Akintoye E, et al. - This study hypothesized significant seasonal variation in the heart failure (HF) hospitalization outcomes in the U.S. Findings showed that hospitalization outcomes were worse in Winter but better in Summer among HF patients in the U.S.

Methods

• Researchers used data from the National Inpatient Sample (2011-2013) to classify seasonal variation based on meteorological classification of Northern Hemisphere–Spring, Summer, Fall, & Winter.
• The analysis was conducted via multivariable-adjusted mixed-effect model.

Results

• Data showed that an estimated 2.8 million adults were hospitalized for HF in the U.S. from 2011 to 2013.
• Researchers noted that, of all hospitalizations, admissions were highest in Winter (27%), followed by Spring (26%), Fall (24%), and Summer (23%).
• They also observed that the overall mortality rate was 3.1% and, compared with Spring, there was significantly lower mortality in Summer (odds ratio [OR]: 0.95, 95% CI: 0.91-0.99) and Fall (OR: 0.94, 95% CI: 0.89-0.98), but the highest mortality was in Winter (OR: 1.06, 95% CI: 1.02-1.11).
• Findings demonstrated that mean length of stay and median cost of hospitalization were highest in Winter (5.3 days, USD7459, respectively) and lowest in Summer (5.1 days, USD7181, respectively).
• However, results highlighted that age and sex differences existed (e.g. seasonal variation in inpatient mortality was only significant for patients age ≥65 years, and, compared with the Spring season, males had higher risk of inpatient mortality in Winter (OR: 1.10, 95% CI: 1.04-1.17) and females had lower risk of inpatient mortality in Summer (OR: 0.94, 95% CI: 0.88-1.00) and Fall (OR: 0.92, 95% CI: 0.87-0.98).