapy, prognosis or harm, where
retrospective studies make hidden biases very likely.
8
This might be considered a randomized controlled trial played backwards. People who get sick or have a bad
outcome are identified and “matched” with people who did better. Then, the effects of the therapy or harmful
exposure which might have been administered at the start of the trial are evaluated.
9
Any study in which the outcomes have already occurred before the study has begun.
10
This includes single case reports and published case series.