Seasonal Cycle and Relationship of Seasonal Rhino- and Influenza Virus Epidemics With Episodes of Asthma Exacerbation in Different Age Groups

Abstract

PurposeSeasonal variations in asthma exacerbation (AE) are associated with respiratory virus outbreaks and the return of children to school after vacation. This study aims to elucidate the period, phase, and amplitude of seasonal cycles of AE in 5 different age groups with regard to rhino- and influenza virus epidemics in Korea.MethodsThe number of daily emergency department (ED) visits for AE in all age groups of Korea and the nationwide weekly incidence of rhino- and influenza virus, were obtained for 2008-2012. Fourier regression was used to model rhythmicity, and the Cosinor method was used to determine the amplitude and phase of the cycles in each age group. The cross-correlation function (CCF) between AE and the rhino- and influenza virus epidemics was also calculated.ResultsThere were 157,559 events of AE (0.62 events/1,000 individuals/year) during the study period. There were spring and fall peaks of AE in children and adults, but only 1 winter peak in the elderly. The amplitude of the AE peak in infants was higher in spring than in fall (9.16 vs 3.04, P<0.010), and the fall peak was approximately 1 month later in infants than in school children (October 11 vs November 13, P<0.010). The association between AE and rhinovirus was greatest in school children (rho=0.331), and the association between AE and influenza virus was greatest in those aged ≥60 years (rho=0.682).ConclusionsThe rhythmicity, amplitude, and phase of the annual cycle of AE differed among different age groups. The patterns of AE were related to the annual rhino- and influenza virus epidemics.

Short-term effects of multiple outdoor environmental factors on risk of asthma exacerbations: Age-stratified time-series analysis

“…Moreover, IFV is often concurrent with AE events, 3 especially in older subjects. 4 However, we found that the effect of influenza on AEs was greatest in adults but not the elderly. This might be because the nationwide influenza vaccination program in Korea and Lag day 4, 4 days previously.…”

“…Data were analyzed with a Fourier regression model to characterize the seasonal dynamics of environmental changes. 4 All analyses were conducted with R software (version 3.5.1). A P value of less than .05 was considered statistically significant.…”

“…Detailed descriptions of these data were provided previously. 4 The database included all AE events requiring admission to an emergency department that were coded by ICD-10 as J45 (asthma) or J46 (status asthmaticus). 17 Subjects were classified into 5 age groups: younger than 2 years (infants), 2 to 5 years (preschool children), 6 to 17 years (schoolaged children), 18 to 59 years (adults), and 60 years or older (elderly).…”

“…Weekly nationwide viral respiratory tract detection rates were calculated from the results of respiratory virus PCR from the Korea Centers for Disease Control and Prevention. 4…”

“…Key words: Asthma exacerbation, air pollutant, weather condition, aeroallergen, human rhinovirus, influenza virus Asthma exacerbations (AEs) are especially common in young and elderly subjects 1 and are associated with seasonal variations of environmental factors, such as weather conditions, aeroallergens, and ambient air pollution. 2 There is an autumnal peak of AEs in children caused by human rhinovirus (HRV) and a winter peak in elderly subjects from the United States 3 and Korea 4,5 caused by the influenza virus (IFV). Ambient air pollutants, [6][7][8] aeroallergens, 9 and certain weather conditions.…”