Short-Term Association between Ambient Temperature and Mental Disorders Hospitalization in an Asian Subtropical City: A Time-Series Study

摘要

Background With the increasing evidence of climate change, human health impact associated with rising global temperature has received more attention. Studies from higher latitudes, with cooler climates, have reported positive temperature-mental disorders association but the association from lower latitudes with warmer climates is still unclear. This study showed the short-term temperature-mental disorders association in a subtropical city located below the Tropic of Cancer with an annual mean temperature over 21℃. Methods Daily mental disorders admissions to public hospitals in Hong Kong during 2002-2011 were regressed on daily mean temperature using distributed lagged nonlinear models with relative humidity, air pollutants, seasonal trend, long term trend, day-of-week and holiday adjusted in the models. Sub-group analyses by disease classes, gender and age-group were conducted. Results A total of 44 600 admissions were included in this study. Temperature was linearly and positively associated with overall mental disorder hospitalizations. The cumulative relative risk of admissions at 28℃ vs. 19.4℃ (interquartile range, lag 0-2 days) was 1.09 (95% confidence interval 1.03,1.15). The effect of rising temperature above a threshold of 19℃ was the strongest among the elderly > 75 years old. In subgroup analyses by disease classes, episodic mood disorders and transient mental disorders due to conditions classified elsewhere showed strong positive associations with temperature. Conclusions The results of this study agreed with most of those from prior studies that high temperature was associated with a higher risk of mental disorders and the effects were more prominent among older people. The global number of heat-related mental disorder events may grow with the dual effect of global warming and aging population. Health policies should be drafted to address these issues.