Randomized controlled trials: randomize, control, blind
Explains the three design features that let a randomized controlled trial (RCT) show a drug works — randomization, a placebo control and double-blinding — and the ways real trials fall short.
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- Primary effects and side effects — Trials are how side effects are separated from coincidence.
- The course lens: biopsychosocial, and no 'chemical imbalance' — The psychological part of the biopsychosocial lens is what placebo controls account for.
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- Expectancy: placebo and nocebo effects — Why expectancy is powerful enough to need a placebo group.
- Phases of drug trials: from animals to Phase IV — RCTs are the core of Phase III.
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Randomized controlled trials are “the ‘gold standard’ of clinical research”: randomized – random selection and assignment to groups, including double-blind; controlled – compare “drug” group with “control” group(s). For a drug to be considered effective, outcomes must improve BEYOND what is seen with sham. Why do we need to do this? Expectancy effects.
Términos del curso
Las palabras de tu profesor, tal cual aparecen en las diapositivas. Aprende el término y esta definición; la explicación de abajo solo ayuda a entenderla.
- Randomized controlled trial
“The “gold standard” of clinical research”Diapositivas 07, p. 2
Its experimental design allows claims about causality: the drug is causing the beneficial effect.
- Randomized
“Randomized – random selection and assignment to groups”Diapositivas 07, p. 3
Chance decides who gets the drug, so the groups start out alike.
- Double-blind
“participants and clinicians don’t know who is in what group”Diapositivas 07, p. 3
Blocks the expectations of both sides from tilting the results.
- Controlled
“Controlled – compare “drug” group with “control” group(s)”Diapositivas 07, p. 3
Arms can get the drug (possibly at different doses), nothing (pure control) or a sham such as a sugar pill.
- Placebo run-in
“every patient is administered a placebo for a week”Diapositivas 07, p. 10
Patients who respond positively are removed from the study — which raises the question of who is left.
- Open-label study
“In open-label studies, there is no blinding – participants (and clinicians) know that they are taking a drug or a placebo…openly!”Diapositivas 07, p. 11
Placebo effects still appear, through the conditioned ritual of taking a pill.
De tu curso: Course slides 07, pp. 2–3, 10–11, 17–22 · Midterm study guide: Clinical Trials and Policy
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