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  • image A clinical trial is the direct comparison of two or more treatment modalities in human groups.
  • imageEvidence-based medicine is the integration of current best evidence with clinical expertise, pathophysiological knowledge, and patient preferences to make health decisions.
  • image The practice of evidence-based medicine is encouraged because it may lead to more consistent and objective clinical decisions.
  • image A type I error occurs when a study finds a difference in effectiveness between the treatments being compared when in fact no difference exists.
  • image 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.
  • imageStatistical power is the ability of a study to detect a true difference between groups being compared.
  • image When treatments are assigned by randomization, probability alone determines assignment, rather than the personal preferences of either physicians or patients.
  • image 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.
  • image A ratio of either rates or risks can be used to compare the outcomes in the experimental and control groups.
  • imageMeta-analysis is a statistical integration of the results of several independent studies.
  • image A sensitivity analysis can be used to determine whether differences across studies may be explained by characteristics of the various populations studied.

image 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.

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.

In the endocrinologist’s office, the results of the blood tests confirm that the girl has a markedly ...

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