Analysis on the ratio of emergency department visits by elderly and non-elderly patients based on disease and particulate matter concentration in South Korea: a multicenter cross-sectional observational study

Abstract

Objective: Many previous studies have reported relationships between particulate matter < 10 μm (PM10) and asthma in emergency department (ED) settings, but few have examined its effect on cerebrovascular diseases. We evaluate the “Lag effect” between PM10 and asthma, chronic obstructive pulmonary disease (COPD), myocardial infarction (MI), and ischemic and hemorrhagic stroke among patients that visited an ED. Methods: This study was retrospectively conducted on 96,077 patients that visited one of the 137 EDs in Seoul, Incheon, and Gyeonggi Province in South Korea in 2017. Medical information and 10th revision International Classification of Disease codes were obtained from the National Emergency Department Information System and PM10 levels from AirKorea. We used Poisson regression analysis to evaluate the lag effects of PM10 on diseases of interest. “Lag day 0” was defined as the day when PM10 > 80 μg/m3, and the PM10 values on the 5 following days were recorded. To assess the cumulative effects of PM10, we calculated relative risk (RR) by analyzing the cumulative effects over 6 days (lag days 0 to 5). Results: Asthma, COPD, and ischemic stroke patients (< 65 years old) showed a positive correlation between PM10 (asthma on lag day 5: RR, 2.587; 95% confidence interval [CI], 2.001-3.344; COPD on lag day 4: RR, 3.727; 95% CI, 2.988-4.650; and ischemic stroke on lag day 4: RR, 1.573; 95% CI, 1.168-2.118). MI in those≥65 showed the highest RR on lag day 1 (RR, 1.471; 95% CI, 1.042-2.077). Hemorrhagic stroke was not found to be significantly correlated with PM10 in either age group. Conclusion: An increase in PM10 is associated with ED visits by patients<65 years old with asthma, COPD, or ischemic stroke, and with MI for those≥65 years.