Study Questions:
1. What is the association between cardiovascular prognostic factors and mortality in Medicare beneficiaries with atrial fibrillation?
2. What is the association between cardiovascular prognostic factors imputed from Medicare part A data and mortality in Medicare beneficiaries with atrial fibrillation?
3. What is the association between the Deyo-modified Charlson index andmortality in Medicare beneficiaries with atrial fibrillation?

Objectives:
1. To quantify the association between common cardiovascular prognostic factors (eg. hypertension and diabetes) and mortality in patients who have atrial fibrillation.
2. To determine how well cardiovascular prognostic factors imputed from administrative data predict mortality.
3. To quantify the accuracy of using the Deyo-modified Charlson index for mortality risk adjustment and to compare it to alternative schemes (e.g. A. Elixhauser, 1998).

Study methodology:
The study will use an existing database, the National Registry of Atrial Fibrillation (NRAF). With funding from the Agency for Healthcare Research and Quality (AHRQ) and in collaboration with the Medicare Peer Review Organization (PROs), we assembled the NRAF dataset, a registry of Medicare patients who have chronic atrial fibrillation and a high mortality rate (approximately 19% in year 1). The NRAF dataset contains both administrative and chart-review data on 3932 Medicare beneficiaries.