PBH 452: Chapters 10 & 11 - Randomized Controlled Trials

Vocabulary flashcards covering randomized controlled trials (RCTs), trial designs, clinical trial phases, biases, blinding, and foundational epidemiology concepts from Chapters 10 and 11.

Randomized Control Trial (RCT)

A study design considered the gold standard for analytical studies in which participants are randomly allocated to either a control or test group entirely by chance to evaluate the safety and effectiveness of medical treatments, community interventions, or health education programs.

Randomization

The process of allocating study participants to groups entirely by chance (such as through computer generation), giving every participant a fair chance of selection and evenly distributing both known and unknown variables.

Parallel RCT (Simple RCT)

A trial design where patients are randomly assigned to either a treatment group or a control group and remain within those designated groups throughout the intervention, follow-up, and outcome comparison phases.

Crossover RCT

A study design in which groups receive an initial intervention or control, undergo a washout period, and then switch assignments so each participant serves as their own comparison across different phases.

Washout period

A required time interval between intervention phases in a crossover trial designed to prevent residual side effects or health changes from carrying over into the next group phase.

Phase 1 Clinical Trial

The clinical trial phase conducted in $20\text{--}80$ participants after preclinical testing once a drug is approved for testing in humans.

Phase 2 Clinical Trial

The clinical trial phase conducted in $100\text{--}300$ participants to evaluate the preliminary safety and effectiveness of a drug.

Phase 3 Clinical Trial

A large-scale clinical trial phase conducted in $1{,}000\text{--}3{,}000$ participants to confirm safety and effectiveness before submitting the drug for FDA approval.

Phase 4 Clinical Trial

The post-marketing clinical trial phase conducted in $1{,}000+$ participants after a drug receives FDA approval to monitor long-term safety and outcomes.

Selection bias

A systematic error resulting from how study subjects are recruited or lost during follow-up, preventing the study's findings from being generalized to a broader, more diverse population.

Information bias

A systematic error arising from inaccuracies in data collected regarding exposure or health status, which can lead to erroneous conclusions about an intervention's efficacy or safety.

Confounding bias

A bias that occurs when a third variable has an indirect effect on both the exposure variable and the health outcome variable.

Single-blinded study

A trial design in which the participant is unaware of whether they have been assigned to the treatment group or the control group.

Double-blinded study

A trial design in which neither the participant nor the researcher knows which group the participant has been assigned to.

Triple-blinded study

A trial design in which participants, data analysts, and researchers are all unaware of group allocations.

Placebo effect

The phenomenon where a participant experiences perceived or actual improvement in their condition driven by their belief in a treatment after receiving an inactive or inert substance.

Nocebo effect

The phenomenon where a participant expects an intervention to cause negative consequences and consequently develops adverse symptoms despite receiving an inactive or inert substance.

Analytical studies

Epidemiologic study designs formulated specifically to answer the two core questions: 'Why?' and 'How?'.

Retrospective cohort study

An observational study design that uses past information to identify individuals based on exposure status and examines how those exposures relate to current health outcomes.

Recall bias

A form of information bias that occurs when a participant cannot accurately remember when or if they were exposed to a past variable of interest.

Temporality

The criterion of causality demonstrating that an exposure variable occurred prior in time to the development of a health outcome variable.