RCTs — MCQs

A research consortium is studying a new vaccine for respiratory syncytial virus (RSV) in premature infants compared to the current standard of care. 1000 infants were randomized to either the new vaccine group or the standard of care group. In total, 520 receive the new vaccine and 480 receive the standard of care. Of those who receive the new vaccine, 13 contract RSV. Of those who received the standard of care, 30 contract RSV. Which of the following is the absolute risk reduction of this new vaccine?

BACKGROUND: Aldosterone blockade reduces mortality and morbidity among patients with severe heart failure. We conducted a double-blind, placebo-controlled study evaluating the effect of eplerenone, a selective aldosterone blocker, on morbidity and mortality among patients with acute myocardial infarction complicated by left ventricular dysfunction and heart failure. METHODS: Patients were randomly assigned to eplerenone (25 mg per day initially, titrated to a maximum of 50 mg per day; 3,319 patients) or placebo (3,313 patients) in addition to optimal medical therapy. The study continued until 1,012 deaths occurred. The primary endpoints were death from any cause, death from cardiovascular causes, hospitalization for a heart failure exacerbation, acute myocardial infarction, stroke, or ventricular arrhythmia. RESULTS: During a mean follow-up of 16 months, there were 478 deaths in the eplerenone group and 554 deaths in the placebo group (relative risk, 0.85; 95% confidence interval, 0.75 to 0.96; p=0.008). Of these deaths, 407 in the eplerenone group and 483 in the placebo group were attributed to cardiovascular causes (relative risk, 0.83; 95% confidence interval, 0.72 to 0.94; p=0.005). The rate of the other primary endpoints, death from cardiovascular causes or hospitalization for cardiovascular events, was reduced by eplerenone (relative risk, 0.87; 95% confidence interval, 0.79 to 0.95; p=0.002), as was the secondary endpoint of death from any cause or any hospitalization (relative risk, 0.92; 95% confidence interval, 0.86 to 0.98; p=0.02). There was also a reduction in the rate of sudden death from cardiac causes (relative risk, 0.79; 95% confidence interval, 0.64 to 0.97; p=0.03). The rate of serious hyperkalemia was 5.5% in the eplerenone group and 3.9% in the placebo group (p=0.002), whereas the rate of hypokalemia was 8.4% in the eplerenone group and 13.1% in the placebo group (p<0.001). Which of the following represents the relative risk reduction (RRR) in all-cause mortality, the primary endpoint, in patients supplemented with eplerenone?

In a randomized controlled trial studying a new treatment, the primary endpoint (mortality) occurred in 14.4% of the treatment group and 16.7% of the control group. Which of the following represents the number of patients needed to treat to save one life, based on the primary endpoint?

A researcher is investigating the risk of symptomatic intracerebral hemorrhage associated with tissue plasminogen activator (tPA) treatment in severe ischemic stroke. The outcomes of a large randomized controlled trial of ischemic stroke patients, some of whom were randomized to tPA, is shown: Symptomatic intracerebral hemorrhage No symptomatic intracerebral hemorrhage Received tPA 12 188 Did not receive tPA 25 475 Based on this data, how many patients with severe ischemic stroke would need to be treated with tPA, on average, to contribute to one case of symptomatic intracerebral hemorrhage?

An investigator is studying the efficacy of a new bisphosphonate analog in preventing hip fractures in patients above 60 years of age with risk factors for osteoporosis but no confirmed diagnosis. Participating patients were randomized to either pharmacologic therapy with the new bisphosphonate analog or a placebo. The results show: Hip fracture No hip fracture Pharmacologic therapy 3 97 No pharmacologic therapy 10 190 Based on this information, which of the following best represents the proportionate reduction in the risk of hip fractures brought about due to pharmacologic therapy, in comparison to the control group?

A new formula for an anti-wrinkle cream is being tested for efficacy in a group of 362 healthy 40- to 60-year-old female volunteers. The marketing team randomizes the volunteers. Half receive the new formula and the other half of the volunteers receive the original formula. The mean age in the test group is 48 (95% CI 42-56), and the average age of the control group is 49 (95% CI 42-55). The volunteers are unaware of which formula they receive. The research and development team then compares before and after photographs of the volunteers following 6 weeks of at home application twice daily. For simplicity, the marketing team labels the photographs with "new formula" or "original formula." 98% of volunteers in the test group complete the study, and 97% of volunteers in the control group complete the study. The researchers conclude that there is improved wrinkle reduction with 6 weeks of use of the new formula. Which of the following potential biases most likely impacted this conclusion?

In 2006, three researchers from North Carolina wanted to examine the benefits of treating the risk of suicidality in children and adolescents by looking at randomized, multicenter, controlled trials of sertraline usage compared to placebo. Their analysis found clinically significant benefits of the drug and a positive benefit-to-risk ratio for sertraline in adolescents with major depressive disorder. They also found that 64 depressed children and adolescents need to receive the drug for 1 extra patient to experience suicidality as an adverse outcome. In other words, if 64 treated individuals received sertraline, some would experience suicidality due to their illness, some would not experience suicidality, and 1 individual would become suicidal due to the unique contribution of sertraline. Which of the following statements is true for this measure (defined as the inverse of the attributable risk), which aims to describe adverse outcomes this way?

A randomized, controlled trial was undertaken by a team of clinical researchers to evaluate a new drug for the treatment of cluster headaches. This type of headache (that mostly affects men) is characterized by excruciating pain on 1 side of the head. After careful randomization and controlling for all of the known confounders, a total of 200 patients with cluster headaches were divided into 2 groups. The first group of study participants received 40 mg of the new drug, X, in the form of a powder mixed with water. The second group received 80 mg of verapamil (a calcium channel blocker that is commonly prescribed for cluster headaches) in the form of a labeled pill. Participants from both groups were mixed together in rooms designated for drug research purposes and could communicate freely. After the study period has finished without any loss to follow-up or skipped treatments, the outcome (pain alleviation) was assessed by trained researchers that were blinded to treatment assignment. Study results have shown that the new drug is more efficacious than current gold standard by both clinically and statistically significant margin. Therefore, the investigators concluded that this drug should be introduced for the treatment of cluster headaches. However, their conclusions are likely to be criticized on the grounds of which of the following?

The VALIANT trial compared the effect of captopril and valsartan on mortality in patients with myocardial infarction complicated by heart failure. Subjects were randomly assigned to treatment with either captopril or valsartan and subsequently followed for 2 years. The primary endpoint was death from any cause. The study concluded that valsartan was as effective as captopril in patients who are at high risk for cardiac events after an MI. Which of the following describes this type of study?

A pharmaceutical company is studying the effect of a novel compound that they have discovered to treat osteoporosis. They perform a randomized controlled clinical trial to study if this compound has an effect on the incidence of hip fractures among osteoporotic patients. They find that there is no statistical difference between the experimental and control groups so they do not pursue the compound further. Two years later, a second team tests the same compound and finds that the compound is effective, and follow up studies confirm that the compound has a statistically significant effect on fracture risk. Which of the following most likely describes what occurred in the first study?