It is important also to acknowledge potential study limitations. This study was retrospective and relied on medical record information accrued over a 4-decade period. Also, for a medical condition to be ascertained, it had to come to medical attention, be diagnosed by a physician, and documented in the patient's medical records. We acknowledge that medical practices may have changed over this time period. In addition, cardiovascular events that were unrecognized by patients and/or health professionals would not have been ascertained. This may underestimate the number or timing of cardiovascular events, particularly silent MI or angina. Finally, we cannot rule out the possibility of nondifferential ascertainment of cardiovascular events. It is possible, for example, that mild angina is less likely to be reported among patients with RA compared with non-RA subjects because of the high frequency of analgesic use among patients with RA. This may result in an underestimate of the risk of angina in patients with RA compared with non-RA subjects. However, the comprehensive medical records linkage system of the Rochester Epidemiology Project (covering inpatient and outpatient care from all local providers) allowed us to access complete health care information for a median of 14.1 years of followup. Because in this geographically well-defined population almost all residents come to medical attention in any 3-year period (12), differential ascertainment bias is less likely to affect our results. Also, the study population was composed largely of white individuals, which may limit the generalizability of the results to more diverse populations. Finally, although our analyses did not demonstrate a significant difference in mortality between CHF patients with and those without RA, our study did not have adequate power to detect small, but possibly clinically important, differences in mortality between these groups.