Air pollution and mortality in patients with chronic obstructive pulmonary disease: a cohort study in South Korea

Suna Kang; Yun Soo Hong; Jihwan Park; Danbee Kang; Hyunsoo Kim; Jin Lee; Woojin Kim; Sung-Won Kang; Eliseo Guallar; Juhee Cho; Hye Yun Park

doi:10.1177/20406223231176175

Air pollution and mortality in patients with chronic obstructive pulmonary disease: a cohort study in South Korea

Ther Adv Chronic Dis. 2023 Jun 6:14:20406223231176175. doi: 10.1177/20406223231176175. eCollection 2023.

Authors

Suna Kang^{1

2}, Yun Soo Hong³, Jihwan Park³, Danbee Kang^{2

4}, Hyunsoo Kim^{4

5}, Jin Lee^{2

4}, Woojin Kim⁶, Sung-Won Kang⁷, Eliseo Guallar³, Juhee Cho^{8

3

4

5}, Hye Yun Park^{2

9}

Affiliations

¹ Korea Environment Institute, Sicheong-daero, Sejong, South Korea.
² Department of Clinical Research Design and Evaluation, SAIHST, Sungkyunkwan University, Seoul, South Korea.
³ Departments of Epidemiology and Medicine, and Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
⁴ Center for Clinical Epidemiology, Samsung Medical Center, Seoul, South Korea.
⁵ Department of Digital Health, SAIHST, Sungkyunkwan University, Seoul, South Korea.
⁶ Department of Internal Medicine and Environmental Health Center, Kangwon National University Hospital, Kangwon National University School of Medicine, Chuncheon, South Korea.
⁷ Korea Environment Institute, Sejong, South Korea.
⁸ Department of Clinical Research Design and Evaluation, SAIHST, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul 06351, South Korea.
⁹ Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, South Korea.

Abstract

Background: Evidence on whether long-term exposure to air pollution increases the mortality risk in patients with chronic obstructive pulmonary disease (COPD) is limited.

Objectives: We aimed to investigate the associations of long-term exposure to particulate matter with diameter <10 µm (PM₁₀) and nitrogen dioxide (NO₂) with overall and disease-specific mortality in COPD patients.

Design: We conducted a nationwide retrospective cohort study of 121,423 adults ⩾40 years diagnosed with COPD during 1 January to 31 December 2009.

Methods: Exposure to PM₁₀ and NO₂ was estimated for residential location using the ordinary kriging method. We estimated the risk of overall mortality associated with 1-, 3-, and 5-years average concentrations of PM₁₀ and NO₂ using Cox proportional hazards models and disease-specific mortality using the Fine and Gray method adjusted for age, sex, income, body mass index, smoking, comorbidities, and exacerbation history.

Results: The adjusted hazard ratios (HRs) for overall mortality associated with a 10 µg/m³ increase in 1-year PM₁₀ and NO₂ exposures were 1.004 [95% confidence interval (CI) = 0.985, 1.023] and 0.993 (95% CI = 0.984, 1.002), respectively. The results were similar for 3- and 5-year exposures. For a 10-µg/m³ increase in 1-year PM₁₀ and NO₂ exposures, the adjusted HRs for chronic lower airway disease mortality were 1.068 (95% CI = 1.024, 1.113) and 1.029 (95% CI = 1.009, 1.050), respectively. In stratified analyses, exposures to PM₁₀ and NO₂ were associated with overall mortality in patients who were underweight and had a history of severe exacerbation.

Conclusion: In this large population-based study of patients with COPD, long-term PM₁₀ and NO₂ exposures were not associated with overall mortality but were associated with chronic lower airway disease mortality. PM₁₀ and NO₂ exposures were both associated with an increased risk of overall mortality, and with overall mortality in underweight individuals and those with a history of severe exacerbation.

Keywords: COPD; air pollution; mortality; nitrogen dioxide; particulate matter.