Chenxiang Long ¹ Guo Shengyu ² Ping Tian ^3* Yingying Sun ^4*

• ¹ College of Biology and Engineering, Guizhou Medical University, Guiyang, Guizhou Province, China
• ² Department of Economics and Management, Changsha University, Changsha, Hunan, China
• ³ School of Public Health, Guizhou Medical University, Guiyang, Guizhou Province, China
• ⁴ Department of Emergency Medicine, Tianjin Medical University General Hospital, Tianjin, China

Background: While temperature extremes have been shown to be associated with increased risk of hospital admissions, evidence on the impact on length of hospital stay, which may capture the lingering effect of temperature extremes, is scarce. Objectives: We aimed to evaluate the association between daily variation in ambient temperature and daily variation in daily total length of stay (daily TLOS), which was a composite measure of daily count of hospital admissions and their corresponding length of hospital stay, among cardiopulmonary patients. We further quantified the burden of TLOS attributable to non-optimal temperature among Hong Kong’s elderly population. Methods: We used a generalized linear regression with a distributed lag nonlinear model to estimate the association between ambient temperature and daily TLOS using 13-year time-series data on daily temperature and hospital admissions for cardiopulmonary disease via accident and emergency departments from 1998 to 2010 among Hong Kong elderly population. We quantified temperature attributable risk of TLOS by calculating temperature-related days of hospital stay and attributable fraction (AF). Results: We recorded a total of 4,095,722 days of hospital stay for cardiovascular patients and 4,492,697 days for respiratory patients. We found both cold and heat were associated with increased TLOS for cardiopulmonary disease. The temperature-related AF was 11.5% (95% empirical CI: 5.3%-17.2%) for cardiovascular disease, equalling 36,174 (95% empirical CI: 15,286-57,018) days of increase annually, and 10.7% (95% empirical CI: 7.1%- 13.9%) for respiratory disease, equalling 36,897 (95% empirical CI: 24,949-49,024) days annually. Conclusions: Days of extreme temperature were associated with increased TLOS for cardiopulmonary patients in the Hong Kong’s elderly population. These findings allow hospitals to prepare in advance for days with extreme temperatures, taking specific measures in terms of human resources, material resources and medical resources. In addition, these findings may provide scientific evidence for public health policies and hospital planning and management.