Asthma-Related Emergency Department Visits in Texas: Associations with Viruses and Allergenic Pollen

ABSTRACT

Rationale Asthma exacerbations cause many emergency department visits but much remains unknown about the role of seasonal environmental triggers including viruses and allergenic pollen. A better understanding of these triggers and the role of regionally-important pollen types such as ‘mountain cedar' (in the Cupressaceae family) in Texas could help prioritize public health interventions. Methods: We acquired data on all emergency department visits in Texas from 2015–2020 where asthma was the primary ICD diagnosis code. Emergency department visit rates were compared to concentrations of several pollen types (Cupressaceae, trees, and other plants), and to test positivity of viruses (rhinovirus, coronavirus, RSV, and influenza) among populations living near eight pollen monitoring stations. We analyzed these relationships with age-stratified Poisson regression analyses in a distributed lag framework. Results: Young children had high asthma-related emergency department rates (22.4 visits/1,000,000 person-days), which were explained by viruses (70.4±2.6%), Cupressaceae pollen (0.4±0.1%), and tree pollen (0.9±0.4%). School-aged children also had high rates (19.7 visits/1,000,000 person-days), which were attributed to viruses (61±2%), Cupressaceae pollen (0.5±%) and tree pollen (1.5±0.1%). Adults had lower rates (7.6 visits/1,000,000 people/day) which were attributed to viruses (38±2%), Cupressaceae pollen (0.5±0.1%) and tree pollen (2.5±0.2%). Rates attributed to pollen exhibited spatio-temporal patterns;for example, Cupressaceae accounted for 7% of adult cases in January in Austin, but <1% in Houston. Similarly, for adults in Houston tree pollen accounted for 2% of cases annually but 19% in March. Conclusions: These findings demonstrate the consequences of regionally important allergenic plants to respiratory health and spatio-temporal patterns of emergency department visits.