Elsevier

Environmental Research

Volume 188, September 2020, 109714
Environmental Research

Heavy precipitation and asthma exacerbation risk among children: A case-crossover study using electronic health records linked with geospatial data

https://doi.org/10.1016/j.envres.2020.109714Get rights and content

Highlights

  • Heavy precipitation events were associated with higher odds of asthma exacerbation among children.

  • Associations between heavy precipitation and asthma exacerbation were restricted to the summer months.

  • We used data from a large electronic health record database to quantify associations of daily heavy precipitation with asthma exacerbation among children.

Abstract

Extreme precipitation events may be an important environmental trigger for asthma exacerbations in children. We used a time stratified case-crossover design and data from a large electronic health record database at the Children's Hospital of Philadelphia (CHOP) to estimate associations of daily heavy precipitation (defined as > 95th percentile of the summertime distribution) with asthma exacerbation among children. We defined control days as those falling on the same day of the week within the same month and year as the case. We restricted our primary analyses to the summer months in years 2011–2016 and used conditional logistic regression models to estimate associations between heavy precipitation and acute asthma exacerbations in both outpatient (primary care, specialty care, and emergency department) and inpatient settings. We investigated numerous individual-level (e.g., age, sex, eczema diagnosis) and environmental measures (e.g., greenspace, particulate matter) as potential effect modifiers. The analysis include 13,483 asthma exacerbations in 10,434 children. Odds of asthma exacerbation were 11% higher on heavy precipitation vs. no precipitation days (95% CI: 1.02–1.21). There was little evidence of effect modification by most measures. These results suggest that heavy summertime precipitation events may contribute to asthma exacerbations. Further research using larger datasets from other health systems is needed to confirm these results, and to explore underlying mechanisms.

Introduction

The earth's climate is becoming wetter and hotter, and even more frequent and intense extreme weather events are projected for the future (IPCC, 2014). Because of biological vulnerabilities related to development, because they may spend more time outdoors than adults, and because effects of early life exposures can have impacts over the life course, it is critical that we understand the impacts of climatic phenomena on children's health (Nicholas et al., 2019; Salas et al., 2019). While a great deal of attention has been given to links between extreme temperatures and health, few studies have quantified the impacts of heavy precipitation. Extreme precipitation events are expected to increase by 0.5%–4% by the end of the 21st century (IPCC, 2014). Quantifying the health impacts of heavy precipitation is important for identifying appropriate intervention strategies to reduce vulnerability, especially among susceptible subpopulations, such as children. Globally, asthma represents the most common chronic disease among children (Ferrante and La Grutta, 2018). Asthma exacerbations are defined by having reduced expiratory airflow function along with one or several of the following symptoms: shortness of breath, cough, wheezing, or chest tightness (Fuhlbrigge et al., 2012). Exacerbations contribute to high healthcare expenditures, diminished quality of life, inability to engage in physical activity, long-term declines in lung function, days missed from school, and sometimes premature death (Nunes et al., 2017).

A variety of environmental factors are posited to be potentially important triggers of an asthma exacerbation. These include environmental cigarette smoke, mold, upper respiratory virus infections (Dougherty and Fahy, 2009), indoor and outdoor air pollutants (O'Connor et al., 2008), and indoor and outdoor allergens (Morgan et al., 2004; Shrestha et al., 2018), among others (Jackson et al., 2011). Only a handful of epidemiologic studies have investigated potential links between heavy precipitation and asthma exacerbation. In Atlanta, GA, thunderstorm events were associated with increased risk of emergency department (ED) visits for asthma—only when there was rainfall during the thunderstorm (Grundstein et al., 2008). In Maryland, extreme precipitation events were associated with higher risk of asthma hospitalizations (Soneja et al., 2016). A larger body of literature has documented spikes of asthma exacerbation following thunderstorms (D'Amato et al., 2017; Silver et al., 2018). The mechanisms underlying these spikes are posited to involve the concentration of pollen grains at ground level and hydration of the pollen grains. Thunderstorms are relatively infrequent; understanding the impacts of heavy precipitation, alone, on asthma exacerbation is important for informing behavioral modifications and interventions. There are a number of mechanisms by which precipitation may affect asthma exacerbations. The osmotic shock (i.e., change to the solute concentration around the cell) may cause pollen grains to rupture suddenly, leading to higher concentrations of aeroallergens (Al-Rubaish, 2007), which are well documented respiratory irritants. Precipitation may increase concentrations of traffic-related pollutants by contributing to higher traffic volumes and congestion, as well as reduced vehicular speed (Kwak et al., 2017). On the other hand, rainfall may have a protective effect, by washing away respiratory irritants, such as particulate matter or pollen (Jackson et al., 2011).

Here, we describe results from a case-crossover study of associations between heavy precipitation and pediatric exacerbation events in the metropolitan Philadelphia area of the United States. The prevalence of asthma among children in Philadelphia, especially in “high risk” areas, has been estimated to be much greater than the national prevalence (Bryant-Stephens et al., 2012; Hill et al., 2016). In our study, we leveraged an electronic health record (EHR) database from the Children's Hospital of Philadelphia (CHOP), a large mid-Atlantic pediatric health system that includes 31 primary care practices and a central ED and inpatient facility. We linked these data with numerous environmental measures, including daily climatological, bioaerosol, and air pollution data; and area-level measures describing neighborhood sociodemographics, traffic volume, and landcover characteristics, among others. The rich dataset allowed us to explore a number of covariates as potential effect modifiers of overall associations between heavy precipitation and asthma exacerbation.

Section snippets

Design

We conducted a time-stratified case-crossover study (Maclure, 1991) of associations between precipitation and asthma exacerbation in children. We defined control days as those falling on the same day of the week within the same month and year as the exacerbation (case) day. For example, if an exacerbation occurred on the first Tuesday in June of 2014, then we compared precipitation amounts on the first Tuesday to all other Tuesdays in June of 2014. The design inherently controls for all

Results

Between 2011 and 2016, in the summer months (June–August), there were 13,483 asthma exacerbations in 10,434 children (Table 1). On average, there were 1.3 exacerbations per child (standard deviation (SD): 0.7). The maximum number of exacerbations per child was 12. The majority (80%) of the children in the database experienced only one exacerbation. Table 2 shows descriptive statistics on the asthma exacerbations that contributed to the analysis. Of the 13,484 exacerbations, 56% were recorded

Discussion

In this analysis of over 13,000 clinical encounters among children living in the metropolitan Philadelphia region of the United States, we observed a modest association between heavy precipitation and asthma exacerbation. There was evidence of seasonal effects; results were restricted to the summer months and strongest in August and June.

These results are somewhat consistent with data from Maryland, where heavy precipitation events were associated with higher risk of hospitalization for asthma (

Conclusions

Results from this analysis suggest that heavy precipitation events are associated with a modest increase in odds of childhood asthma exacerbation, especially in the summer, and when grass pollen concentrations are high. Further investigation of the mechanisms that underlie these relationships, considering different asthma phenotypes, and in other geographic areas, is needed to confirm and extend this research. Overall, this research contributes to evidence that climate change has impacts on

Funding

This study is part of the Pediatric Big Health Data initiative funded by the State of Pennsylvania and led by the Children's Hospital of Philadelphia, University of Pennsylvania, and the Urban Health Collaborative at Drexel University. We would like to thank the investigators of the Pediatric Big Health Data initiative for their contributions. These individuals include: Christopher B. Forrest, MD, PhD; L. Charles Bailey, MD, PhD; Shweta P. Chavan, MSEE; Rahul A. Darwar, MPH; Jillian Benedetti,

CRediT authorship contribution statement

Leah H. Schinasi: Conceptualization, Methodology, Writing - original draft, Software. Chén C. Kenyon: Conceptualization, Writing - review & editing. Kari Moore: Data curation, Writing - review & editing. Steve Melly: Data curation, Writing - review & editing. Yuzhe Zhao: Data curation, Writing - review & editing, Software. Rebecca Hubbard: Methodology, Writing - review & editing. Mitch Maltenfort: Data curation, Writing - review & editing. A.V. Diez Roux: Funding acquisition, Writing - review &

Declaration of competing interest

The authors have no conflicts of interest to disclose.

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