The Pattern of Environmental Allergic Sensitization and Association with Pollution in the Kaiser Permanente Southern California Population

Abstract

RATIONALE: There are multiple known triggers for asthma exacerbations. Anecdotally, parents often claim temperature changes as the single trigger in their children. There are few studies supporting or refuting this association however. The objective of this study was to examine if temperature change is temporally associated with an increase in asthma exacerbations. METHODS: We performed a retrospective review of pediatric (2-17 years) emergency department visits and hospitalizations secondary to asthma exacerbations for the year 2012 at a single pediatric hospital. A quasi-Poisson regression combined with a distributed lag nonlinear model (DLNM) was applied to evaluate the association between inter-day temperature change and visit frequency. The analyses adjusted for daily pollutant variables, other weather variables, and temporal factors to control seasonal and long-term patterns. RESULTS: 2728 encounters were examined with an average of 7.5 daily visits. There is a general non-significant trend that greater negative interday temperature change is associated with a greater number of hospital visits, with its effect persisting for 7 days. A one-day 20 degree drop was associated with a relative risk (RR) of 1.24 (95% CI: 0.92 to 1.66). The 7day cumulative RR resulting from a -108F and -208F change are 1.24 (95% CI: 0.74 to 2.10) and 2.80 (95% CI: 0.54 to 14.50), respectively. CONCLUSIONS: Although not statistically significant, there is a strong trend suggesting a drop in temperature leads to increased hospital visits for asthma. Further studies with inclusion of pollen data and data from multiple years may help improve the validity of this association.