In this study of U.S. hospitalization rates and AF rhythm control treatment patterns over time, significant changes were observed in the years following the 2002 publication of the AFFIRM and RACE trials. Reversing a previously reported,5
prolonged trend that continued from 1998–2002, hospitalizations with AF as the principal diagnosis declined at a rate of 2% per year from 2002 to 2004, in parallel with a decline in electrical cardioversions. Hospitalization rates began increasing again in 2005 and 2006, during which time robust growth was observed in catheter ablations with AF as the principal diagnosis. Given that catheter ablation for patients with a diagnosis of AF is performed significantly more frequently at hospitals with larger bed-sizes,14
it is of interest that the increase in AF hospitalization rates in 2005 and 2006 was observed primarily at teaching and metropolitan hospitals. Outpatient use of oral antiarrhythmic drugs also changed during this timeframe, with the number of prescriptions plateauing from 2002 to 2005 after a period of sustained growth between 1998 and 2002.
The current data extend previously documented increases in the number of hospitalizations for AF4,5
and AF catheter ablations,14,15
as well as previously observed prescription growth for Class IC and Class III AADs and declining use of Class IA AADs.16,17
This study expands on historical trends by providing information on how these AF management patterns were affected following the publication of AFFIRM and RACE. The current data show a clear change in AF hospitalizations and rhythm control treatment patterns following the publication of AFFIRM and RACE in 2002. In particular, elective admissions for AF management and utilization of inpatient cardioversion declined from 2002–04.
Some of our findings, particularly those related to antiarrhythmic drug utilization, are similar to those reported by the Euro Heart Survey18,19
and the RecordAF20,21
However, these registries were primarily cross-sectional in nature and therefore do not permit the longitudinal perspective contained in the current report.
Other observational databases have provided information on AF treatment patterns in the U.S. since AFFIRM and RACE, and suggest an impact of these trials on AF treatment patterns. Similar changes in Class IA, IC, and III antiarrhythmic drug prescriptions were reported between the 12-month periods ending June 2003 and June 2004.23
In smaller observational studies from two university medical centers and in selected patient populations in isolated U.S. states or Canadian provinces, usage of both cardioversion and AADs was also reported to decline after the publication of AFFIRM and RACE.24,25
However, data are not available on whether these declines were temporary or sustained, nor is this information nationally representative. In addition, previous publications do not provide information on trends in AF hospitalizations following AFFIRM and RACE, yet hospitalization is the largest single driver of AF treatment cost.
Given the magnitude of AF hospitalization treatment costs, this post-AFFIRM/RACE decline in AF-related hospitalizations is intriguing not only from a clinical, but also from a health economic perspective. Analysis of the AFFIRM trial demonstrated that a rate control strategy was clinically equivalent (to marginally more effective) and significantly less costly than a rhythm control strategy using AADs.26
Whether the apparent shift back towards rhythm control interventions seen in the later years of our analysis represents cost-effective care remains to be established.
The present data may also have implications for the use of hospitalization as an endpoint in AF clinical trials. Although post hoc analysis from the AFFIRM trial demonstrated that patients hospitalized during follow-up faced an increased risk of subsequent mortality,27
there are potentially many factors that may influence the likelihood of AF hospitalizations, including the local availability of outpatients services, the financial incentives and disincentives of differing payment models, physician training and habits, and patient preferences and expectations. Our data suggest that patients and physician attitudes toward rhythm vs. rate control likely also influence hospitalization rates.
There are a number of limitations associated with this analysis. Given that NIS is based on claims data from a sampling of U.S. hospitals, figures for number of hospitalizations and procedures are necessarily estimates rather than exact counts. Since HCUPNet provided information only on hospitalization and inpatient procedures, this study does not capture information on non-pharmacologic outpatient rhythm management of AF, and is therefore an incomplete picture of rhythm control treatment patterns. Some trends observed in inpatient treatment patterns may be related to shifting of care to the outpatient setting. There are no specific ICD-9 codes for AF ablation or AF cardioversion, complicating the estimation of the inpatient volume for these procedures. We therefore reported these principal procedures for any principal diagnosis of AF, but recognize that these designations may not always be accurate. We have not examined admission-level data to assess factors associated with these trends in a multivariate context. For IMS National Prescription Audit™ data, prescription data are not specific for the AF diagnosis, so total prescription numbers also represent use for other diagnoses in addition to AF, though we believe AF is the most common indication for each of these drug classes. Finally, our attribution of the temporal trends we observed to the AFFIRM and RACE trials is speculative. These observed changes cannot be attributed with certainty to the publication of AFFIRM and RACE, as multiple factors may drive changes in clinical practice, including the dissemination of other scientific evidence, commentary from opinion leaders, changing guidelines, media coverage, and various other factors.