Impact of Heat Wave Definitions on the Added Effect of Heat Waves on Cardiovascular Mortality in Beijing, China

Abstract

Heat waves are associated with increased mortality, however, few studies have examined the added effect of heat waves. Moreover, there is limited evidence for the influence of different heat wave definitions (HWs) on cardiovascular mortality in Beijing, the capital of China. The aim of this study was to find the best HW definitions for cardiovascular mortality, and we examined the effect modification by an individual characteristic on cardiovascular mortality in Beijing, a typical northern city in China. We applied a Poisson generalized additive approach to estimate the differences in cardiovascular mortality during heat waves (using 12 HWs) compared with non-heat-wave days in Beijing from 2006 to 2009. We also validated the model fit by checking the residuals to ensure that the autocorrelation was successfully removed. In addition, the effect modifications by individual characteristics were explored in different HWs. Our results showed that the associations between heat waves and cardiovascular mortality differed from different HWs. HWs using the 93th percentile of the daily average temperature (27.7 °C) and a duration ≥5 days had the greatest risk, with an increase of 18% (95% confidence interval (CI): 6%, 31%) in the overall population, 24% (95% CI: 10%, 39%) in an older group (ages ≥65 years), and 22% (95% CI: 3%, 44%) in a female group. The added effect of heat waves was apparent after 5 consecutive heat wave days for the overall population and the older group. Females and the elderly were at higher risk than males and younger subjects (ages <65 years). Our findings suggest that heat wave definitions play a significant role in the relationship between heat wave and cardiovascular mortality. Using a suitable definition may have implications for designing local heat early warning systems and protecting the susceptible populations during heat waves.

Health Impact of Climate Change in Older People: An Integrative Review and Implications for Nursing

“…Males were at a greater risk to die from typhoons (Myung & Jang, 2011) and hospitalized for ischemic heart disease (Chau et al, 2014). Other studies documented that females are at a higher risk for heatrelated deaths (Dong et al, 2016;Nitschke et al, 2013;Yin & Wang, 2017). This is in contrast to an epidemiologic study in China reporting higher risk in males (Cheng et al, 2014).…”

“…In general, increasing temperature is associated with an increase in mortality (Cheng et al, 2014;Dong, Zeng, Ma, Li, & Pan, 2016;Son, Lee, Anderson, & Bell, 2012;Yin & Wang, 2017). Mortality due to cardiovascular diseases was reported to increase by 24% during periods of temperatures above 27.7oC lasting for more than 5 days (Dong et al, 2016), rising to a 94% increase on the 10th day of temperatures higher than 33oC (Yin & Wang, 2017). A 1.9oC increase in maximum daily temperature corresponds to a 3% increase in cardiovascular mortality (Cheng et al, 2014).…”

“…Heat as a stressor was measured differently: either as temperature variability (Harlan et al, 2014;Ren et al, 2011), temperature-humidity index (Dong et al, 2016;Isaksen et al, 2014), or the presence of a heat wave (Bobb et al, 2014;Son et al, 2012). Typhoons and flooding were more straightforward, measured by the presence of a storm or flood (Bei et al, 2013;Ching et al, 2015).…”

Changes of concurrent drought and heat extremes in the arid and semi‐arid regions of China during 1961–2014

“…The HW in the summer of 2010 in Russia caused around 55,000 deaths and led to economic damage of 15 billion US dollars (Barriopedro et al, 2011;Rahmstorf and Coumou, 2011). The HWs in 1998 and 2003 elevated the mortality risk in Beijing (Dong et al, 2016;Yin and Wang, 2017).…”

Is Sensible Heat Flux Useful for the Assessment of Thermal Vulnerability in Seoul (Korea)?

“…Summers in Seoul are characterised by heavy rain (precipitation: 892.1 mm), whereas winters are relatively dry (precipitation: 67.3 mm). Since heatwaves vary in duration, intensity, or temperature depending on where they occur, there are naturally various definitions of heatwaves [72,73]. Therefore, studies that set the threshold through health indicators have recently been performed.…”