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

What is a key feature of the Cox model in survival analysis?

1. It categorizes patients into risk groups

2. It adjusts for potential confounders

3. It does not consider time as a variable

4. It requires complete data without censoring

The correct answer is: It adjusts for potential confounders

The Cox model, also known as the Cox proportional hazards model, is a fundamental tool in survival analysis primarily due to its ability to adjust for potential confounders. This feature allows researchers to account for various covariates when estimating the hazard function, which is the rate at which events occur (like death or failure) over time. By including covariates in the model, the Cox model helps isolate the effect of specific factors on survival while controlling for others, providing a clearer understanding of the relationships in the data. This model does not categorize patients into distinct risk groups; instead, it provides a continuous measure of risk based on the covariates. Furthermore, the Cox model fundamentally incorporates time as a variable, allowing it to analyze how risk changes over time. Additionally, while the ideal use of the Cox model is with complete data, it is robust against right-censoring, meaning it can handle situations where the event of interest has not occurred for some subjects during the observation period. Thus, the capacity to adjust for confounders truly stands out as a key feature of the Cox model in survival analysis.