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A clinical trial is the direct comparison of two or more
treatment modalities in human groups.- Evidence-based medicine is the integration of current best
evidence with clinical expertise, pathophysiological knowledge,
and patient preferences to make health decisions.
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The practice of evidence-based medicine is encouraged because
it may lead to more consistent and objective clinical decisions.
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A type I error occurs when a study finds a difference in effectiveness
between the treatments being compared when in fact no difference
exists.
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A type II error occurs when a study fails to find a difference
in treatment effectiveness between the treatments being compared
when in fact a difference does exist.
- Statistical power is the ability of a study to detect a true
difference between groups being compared.
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When treatments are assigned by randomization, probability
alone determines assignment, rather than the personal preferences
of either physicians or patients.
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When patients are unaware of their treatment assignment in
a clinical trial, it is referred to as a single-blinded study. In
a double-blinded study, neither the patients nor the treating physicians know
individual treatment assignments.
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A ratio of either rates or risks can be used to compare the
outcomes in the experimental and control groups.
- Meta-analysis is a statistical integration of the results
of several independent studies.
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A sensitivity analysis can be used to determine whether differences
across studies may be explained by characteristics of the various
populations studied.
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An active 13-year-old middle school student complains to her
parents of increasing thirst, frequency of urination, and fatigue
that has persisted for a week. The following morning, the girl and her
parents visit their family pediatrician. While taking the history,
the physician notes the above-mentioned symptoms, as well as a decrease
in the girl’s academic performance over the previous week.
She is consuming more than 3 liters of liquid a day and urinating
approximately eight times during a 24-hour period; at least one
of those times requires her to awaken from sleep. On physical examination,
she is found to be afebrile, with a pulse of 80, which is slightly
elevated for the patient, a normal blood pressure lying and sitting,
and a normal respiratory rate. The pediatrician notes that the girl’s
weight has dropped 2 kg since a visit 3 months earlier. The remainder
of the physical examination is unremarkable.
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In the office, the pediatrician performs a urinalysis, which
reveals a normal microscopic examination; the dipstick examination
of the urine is negative for blood, white blood cells, and bilirubin, but
is 4+ positive for glucose and 1+ positive for
ketones. The pediatrician expresses concern to the parents that
the girl may have diabetes mellitus. A complete blood count and
blood chemistries are sent to a local laboratory, and the doctor
arranges for the patient and her parents to see a pediatric endocrinologist
within the hour.
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In the endocrinologist’s office, the results of the
blood tests confirm that the girl has a markedly ...