Between 1999 and 2013, the adjusted rates of hospitalization for atrial fibrillation increased nearly 1 percent year per year among Medicare fee-for-service beneficiaries, while the median Medicare inpatient expenditure per beneficiary increased from $2,932 to $4,719 per stay.

During the same time period, the rate of inpatient mortality during atrial fibrillation hospitalization increased 4 percent per year, the rate of 30-day readmission decreased by 1 percent per year, the rate of 30-day mortality decreased by 0.4 percent per year and the rate of 1-year mortality decreased by 0.26 percent per year.

Lead researcher James V. Freeman, MD, MPH, MS, of the Yale University School of Medicine, and colleagues published their results online in Circulation on Feb. 1.

At least 2.3 million people in the U.S. have atrial fibrillation, according to the researchers, making it among the most common cardiac diseases. The researchers noted that between 1999 and 2013, treatment advanced for atrial fibrillation, including the widespread adoption of atrial fibrillation ablation. Approximately 50,000 people in the U.S. each year undergo atrial fibrillation ablation, which has been shown to improve symptom burden and quality of life.

For this analysis, the researchers examined CMS data and examined all Medicare fee-for-service beneficiaries who had atrial fibrillation between 1999 and 2013.

The rates of observed atrial fibrillation hospitalization increased from 668 per 100,000 person-years in 1999 to 700 per 100,000 person-years in 2013. Higher rates were observed in the Midwest, Mid-Atlantic and South.

Meanwhile, the risk of atrial fibrillation increased an average of 0.85 percent per year after adjusting for age, sex, race and comorbidities. The increase was similar in age, sex and race strata, although the increase was highest among adults who were 85 years old or older.

In addition, in-hospital mortality from atrial fibrillation decreased from 1.6 percent in 1999 to 1.3 percent in 2013, while the age, sex, race and comorbidity adjusted rate of in-hospital mortality decreased by an average of 3.87 percent per year.

The 30-day mortality rate increased from 3.9 percent in 1999 to 4.9 percent in 2013, while the 1-year mortality rate increased from 13.7 percent to 16.4 percent. However, after adjusting for age, sex, race and comorbidities, the 30-day mortality rate decreased 0.4 percent per year and the 1-year mortality rate decreased 0.26 percent per year.

Further, 30-day readmissions decreased from 15.3 percent in 1999 to 13.9 percent in 2013. The researchers noted decreases in the rates of readmission for stroke and heart failure, but rates of readmission for atrial fibrillation or bleeding did not change. The 30-day readmission rate decreased by 0.96 percent per year after adjusting for age, sex, race and comorbidities.

The researchers noted a few limitations of the study, including that they only examined Medicare fee-for-service beneficiaries, so the results might not be generalizable to adults with Medicare Advantage or the broader U.S. population. They also used administrative claims to identify atrial fibrillation and could not confirm the diagnosis with electrocardiograms or cardiac monitoring. In addition, they only evaluated hospitalizations and did not examine observation stays and outpatient visits.

“Taken together, our results offer a comprehensive examination of contemporary [atrial fibrillation] treatment patterns and outcomes and show that patients are hospitalized more frequently, especially at extremes of age, and treated more intensively and expensively,” the researchers wrote. “However, this treatment has resulted in lower rates of in-hospital death, readmission, and long-term mortality, though the mortality benefits may not be conferred on the very elderly.”