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Hazard Ratios and Alternative Effect Measures: An Applied Illustration
Chase D Latour1,2, I-Hsuan Su1, Megan Delgado1
1Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Pharmacoepidemiology and Drug Safety
|August 30, 2024
Summary
Hazard ratios (HRs) can be misleading for treatment effects. This study contrasts HRs with risk ratios in metastatic colorectal cancer, highlighting the need for multiple measures due to nonproportional hazards.
Area of Science:
- Oncology
- Biostatistics
- Clinical Trials
Background:
- Hazard ratios (HRs) are commonly used but have limitations in quantifying treatment effects with censored data.
- Alternative effect measures are often more interpretable but less frequently reported.
Purpose of the Study:
- To contrast HRs with alternative effect measures using real clinical trial data.
- To illustrate the challenges in interpreting HRs, especially with nonproportional hazards.
Main Methods:
- Analysis of data from two randomized clinical trials for metastatic colorectal cancer.
- Comparison of panitumumab plus chemotherapy versus chemotherapy alone.
- Estimation of HR and risk ratio for progression-free survival (PFS).
- Examination of cumulative incidence, hazards curves, and survival times.
Main Results:
- HR suggested a treatment benefit (0.82), while the risk ratio indicated no significant effect (0.99).
- Substantial nonproportional hazards were observed, with panitumumab initially reducing hazards but increasing them later.
- Despite similar cumulative incidence, panitumumab-treated patients had longer PFS.
Conclusions:
- The study highlights difficulties in interpreting HRs, particularly with violations of proportional hazards.
- Quantifying treatment effects using multiple measures is valuable for accurate clinical interpretation.
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