RCTs

RCTs US Medical PG Question 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?

• A. Phase 0
• B. Phase 2
• C. Phase 3 (Correct Answer)
• D. Phase 1
• E. Phase 4

RCTs Explanation: ***Phase 3*** - **Phase 3 trials** involve large-scale studies comparing the new treatment to standard therapy or placebo, often across multiple centers. - The scenario describes a "new version of the insulin pump" being compared to "insulin injection therapy," indicating a definitive comparison for efficacy and safety against existing treatments. *Phase 0* - **Phase 0 trials** are exploratory, small-scale studies (10-15 subjects) using micro-doses to gather preliminary data on pharmacodynamics and pharmacokinetics, not efficacy comparisons. - They are typically conducted very early in drug development, examining if the drug behaves as expected in humans. *Phase 2* - **Phase 2 trials** evaluate the efficacy and further assess safety of a new treatment in a larger group of patients (tens to hundreds). - While they assess efficacy, they usually don't involve direct comparison with an established standard therapy on the scale implied by the question, which is typically reserved for Phase 3. *Phase 1* - **Phase 1 trials** primarily focus on safety, dosage, and side effects in a small group of healthy volunteers or patients with the condition (20-100 subjects). - These trials are not designed to assess a treatment's efficacy against an existing therapy. *Phase 4* - **Phase 4 trials** occur after a drug or device has been approved and marketed, focusing on long-term safety, effectiveness in diverse populations, and new indications. - The described pump "is not yet available," indicating it has not reached the market and thus is not in Phase 4.

RCTs US Medical PG Question 2: A researcher is conducting a study to compare fracture risk in male patients above the age of 65 who received annual DEXA screening to peers who did not receive screening. He conducts a randomized controlled trial in 900 patients, with half of participants assigned to each experimental group. The researcher ultimately finds similar rates of fractures in the two groups. He then notices that he had forgotten to include 400 patients in his analysis. Including the additional participants in his analysis would most likely affect the study's results in which of the following ways?

• A. Wider confidence intervals of results
• B. Increased probability of committing a type II error
• C. Decreased significance level of results
• D. Increased external validity of results
• E. Increased probability of rejecting the null hypothesis when it is truly false (Correct Answer)

RCTs Explanation: ***Increased probability of rejecting the null hypothesis when it is truly false*** - Including more participants increases the **statistical power** of the study, making it more likely to detect a true effect if one exists. - A higher sample size provides a more precise estimate of the population parameters, leading to a greater ability to **reject a false null hypothesis**. *Wider confidence intervals of results* - A larger sample size generally leads to **narrower confidence intervals**, as it reduces the standard error of the estimate. - Narrower confidence intervals indicate **greater precision** in the estimation of the true population parameter. *Increased probability of committing a type II error* - A **Type II error** (false negative) occurs when a study fails to reject a false null hypothesis. - Increasing the sample size typically **reduces the probability of a Type II error** because it increases statistical power. *Decreased significance level of results* - The **significance level (alpha)** is a pre-determined threshold set by the researcher before the study begins, typically 0.05. - It is independent of sample size and represents the **acceptable probability of committing a Type I error** (false positive). *Increased external validity of results* - **External validity** refers to the generalizability of findings to other populations, settings, or times. - While a larger sample size can enhance the representativeness of the study population, external validity is primarily determined by the **sampling method** and the study's design context, not just sample size alone.

RCTs US Medical PG Question 3: A researcher is trying to determine whether a newly discovered substance X can be useful in promoting wound healing after surgery. She conducts this study by enrolling the next 100 patients that will be undergoing this surgery and separating them into 2 groups. She decides which patient will be in which group by using a random number generator. Subsequently, she prepares 1 set of syringes with the novel substance X and 1 set of syringes with a saline control. Both of these sets of syringes are unlabeled and the substances inside cannot be distinguished. She gives the surgeon performing the surgery 1 of the syringes and does not inform him nor the patient which syringe was used. After the study is complete, she analyzes all the data that was collected and performs statistical analysis. This study most likely provides which level of evidence for use of substance X?

• A. Level 3
• B. Level 1 (Correct Answer)
• C. Level 4
• D. Level 5
• E. Level 2

RCTs Explanation: ***Level 1*** - The study design described is a **randomized controlled trial (RCT)**, which is considered the **highest level of evidence (Level 1)** in the hierarchy of medical evidence. - Key features like **randomization**, **control group**, and **blinding (double-blind)** help minimize bias and strengthen the validity of the findings. *Level 2* - Level 2 evidence typically comprises **well-designed controlled trials without randomization** (non-randomized controlled trials) or **high-quality cohort studies**. - While strong, they do not possess the same level of internal validity as randomized controlled trials. *Level 3* - Level 3 evidence typically includes **case-control studies** or **cohort studies**, which are observational designs and carry a higher risk of bias compared to RCTs. - These studies generally do not involve randomization or intervention assignment by the researchers. *Level 4* - Level 4 evidence is usually derived from **case series** or **poor quality cohort and case-control studies**. - These studies provide descriptive information or investigate associations without strong control for confounding factors. *Level 5* - Level 5 evidence is the **lowest level of evidence**, consisting of **expert opinion** or **animal research/bench research**. - This level lacks human clinical data or systematic investigative rigor needed for higher evidence levels.

RCTs US Medical PG Question 4: You are reading through a recent article that reports significant decreases in all-cause mortality for patients with malignant melanoma following treatment with a novel biological infusion. Which of the following choices refers to the probability that a study will find a statistically significant difference when one truly does exist?

• A. Type II error
• B. Type I error
• C. Confidence interval
• D. p-value
• E. Power (Correct Answer)

RCTs Explanation: ***Power*** - **Power** is the probability that a study will correctly reject the null hypothesis when it is, in fact, false (i.e., will find a statistically significant difference when one truly exists). - A study with high power minimizes the risk of a **Type II error** (failing to detect a real effect). *Type II error* - A **Type II error** (or **beta error**) occurs when a study fails to reject a false null hypothesis, meaning it concludes there is no significant difference when one actually exists. - This is the **opposite** of what the question describes, which asks for the probability of *finding* a difference. *Type I error* - A **Type I error** (or **alpha error**) occurs when a study incorrectly rejects a true null hypothesis, concluding there is a significant difference when one does not actually exist. - This relates to the **p-value** and the level of statistical significance (e.g., p < 0.05). *Confidence interval* - A **confidence interval** provides a range of values within which the true population parameter is likely to lie with a certain degree of confidence (e.g., 95%). - It does not directly represent the probability of finding a statistically significant difference when one truly exists. *p-value* - The **p-value** is the probability of observing data as extreme as, or more extreme than, that obtained in the study, assuming the null hypothesis is true. - It is used to determine statistical significance, but it is not the probability of detecting a true effect.

RCTs US Medical PG Question 5: Which of the following study designs would be most appropriate to investigate the association between electronic cigarette use and the subsequent development of lung cancer?

• A. Subjects with lung cancer who smoke and subjects with lung cancer who did not smoke
• B. Subjects who smoke electronic cigarettes and subjects who smoke normal cigarettes
• C. Subjects with lung cancer who smoke and subjects without lung cancer who smoke
• D. Subjects with lung cancer and subjects without lung cancer
• E. Subjects who smoke electronic cigarettes and subjects who do not smoke (Correct Answer)

RCTs Explanation: ***Subjects who smoke electronic cigarettes and subjects who do not smoke*** - This design represents a **cohort study**, which is ideal for investigating the **incidence** of a disease (lung cancer) in groups exposed and unexposed to a risk factor (electronic cigarette use). - By following these two groups over time, researchers can directly compare the **risk of developing lung cancer** in e-cigarette users versus non-smokers. *Subjects with lung cancer who smoke and subjects with lung cancer who did not smoke* - This option incorrectly compares two groups both with lung cancer, where the exposure to smoking can either be **electronic or traditional cigarettes,** but does not provide a control group without lung cancer to assess the association. - This design would not allow for the calculation of an **incidence rate** or a **relative risk** of lung cancer development specific to electronic cigarette use. *Subjects who smoke electronic cigarettes and subjects who smoke normal cigarettes* - This design compares two different types of smoking, which might be useful for comparing their relative risks but doesn't include a **non-smoking control group** to establish the absolute association with electronic cigarettes. - While it could show if e-cigarettes are "safer" than traditional cigarettes, it wouldn't directly answer whether e-cigarettes themselves **cause lung cancer**. *Subjects with lung cancer who smoke and subjects without lung cancer who smoke* - This describes a **case-control study** but focuses on smoking in general rather than specifically electronic cigarettes, which is the independent variable of interest. - While valuable for identifying risk factors, it would need to specifically differentiate between **electronic cigarette smokers** and other smokers to answer the question adequately. *Subjects with lung cancer and subjects without lung cancer* - This general description of a **case-control study** is too broad; it does not specify the exposure of interest, which is electronic cigarette use. - To be relevant, the study would need to gather data on **electronic cigarette use** in both the lung cancer group and the non-lung cancer control group.

RCTs Flashcard 1 of 5

Question: Are Randomization and Concealment the same? _____

Answer: nah bruh

RCTs Flashcard 2 of 5

Question: Randomization is critical in preventing _____

Answer: confounding bias

RCTs Flashcard 3 of 5

Question: The number needed to treat (NNT) is equal to _____

Answer: 1/ARR

RCTs Flashcard 4 of 5

Question: Phase III

Answer: Large numbers of people with the disease of interest; RCT format

Extra Information: Compares new treatment to existing standard of care

RCTs Flashcard 5 of 5

Question: Are Randomization and Concealment the same? _____

Answer: nah bruh

Extra Information:  https://onlinemeded.org/spa/epidemiology-and-stats/bias/acquire?ref=anki