American Journal of Epidemiology Advance Access originally published online on July 20, 2005
American Journal of Epidemiology 2005 162(5):487-490; doi:10.1093/aje/kwi221
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PRACTICE OF EPIDEMIOLOGY |
Performance of Floating Absolute Risks
From the Department of Biostatistics, Vanderbilt University, Nashville, TN
Reprint requests to Dr. Patrick G. Arbogast, Department of Biostatistics, S-2323 Medical Center North, Vanderbilt University, Nashville, TN 37232-2158 (e-mail: patrick.arbogast{at}vanderbilt.edu).
A recent investigation of hormone replacement therapy and breast cancer risk used a method called "floating absolute risks" (FARs) to compute confidence intervals for relative hazards. This method has been used in other medical studies and has received controversy. This controversy stems from the correct implementation of this method. However, there has been no direct comparison of the FAR method, as it is sometimes incorrectly applied and reported, with the conventional approach for computing confidence intervals from proportional hazards regression. In this paper, the author reports simulation results comparing these two methods and demonstrates that the FAR method, when applied incorrectly, can produce confidence intervals that are substantially too narrow.
confidence intervals; epidemiologic methods; hazard rate; proportional hazards models; regression; relative risk; survival analysis
Abbreviations: FAR, floating absolute risk; SEE, standard error estimate