Chapter·Behavioral ScienceStudy designs

Randomized controlled trialsDownloads

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1

A 21-year-old man presents to the office for a follow-up visit. He was recently diagnosed with type 1 diabetes mellitus after being hospitalized for diabetic ketoacidosis following a respiratory infection. He is here today to discuss treatment options available for his condition. The doctor mentions a recent study in which researchers have developed a new version of the insulin pump that appears efficacious in type 1 diabetics. They are currently comparing it to insulin injection therapy. This new pump is not yet available, but it looks very promising. At what stage of clinical trials is this current treatment most likely at?

APhase 0

BPhase 2

CPhase 3

DPhase 1

EPhase 4

2

A group of investigators seeks to compare the non-inferiority of a new angiotensin receptor blocker, salisartan, with losartan for reduction of blood pressure. 2,000 patients newly diagnosed with hypertension are recruited for the trial; the first 1,000 recruited patients are administered losartan, and the other half are administered salisartan. Patients with a baseline systolic blood pressure less than 100 mmHg are excluded from the study. Blood pressure is measured every week for four weeks, with the primary outcome being a reduction in systolic blood pressure by salisartan within 10% of that of the control. Secondary outcomes include incidence of subjective improvement in symptoms, improvement of ejection fraction, and incidence of cough. 500 patients withdraw from the study due to symptomatic side effects. In an intention-to-treat analysis, salisartan is deemed to be non-inferior to losartan for the primary outcome but inferior for all secondary outcomes. As the investigators launch a national advertising campaign for salisartan, independent groups report that the drug is inferior for its primary outcome compared to losartan and associated with respiratory failure among patients with pulmonary hypertension. How could this study have been improved?

AIncreased study duration

BPosthoc analysis of primary outcome among patients who withdrew from study

CRandomization

DIncreased sample size

ERetrial of primary outcome for clinical effectiveness instead of non-inferiority

3

A research team is studying the effects of a novel drug that was discovered to treat type 2 diabetes. In order to learn more about its effects, they follow patients who are currently taking the drug and determine whether there are adverse effects that exceed anticipated levels and may therefore be drug-related. They discover that the drug causes an excess of sudden cardiac death in 19 patients with renal failure out of 2 million total patients that are followed. Based on these results, an additional warning about this serious adverse effect is added to the investigator brochure for the drug. Which of the following clinical phase studies does this study most likely describe?

APhase IV

BPhase II

CPhase V

DPhase III

EPhase I

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