American Board of Surgery Qualifying Exam (ABS QE) Practice Test

What does the log-rank test primarily compare?

1. Blood pressure levels between groups

2. Survival analysis curves among multiple groups

3. Frequency of adverse events in clinical trials

4. Quality of life scores in elderly populations

The correct answer is: Survival analysis curves among multiple groups

The log-rank test is a statistical method specifically designed to compare survival distributions between two or more groups. It assesses whether there are statistically significant differences in the probability of survival over time, which is crucial in survival analysis. By analyzing the time until an event occurs (such as death or recurrence of a disease), the log-rank test produces insights into how different groups may experience variations in survival rates based on treatment or other factors. The application of the log-rank test is particularly relevant in clinical trials and epidemiological studies, where understanding these differences can guide future treatment decisions and reveal the efficacy of interventions. Its primary focus is on the survival curves, allowing researchers to visualize and quantify the differences between them using Kaplan-Meier estimates. In contrast, the other options involve different types of comparisons not suitable for the log-rank test. Blood pressure levels pertain to continuous data comparisons, while adverse event frequencies deal with categorical outcomes. Quality of life assessments, although relevant in healthcare, do not necessarily involve time-to-event data that the log-rank test evaluates. This reinforces the specificity of the log-rank test to survival analysis among multiple groups.