trials are prospective cohort studies which often have some special wrinkles added
that cannot be used in ordinary cohort research. With one exception, the
following features are used in many clinical trials but are unavailable in
usual cohort research. Which is the exception?
c. placebo control
d. blinding the subject
e. blinding the treating clinician
2. Patients in
the control groups of randomized clinical trials seem to follow a better
clinical course than their counterparts not involved in research. With one
exception, the following choices may contribute to this phenomenon. Which is
a. placebo effect
b. selection criteria for clinical trials may screen out the sickest patients
c. more knowledgeable clinicians
d. protocol-directed, monitored therapy
e. intention-to-treat analysis
3. In an
"outcomes" analysis of coronary bypass surgery, health services
researchers identify charts of all patients diagnosed with three vessel disease
at three major clinical centers during the past ten years. These patients are
separated into those who initially were treated surgically and those who were
initially treated medically, with surgery used if medical treatment was
unsuccessful. Aggregate results for mortality and a variety of other outcome
variables were compiled for each group, to produce prognostic profiles for
those initially treated medically vs. those who received immediate surgery.
This study was a
a. prospective cohort study
b. retrospective cohort study
c. cross-sectional survey
d. hospital-based case-control study
e. controlled clinical trial
4. In the term "controlled clinical trial," the word "control" refers primarily to the inclusion of a comparison group which does not receive the experimental therapy. However, there are many other factors which may be controlled in such a study. Describe various other ways in which a clinical trial may be "controlled."
5. In a randomized clinical trial, the comparison between experimental and standard therapy fails to reveal any statistically significant difference. However, in exploring the data investigators discover a clinically distinguishable subgroup of patients in which the experimental therapy appears to have been superior. Describe clearly two major reasons why such a finding can rarely be regarded as definitive, even if apparently statistically significant.