Abstract
BACKGROUND AND AIM: The effect of particulate matter with a size of 2.5 micrometer (PM2.5) in diameter on asthma has been well-documented in previous studies. Ambient PM2.5 exposure exacerbates the risk of developing asthma. However, asthma has a wide spectrum of diagnostic classification. Several patients can be diagnosed with asthma but may not need medications, others, on the other hand, may require long-term treatment. To the best of our knowledge, there is inconclusive evidence whether diagnostic classifications confer differential PM2.5-related health effects. METHODS: We utilized a health insurance claim database with the detailed medical information of 21 Japanese cities from 2013-2017 to elucidate these associations. Specifically, asthma clinic visits were classified into seven (7) diagnostic classifications, namely: 1) illness only, 2) medication only, 3) treatment only, 4) illness and medication, 5) medication and treatment, 6) medication and illness, and 7) illness, medication and treatment. Daily clinic visits (n = 4,983,521) were analyzed using a generalized additive mixed model after adjusting for several covariates (temperature, relative humidity, temporal variables, etc.) as well as city-random effects, sourced out from literature. RESULTS:Exposure to PM2.5 resulted to a statistically significant increase in the risk, regardless of diagnostic classification. While the magnitude of effects did not vary substantially between diagnostic classification, we generally observe an increasing risk with more complex diagnostic classification. For example, (Classification 1) illness only had a percent change in the risk by 0.933% [95% Confidence Interval (CI): 0.856, 1.01%], it increased when accompanied with medication (Classification 4) (1.01%; 95% CI: 0.901, 1.119%), and was magnified when it further included treatment (Classification 7) (1.058%; 95%CI: 0.916, 1.201%). CONCLUSIONS:In this study, though we did not find any compelling evidence on the differential effect of diagnostic classification on asthma visit-PM2.5 associations, it is worthy to further investigate the potential trend of increasing risk with increasingly complex diagnostic classification. KEYWORDS: asthma, diagnostic classification, particulate matter, clinic visit
Published Version
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