BOSTON -- Winter is the season with a higher incidence of asthma exacerbations requiring hospitalization across all regions of the U.S. and age groups of adults, researchers reported here.
Incidence of asthma-related hospitalizations was significantly higher in the winter months (peak/low ratio 1.22, 95% CI 1.21-1.22, P<0.0001) compared to the rest of the year, reported Pragya Shrestha, MD, of Reading Health System in Pennsylvania, in a at the American College of Allergy, Asthma & Immunology annual meeting here.
During her emergency department rotation, Shrestha said she observed a lot of patients with asthma exacerbations in the winter season. Prior research had shown a similar trend, she said, but the results were somewhat varied.
"I wondered does asthma have seasonality, and I wanted to shed some light on the inconsistencies of previous studies," Shrestha told MedPage Today.
She and her group examined data from the National Inpatient Sample, consisting of patients age 18 years or older who had been admitted to the hospital for asthma (defined as the first three diagnoses using ICD-9-CM codes). Seasons were defined as spring (March-May), summer (June-August), fall (September-November) and winter (December-February). Patients were stratified by age groups, consisting of adults 18-34, 35-64, and 65+.
From 2009 to 2011, there were 18,428,067 asthma-related hospitalizations in the U.S., with the highest proportion occurring in the southern region of the country (33.9%).
Asthma-related inpatient mortality also peaked during the winter months (peak/low ratio 1.56, 95% CI 1.46-1.66) with peak mortality in February, the researchers reported.
While asthma-related hospitalizations were highest across all age groups and regions during the winter months, incidence of asthma-related mortality varied when it was stratified based on age groups:
- Ages 18-34: November
- Ages 35-64: March
- Ages 65+: February
Shrestha emphasized the difference in asthma-related mortality by age groups at the presentation, and suggested this would be a direction for future research. Discrepancy in mortality peaks across ages might relate to different triggers and mechanisms associated with exacerbations for different groups, and a better understanding of these trends could aid in the treatment and prevention of asthma-related hospitalizations and mortality, she said.
Primary Source
American College of Allergy, Asthma & Immunology
Shesthra P, et al "Seasonal and regional variation of asthma-related hospitalization and mortality in the United States" ACAAI 2017; Abstract OR047.