A study to assess spironolactone's efficacy in patients with heart failure is performed. 450 patients receive either spironolactone or placebo for two years. Neither the patients nor physicians are aware of who takes the drug or placebo. The study setup described above is most effective in preventing:

Question

A study to assess spironolactone's efficacy in patients with heart failure is performed.  450 patients receive either spironolactone or placebo for two years.  Neither the patients nor physicians are aware of who takes the drug or placebo.  The study setup described above is most effective in preventing:

Quizplus · Accepted Answer

Blinding technique is commonly used in clinical trials. The blinding can involve patients exclusively or both patients and physicians (double blinding). The main purpose of blinding is to prevent patient or researcher expectancy from interfering with the determination of an outcome. For example, a researcher's belief in a positive outcome in treated patients can potentially result in observer bias. (Choice A) Beta error refers to a conclusion that there is no difference between the groups studied when a difference truly exists. Beta error is a random error, not a systematic error (i.e., bias). (Choice B) Recall bias results from the inaccurate recall of past exposure by subjects. It applies mostly to case-control studies. (Choice D) Effect modification is not a bias and should not be controlled. (Choice E) Selection bias results from the manner in which people are selected for the study, or from the selective losses from follow-up. Educational Objective: The main purpose of blinding is to prevent patient or researcher expectancy from interfering with an outcome.

A Study to Assess Spironolactone's Efficacy in Patients with Heart