Timely accessibility to healthcare resources and heatwave-related mortality in 7 major cities of South Korea: a two-stage approach with principal component analysis

Jungsil Lee; Jieun Min; Whanhee Lee; Kyongmin Sun; Won Chul Cha; Chaerin Park; Cinoo Kang; Juyeon Yang; Dohoon Kwon; Youngrin Kwag; Jongmin Oh; Jae-Hong Ryoo; Eunhee Ha

doi:10.1016/j.lanwpc.2024.101022

Timely accessibility to healthcare resources and heatwave-related mortality in 7 major cities of South Korea: a two-stage approach with principal component analysis

Lancet Reg Health West Pac. 2024 Feb 5:45:101022. doi: 10.1016/j.lanwpc.2024.101022. eCollection 2024 Apr.

Authors

Jungsil Lee^{1

2}, Jieun Min^{1

3}, Whanhee Lee⁴, Kyongmin Sun⁵, Won Chul Cha^{6

7}, Chaerin Park⁸, Cinoo Kang⁸, Juyeon Yang⁹, Dohoon Kwon⁸, Youngrin Kwag¹, Jongmin Oh^{1

2

10}, Jae-Hong Ryoo¹¹, Eunhee Ha^{1

2

3}

Affiliations

¹ Department of Environmental Medicine, College of Medicine, Ewha Womans University, Seoul, Republic of Korea.
² Institute of Ewha-SCL for Environmental Health (IESEH), Ewha Womans University College of Medicine, Seoul, Republic of Korea.
³ Graduate Program in System Health Science and Engineering, College of Medicine, Ewha Womans University, Seoul, Republic of Korea.
⁴ School of Biomedical Convergence Engineering, College of Information and Biomedical Engineering, Pusan National University, Yangsan, Republic of Korea.
⁵ Department of Emergency Medicine, Ewha Womans University Seoul Hospital, Seoul, Republic of Korea.
⁶ Department of Emergency Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
⁷ Department of Digital Health, Samsung Advanced Institute for Health Science & Technology (SAIHST), Sungkyunkwan University, Seoul, Republic of Korea.
⁸ Department of Public Health Sciences, Graduate School of Public Health, Seoul National University, Seoul, Republic of Korea.
⁹ Biostatistics Collaboration Unit, Yonsei University College of Medicine, Seoul, Republic of Korea.
¹⁰ Department of Human Systems Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea.
¹¹ Department of Occupational and Environmental Medicine, School of Medicine, Kyung Hee University, Seoul, Republic of Korea.

Abstract

Background: Due to the ongoing effects of climate change, the incidence of heatwave-related mortality is rising globally. Improved allocation and utilization of healthcare resources could help alleviate this issue. This study aimed to identify healthcare resource factors associated with heatwave-related mortality in seven major cities of South Korea.

Methods: We analyzed daily time-series data on mean temperature and all-cause mortality from 2011 to 2019. Using principal component analysis (PCA), we clustered district-level healthcare resource indicators into three principal components (PCs). To estimate district-specific heatwave-mortality risk, we used a distributed lag model with a quasi-Poisson distribution. Furthermore, a meta-regression was performed to examine the association between healthcare resources and heatwave-mortality risk.

Findings: A total of 310,363 deaths were analyzed in 74 districts. The lag-cumulative heatwave-related mortality (RRs) ranged from 1.12 (95% confidence interval [CI]: 1.07, 1.17) to 1.21 (95% CI 1.05, 1.38), depending on the definitions used for heatwaves. Of the three PCs for healthcare resources (PC1: pre-hospital emergency medical service, PC2: hospital resources, PC3: timely access), timely access was associated with reduced risk of heatwave-related mortality, particularly among the elderly. Specifically, timely access to any emergency room (ER) exhibited the strongest association with lower heatwave-related mortality.

Interpretation: Our findings suggest that timely access to any ER is more effective in reducing heatwave-related mortality risk than access to higher-level healthcare facilities, especially among the elderly. Therefore, healthcare resource factors and ER accessibility should be prioritized when identifying vulnerable populations for heatwaves, along with known individual and socio-demographic factors.

Funding: This work was supported by the Research Program funded by the Korea Disease Control and Prevention Agency (2022-12-303), the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2022R1A2C2092353) and the MD-PhD/Medical Scientist Training Program through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea.

Keywords: Accessibility; Climate change; Emergency care; Extreme temperatures; Healthcare service; Heatwaves; Mortality; Principal component analysis; Resources.