METHODS
We analyzed data on deaths in the U.S. from 1999 to 2019 in which AF and cancer were listed as either an underlying or contributing cause of death. Data were sourced from the CDC WONDER database.7 The study focused on individuals aged 25 years and older, identified by the International Classification of Diseases, Tenth Revision codes I48 for AF and C00-C97 for cancer. To investigate national trends in AF and cancer-related mortality, we calculated crude and age-adjusted mortality rates (AAMRs) per 100,000 individuals over the study period. Crude mortality rates were obtained by dividing the annual number of deaths by the respective U.S. population for each year, while AAMRs were standardized to the 2000 U.S. population for consistency across years.8 We reported 95% confidence intervals (CIs) for all mortality rates. Trend analyses were conducted using the Joinpoint Regression Program (Version 5.2.0, National Cancer Institute), which calculates annual percent change (APC) and average annual percent change (AAPC) along with corresponding 95% CIs. A trend was classified as increasing or decreasing if its slope significantly differed from zero, with statistical significance assessed using two-tailed t-tests. A p-value ≤ 0.05 was considered statistically significant.