Abstract 8886: Seasonal Variation of Atrial Fibrillation Hospitalizations

Abstract

Introduction: Atrial Fibrillation (AF) hospitalization has emerged as an important clinical end point to assess outcomes of AF. There has been an interest in seasonal variation of cardiovascular hospitalizations.We assessed seasonal variation in hospitalizations for AF from a large national hospitalization database in the past decade. Methods: The Nationwide Inpatient Sample database was used to estimate the annual number of hospitalizations with AF from 2000-2008.Identification of AF related hospitalizations was based on the designation of the International Classification of Diseases (9th Edition) Clinical Modification (ICD-9-CM) diagnosis code 427.31 (AF) as the principal discharge diagnosis. The frequency of hospitalization for each month cumulative over 8 years was calculated and divided by number of days in that month to obtain the mean hospitalizations per day for each month. All calculations were carried out using the weighted estimates approximating nationwide population estimates Results: An estimated 2909423 hospitalizations with primary diagnosis of AF occurred in the United States from the beginning of the calendar year 2000 to the end of the calendar year 2008. The number of hospitalizations per day in each month is shown in Figure 1.The number of hospitalization was maximum in the winter months and minimum in summer months. Specifically, the mean number of hospitalization each day (averaged over 8 years) was least in July (7532). There was a rising trend from July to February. The average number of hospitalization was highest in February (8260); thereafter, the hospitalization rate dropped to a nadir in July. Conclusion: We identified for the first time in United States an impressive pattern of seasonal variation in hospitalizations for AF.Further efforts must be made to identify triggers and methods to prevent AF hospitalizations and reduce its burden on health care system.