Vaccine Efficacy in RCTs: Measures and Interpretation

In a study examining the effectiveness of a new vaccine, what is the most appropriate measure of association to use, given the study design is a randomized controlled trial (RCT)?

In an RCT evaluating a vaccine's efficacy against COVID-19, the incidence of COVID-19 in the vaccinated group is 8 out of 21,769, while in the placebo group, it is 162 out of 21,769. What is the calculated Relative Risk (RR)?

Based on a Relative Risk (RR) of 0.049 for a COVID-19 vaccine, how would you interpret the vaccine's effectiveness?

If a study initially includes 43,538 participants equally randomized into a vaccine group and a placebo group, and the results show a significant reduction in disease incidence in the vaccine group, what is the primary reason for using such a large sample size?

In the context of the presented study results, what is the most appropriate next step after calculating the relative risk and interpreting the vaccine's effectiveness?

If a study finds that a certain medication reduces the risk of a disease, yielding a Relative Risk (RR) of 0.4, what is the percentage decrease in risk associated with taking this medication?

Which study design involves random allocation of participants to different treatment groups?

A study investigating the effect of a new diet on heart disease risk reports a Relative Risk (RR) of 1.75. How should this be interpreted?

In a vaccine efficacy trial, the incidence of disease in the vaccinated group is 2% and in the placebo group is 8%. What is the Relative Risk (RR) of contracting the disease in the vaccinated group compared to the placebo group?

What is the primary distinction between efficacy and effectiveness in experimental studies?

A study examines the association between smoking and lung cancer. If the Relative Risk (RR) is 1, how should this be interpreted?

In which phase of clinical trials is the primary focus on assessing safety and dosage in a small group of healthy volunteers?

What is the initial step when you want to find associations in clinical data?

Which of the following is a key characteristic of Randomized Controlled Trials (RCTs) that distinguishes them from other study designs?

A researcher aims to study the impact of a new drug on blood pressure in hypertensive patients. They randomly assign patients to either the new drug or a placebo and monitor their blood pressure for 6 months. What type of study design is this?

A pharmaceutical company has developed a new drug and wants to evaluate its effectiveness in a real-world setting. They conduct a large-scale study involving multiple clinics and a diverse patient population. What type of evaluation are they primarily conducting?

Which phase of clinical trials involves post-marketing surveillance to monitor the long-term effects of a drug after it has been approved and is available for widespread use?

In an RCT evaluating a new exercise program for elderly adults, participants are randomly assigned to either the exercise group or a control group that receives standard care. What is the primary purpose of this randomization?

In the context of the provided COVID-19 vaccine trial data, what does a relative risk (RR) of 0.0555 indicate?

Given the provided data from the COVID-19 vaccine RCT, which conclusion is most accurate regarding the vaccine's effectiveness?

What does an inverse association, as determined from the relative risk, suggest in the context of a vaccine trial?

In the context of the study design, what is the primary advantage of using an RCT to evaluate a vaccine's effectiveness?

What is a major limitation of relying solely on RCTs to inform healthcare decisions?

Suppose a new vaccine trial for disease X yields a relative risk of 2.0. How would you interpret this result?

A pharmaceutical company is deciding whether to fund an RCT for a new drug. Which of the following factors would most likely be a significant disadvantage they need to consider?

If an RCT evaluating a new therapy shows statistically significant benefits but is deemed unethical, what is the most appropriate course of action?

In a study, the risk of a disease in an exposed group is 5% and the risk in an unexposed group is 2%. What is the relative risk?

In a study comparing a new treatment to a standard treatment, the risk of an adverse outcome in the new treatment group is 10%, while the risk in the standard treatment group is 15%. What is the risk difference?

If the relative risk of developing a certain disease for smokers compared to non-smokers is 4, how should this be interpreted?

In a clinical trial evaluating a new drug, the risk of a side effect is 5% in the treatment group and 1% in the placebo group. What is the absolute risk increase associated with the new drug?

A study finds that a new diet reduces the risk of heart disease by 30% relative to the standard diet. If the baseline risk of heart disease in the standard diet group is 10%, what is the risk in the new diet group?

Researchers are evaluating the effectiveness of a vaccine. In the unvaccinated group, the risk of infection is 8%. If the vaccine has a relative risk reduction of 50%, what is the risk of infection in the vaccinated group?

In a study comparing two different surgical techniques, the risk of complications with technique A is 6% and with technique B is 4%. Calculate the relative risk of complications when using technique A compared to technique B.

A public health campaign aims to reduce the incidence of a disease. Before the campaign, the incidence was 5 per 1,000 people. After the campaign, it is 3 per 1,000 people. What is the absolute risk reduction due to the campaign?

In a clinical trial assessing a new pain medication after surgery, what would be considered a primary endpoint?

Which of the following best describes a surrogate endpoint?

In the experimental study flow, what is the purpose of randomization?

What is the key difference between intention-to-treat (ITT) and per-protocol (PP) analysis?

A researcher is conducting a clinical trial on a new drug to improve patient outcomes after cardiac surgery. Which of the following would be a relevant secondary endpoint to measure?

In a study evaluating a new rehabilitation program for stroke patients, the primary endpoint is the improvement in motor function assessed using a standardized scale. Which of the following scenarios would be most appropriately analyzed using an intention-to-treat (ITT) approach?

A clinical trial is designed to evaluate the effectiveness of a new drug in reducing the recurrence of migraines. The researchers plan to measure the number of migraine-free days per month as the primary endpoint. What is a potential limitation of using this endpoint?

A research team is conducting a randomized controlled trial (RCT) to investigate the effectiveness of a new exercise program on improving cardiovascular health. After randomization, some participants in the intervention group stopped participating due to personal reasons, and some participants in the control group started exercising independently outside of the study. How does the per-protocol (PP) analysis address this?

Calculate % increase in risk (RR > 1)

Calculate % decrease in risk (RR < 1)

What is a 2x2 table?

Measure of association

1:1 ratio

Experimental Studies

Randomized Controlled Trial (RCT)

Efficacy

Effectiveness

Phase I Clinical Trials

Phase II Clinical Trials

Phase III Clinical Trials

Phase IV Clinical Trials

Primary Endpoint

Secondary Endpoint

Surrogate Endpoint

Randomization

Control Group

Follow-up

Intention-to-Treat Analysis

Per-Protocol Analysis

RCT (Randomized Controlled Trial)

Relative Risk (RR)

Inverse association

Percent Decrease (% decrease)

RCT Disadvantage: Expense and Time

RCT Disadvantage: Limited Scope

RCT Disadvantage: Ethical concerns

What is a 2x2 contingency table?

What does relative risk (RR) < 1 indicate?

How is Relative Risk (RR) calculated?

What does '% decrease' represent in this context?

What is the placebo group?

Absolute Risk Difference

Relative Risk Formula

Risk Difference Formula

Interpreting RR = 0.5

Interpreting Risk Difference = -0.02

Comparing RR and Risk Difference

Purpose of a 2x2 Table