Author Affiliations: Departments of Medicine (Dr Parakh) (email@example.com) and Mental Health and Biostatistics (Dr Stuart), Johns Hopkins University School of Medicine, Baltimore, Maryland; and Department of Medicine, University of Minnesota School of Medicine, Minneapolis (Dr Win).
To the Editor: Dr Conen and colleagues1 found that new-onset atrial fibrillation (AF) was associated with mortality in a group of healthy women using Cox proportional hazards models with time-varying covariates. Time-varying analyses more realistically account for risks that change over time, such as AF. This approach is gaining popularity as it allows for individuals to alternate between exposed and unexposed categories, as well as vary in other characteristics during follow-up.
Parakh K, Win S, Stuart EA. Mortality in Women With New-Onset Atrial Fibrillation. JAMA. 2011;306(11):1200-1201. doi:10.1001/jama.2011.1322