Effects of diurnal temperature range on mortality in Hefei city, China

Impact of non optimal ambient temperature and temperature variation on the mortality of cardiovascular diseases: a research in Wuhu, China

Given the backdrop of global climate change, future temperatures are anticipated to exhibit increased variability and extremity, amplifying health risks and the burden of diseases, a matter of heightened concern. The aim of this research was to evaluate the mortality risk associated with cardiovascular diseases (CVD) due to suboptimal temperatures (daily mean temperature) and temperature variations (diurnal temperature range). Daily data spanning from 2014 to 2020 in Wuhu City were gathered, encompassing meteorological factors, environmental pollutants, and cardiovascular disease mortality information, involving 64,758 CVD deaths. Time-series analyses were conducted utilizing generalized additive models (GAM) and distributed lag nonlinear models (DLNM). Burden analysis was executed to estimate the percentage and count of daily CVD deaths linked to daily mean temperature (DMT) and diurnal temperature range (DTR). Lastly, a sensitivity analysis was conducted to assess the robustness of the model. A horizontal S-shaped relationship exists between DMT and CVD mortality rate, where both high and low temperatures exhibit adverse effects, with high temperatures demonstrating a more pronounced impact than low temperatures. An inverted J-shaped relationship exists between DTR and mortality, wherein extreme DTR elevates the risk of CVD mortality. Variations in exposure responses occur among populations with diverse characteristics. The main cause of death burden is moderately high temperature rather than extreme temperature. Importantly, non-extreme temperatures account for the majority of cardiovascular disease deaths, potentially exerting serious adverse effects on local public health.

Mortality and diurnal temperature range in Virginia

The relationship between diurnal temperature range (DTR) and daily mortality from 2005 to 2020 is examined for seven large metropolitan areas in Virginia using distributed lag non-linear models that control for temperature and humidity. The relative risk of mortality increases for very high DTR, and there is a short lag effect of several days. High risk DTR days are rare, typically occurring less than 1% of the time at most locations. These days primarily occur in spring and are characterized by high pressure and low humidity that allow overnight temperatures to drop substantially. High DTR days are often associated with elevated respiratory and cardiovascular mortality and tend to impact the elderly. The similarity between the mortality response to high DTR and that of high temperatures alone, coupled with the lack of clear physiological underpinnings, challenges the notion that these responses are independent. The prevalent spring peak in dangerous DTR days suggests that lack of acclimatization to hot and humid conditions may impose strain on the cardiovascular and respiratory systems.

The effects of temperature variability on ischemic heart disease mortality in Hangzhou, China

Ischemic heart disease (IHD) is a leading cause of death in cardiovascular patients. In China, the disease burden of IHD deaths has significantly increased. One of the main influencing factors of IHD is changing climates, and temperature and diurnal temperature range (DTR) are important indicators of climate change. In this study, we aimed to assess the associations of temperature variability on IHD mortality in a fast developing city Hangzhou,China. We obtained daily IHD mortality data and meteorological data from mortality surveillance system from 2014 to 2016. Quasi-Poisson generalized linear regression with a distributed lag non-linear model (DLNM) was applied to estimate the associations between temperature variability and IHD deaths. Potential confounders were controlled in the analysis, including relative humidity, day of the week, public holidays, and long-term trends. A total of 7423 IHD mortality data were included in this study. A J-shaped pattern of DTR and a reversely J-shaped pattern of temperature for IHD mortality were observed. Risk estimates showed that the relative risks (RRs) of IHD mortality with extreme high DTR at lag 0-7 days were 1.309 (95% CI: 0.985, 1.740) while RRs of IHD mortality with extreme low DTR at lag 0-2 days were 1.234 (95% CI: 1.043, 1.460). For extreme hot temperature, the highest RRs at lag 0-2 days were 1.559 (95% CI: 1.250, 1.943); for extremely cold temperatures, the RRs increased from 1.049 (95% CI: 0.930, 1.183) to 2.089 (95% CI: 1.854, 2.352). In Hangzhou city, short-term exposure to extreme temperature was associated with mortality for IHD. These findings have implications for policy decision-making and targeted interventions.

The relationship of short-term exposure to meteorological factors on diabetes mellitus mortality risk in Hefei, China: a time series analysis

OBJECTIVES

The study aims to explore whether short-term exposure to meteorological factors has a potential association with the risk of diabetes mellitus (DM) mortality.

METHODS

During the period 2015-2018, we collected daily data on meteorological factors and deaths of diabetic patients in Hefei. A total of 1101 diabetic deaths were recorded. We used structural equation modeling to initially explore the relationships among air pollutants, meteorological variables, and mortality, and generalized additive modeling (GAM) and distributional lag nonlinear modeling (DLNM) to explore the relationship between meteorological factors and the mortality risk of DM patients. We also stratified by age and gender. The mortality risk in diabetic patients was expressed by relative risks (RR) and 95% confidence intervals (CI) for both single and cumulative days.

RESULTS

Single-day lagged results showed a high relative humidity (RH) (75th percentile, 83.71%), a fairly high average temperature (T mean) (95th percentile, 30.32 °C), and an extremely low diurnal temperature range (DTR) (5th percentile, 3.13 °C) were positively related to the mortality risk of DM. Stratified results showed that high and very high levels of T mean were significantly positively linked to the mortality risk of DM among females and the elderly, while very high levels of DTR were linked to the mortality risk in men and younger populations.

CONCLUSION

In conclusion, this study found that short-duration exposure to quite high T mean, high RH, and very low DTR were significantly positively related to the mortality risk of DM patients. For women and older individuals, exposure to high and very high T mean environments should be minimized. Men and young adults should be aware of daily temperature changes.

Differences in cardiovascular disease mortality between northern and southern China under exposure to different temperatures: a systematic review

Background

Due to differences in climate and other environmental factors, exposure to different temperatures in China has different effects on the relative risk (RR) of cardiovascular disease (CVD) mortality. It is therefore important to compare the effects of exposure to different temperatures on CVD mortality in different regions of China.

Methods

To compare these effects, we performed a meta-analysis of 21 studies identified by a search of the Web of Science and China National Knowledge Infrastructure databases from January 1, 2014 to January 1, 2024. We performed the Cochran Q test and I 2 statistics test to evaluate heterogeneity and Egger's test to evaluate publication bias.

Results

The pooled estimated size of the relationship between exposure to different temperatures and CVD mortality was 1.60 (95% confidence interval [CI]: [1.42-1.80]) for the extreme cold, 1.17 (95% CI [1.10-1.25]) for the extreme heat, and 1.16 (95% CI [1.10-1.24]) for extremely high diurnal temperature range (DTR). The Egger's test showed potential publication bias in studies analyzing both the extreme cold and the extreme heat.

Discussion

Extreme cold, extreme heat, and extremely high DTR are associated with an increase in CVD mortality in China, with extreme cold having the most significant effect. Residents of northern regions are more susceptible to high temperatures, while residents of southern regions are more sensitive to low temperatures.

Immediate and delayed effects of environmental temperature on schizophrenia admissions in Liuzhou, China, 2013-2020: a time series analysis

This study aimed to investigate the associations between environmental temperature and schizophrenia admissions in Liuzhou, China. A Poisson generalized linear model combined with a distributed lag nonlinear model was used to analyze the effects of daily mean temperature on schizophrenia admissions from 2013 to 2020 in Liuzhou. Additionally, subgroup analyses were conducted to investigate possible modifications stratified by gender, marital status, and age. In this study, 10,420 schizophrenia admissions were included. The relative risks of schizophrenia admissions increased as the temperature rose, and the lag effects of high temperature on schizophrenia admissions were observed when the daily mean temperature reached 21.65°C. The largest single effect was observed at lag0, while the largest cumulative effect was observed at lag6. The single effects of high temperatures on schizophrenia admissions were statistically significant in both males and females, but the cumulative effects were statistically significant only in males, with the greatest effect at lag0-7. The single effect of high temperatures on admissions for unmarried schizophrenics was greatest at lag5, while the maximum cumulative effect for unmarried schizophrenia was observed at lag0-7. The single effects of high temperatures on schizophrenia admissions were observed in those aged 0-20, 21-40, and 41-60. The cumulative effects for schizophrenics aged 21-40 were observed from lag0-3 to lag0-7, with the maximum effect at lag0-7. In conclusion, the risk of schizophrenia admissions increased as the environmental temperature increased. The schizophrenics who were unmarried appeared to be more vulnerable to the single and cumulative effects of high temperature.

The impact of short-term exposure to meteorological factors on the risk of death from hypertension and its major complications: a time series analysis based on Hefei, China

OBJECTIVES

This study aimed to reveal the short-term impact of meteorological factors on the mortality risk in hypertensive patients, providing a scientific foundation for formulating pertinent prevention and control policies.

METHODS

In this research, meteorological factor data and daily death data of hypertensive patients in Hefei City from 2015 to 2018 were integrated. Time series analysis was performed using distributed lag nonlinear model (DLNM) and generalized additive model (GAM). Furthermore, we conducted stratified analysis based on gender and age. Relative risk (RR) combined with 95% confidence interval (95% CI) was used to represent the mortality risk of single day and cumulative day in hypertensive patients.

RESULTS

Single-day lag results indicated that high daily mean temperature (T mean) (75th percentile, 24.9 °C) and low diurnal temperature range (DTR) (25th percentile, 4.20 °C) levels were identified as risk factors for death in hypertensive patients (maximum effective RR values were 1.144 and 1.122, respectively). Extremely high levels of relative humidity (RH) (95th percentile, 94.29%) reduced the risk of death (RR value was 0.893). The stratified results showed that the elderly and female populations are more susceptible to low DTR levels, whereas extremely high levels of RH have a more significant protective effect on both populations.

CONCLUSION

Overall, we found that exposure to low DTR and high T mean environments increases the risk of death for hypertensive patients, while exposure to extremely high RH environments significantly reduces the risk of death for hypertensive patients. These findings contribute valuable insights for shaping targeted prevention and control strategies.

Short-term impact of diurnal temperature range on cardiovascular diseases mortality in residents in northeast China

It has been reported that cardiovascular disease (CVD) has become one of the major threats to global public health and is associated with climate change. Several previous studies have shown the influence of ambient temperature on CVD, but lack some evidence for the short-term effect of diurnal temperature range (DTR) on CVD mortality in northeast China. This is the first study to assess the correlation between DTR and CVD mortality in Hulunbuir located in northeast China. Daily CVD mortality data and meteorological data were collected from 2014 to 2020. A quasi-Poisson generalized linear regression with a distributed lag non-linear model (DLNM) was applied to exploring the short-term impact of DTR on CVD mortality. Stratified analyses by gender, age, and season were conducted and the short-term impacts of extremely high DTR on CVD mortality were investigated. In this study, a total of 21,067 CVD mortality cases were recorded in Hulunbuir, China from 2014 to 2020. Compared to the reference value (11.20 [Formula: see text]C, 50[Formula: see text] percentile), a "U-shaped" non-linear relationship between DTR and CVD mortality was observed, and extremely high DTR increased the risk of CVD mortality. The short-term effect of extremely high DTR occurred immediately and lasted up to 6 days. In addition, the male and the age [Formula: see text] 65 groups were more likely to be affected by extremely high DTR compared with the female and the age < 65 groups, respectively. The results also showed that extremely high DTR in cold season had a more adverse effect on CVD mortality than warm season. This study suggests that extremely high DTR for cold season should be paid enough attention to for residents in northeast China. The male and the age [Formula: see text] 65 groups were more vulnerable to the impacts of DTR. The study results may provide some suggestions for decision-making by local public health authorities to avoid the adverse impacts of high DTR, and improve the health of residents, especially vulnerable groups in cold season.

The association of ambient temperature variability with blood pressure in southern China

OBJECTIVES

Numerous studies have shown a positive relationship between temperature variability and mortality, but few studies have investigated the effect of temperature variability on blood pressure (BP). We aimed to estimate the effect of temperature variability on BP in Guangdong Province, southern China.

METHODS

Data on meteorological factors were obtained from the Guangdong Meteorological Center, and BP was collected from a series of cross-sectional surveys conducted in Guangdong Province, China, from 2004 to 2015. There were 38 088 participants aged 18 years and over. A generalized additive model was used to estimate the association between temperature variability and BP after adjusting for confounding variables.

RESULTS

Our study found a significant positive association between temperature variability and SBP, and this effect increased with the increment of exposure days in total population. The highest estimate was for temperature variability at 7 days lag (TV 0-7 ) with a 0.497 (95% confidence interval, 0.335-0.660) mmHg rise of SBP for each 1°C increase of TV 0-7 . The effects of TV 0-1 and TV 0-2 on SBP were higher for hypertensives than that for normotensives, and in warm season higher than that in cold season. However, we did not observe statistical significance between temperature variability and DBP.

CONCLUSIONS

There was a positive association between temperature variability and SBP in Guangdong Province, which should be considered in clinical management and epidemiological survey of hypertension.

The role of meteorological factors in suicide mortality in Wuhu, a humid city along the Yangtze River in Eastern China

As the climate continues to change, suicide is becoming more frequent. In this study, absolute humidity (AH) was included for the first time and Wuhu, a typical subtropical city along the Yangtze River, was taken as the research object to explore the impact of suicide death risk on meteorological factors. The daily meteorological factors and suicide mortality data of Wuhu city from 2014 to 2020 were collected. Guided by structural equation model (SEM), a time series analysis method combining distributed lag nonlinear model (DLNM) and generalized additive model (GAM) was adopted. To investigate the correlation among different populations, we stratified age and gender at different meteorological levels. A total of 1259 suicide deaths were collected in Wuhu. The results indicated that exceedingly low and low levels of AH short-term exposure increased suicide mortality, with the maximum effect occurring at lag 14 for both levels of exposure, when the relative risk (RR) was 1.131 (95% CI: 1.030, 1.242) and 1.065 (95% CI: 1.006, 1.127), respectively. Exposure to exceedingly high and exceedingly low levels of temperature mean (T mean) also increased suicide mortality, with maximum RR values of 1.132 (lag 14, 95% CI: 1.015, 1.263) and 1.203 (lag 0, 95% CI: 1.079, 1.340), sequentially. As for diurnal temperature range (DTR), low-level exposure decreased the risk of suicide, while high-level exposure increased this risk, with RR values of 0.955 (lag 0, 95% CI: 0.920, 0.991, minimum) and 1.060 (lag 0, 95% CI: 1.018, 1.104, maximum), sequentially. Stratified analysis showed that AH and DTR increased the suicide death risk in male and elderly people, while the risk effect of T mean have no effect on young people only. In summary, male and elderly people appear to be more vulnerable to adverse weather effects.

Health effect of temperature change on respiratory diseases in opposite phase in semi-arid region

The impact of temperature variation on health has attracted increasing attention under global climate change. A distributed lag non-linear model (DLNM) was performed to estimate the risk of two indicators of temperature change (diurnal temperature range (DTR) and temperature change between neighboring days (TCN)) on respiratory hospital visits in Lanzhou, a semi-arid climate city in western China from 2012 to 2018. The whole year is divided into two different temperature change periods according to the TCN of each solar term. The results showed that extreme high DTR can apparently enlarge respiratory risk, and it indicated strong cumulative relative risk (RR) in the temperature drop period. Extreme low TCN had strong adverse effects on respiratory diseases especially in temperature rise period, with the greatest RR of 1.068 (95% CI 1.004, 1.136). The effect of extreme high TCN was more obvious in temperature drop period, with a RR of 1.082 (95% CI 1.021, 1.148) at lag 7. Females were more affected by extreme temperature changes. Young people were more vulnerable to DTR, while TCN has a greater impact on the elderly.

The effects of temperature variability on mortality in patients with chronic obstructive pulmonary disease: a time-series analysis in Hangzhou, China

Chronic obstructive pulmonary disease (COPD) is a leading cause of death in people aged over 60 years old. Research has been reported that ambient temperature and diurnal temperature range (DTR), as representative indices of temperature variability, are contributors to the development and exacerbation of COPD. However, few studies are available in Chinese population. In this study, we aimed to assess the associations of temperature variability on COPD mortality in a fast developing city in China. Using the mortality surveillance system, we obtained a total of 7,863 deaths attributed to COPD from 2014 to 2016. Quasi-Poisson generalized linear regression with distributed lag non-linear model was applied to explore the associations between temperature variability and COPD deaths, after controlling for the potential confounders, including relative humidity, day of week, public holiday, and long-term trend. A J-shaped association of DTR and a reversely J-shaped association of temperature for COPD mortality were observed. Risk estimates showed that the relative risks (RRs) of COPD mortality with extreme high DTR at lag 0 and 0-7 days were 1.045 (95% CI: 0.949-1.151) and 1.460 (95% CI: 1.118-1.908), and the extreme high temperature at lag 0 and 0-7 days were 1.090 (95% CI: 0.945-1.256) and 1.352 (95% CI: 1.163-1.572). Our findings suggest that short-term exposure to extreme temperature was associated with mortality for COPD in Hangzhou. The evidence has implications for policy decision-making and targeted interventions.

Impact of diurnal temperature range on hospital admissions for cerebrovascular disease among farmers in Northwest China

Diurnal temperature range (DTR) is an appropriate indicator for reflecting climate change. Many previous studies have examined the relationship between DTR and mortality. Cerebrovascular disease (CVD) have a higher mortality than other diseases, with mortality from CVD higher in rural areas than in urban areas. A distributed lag non-linear model (DLNM) was used to analyze the exposure-effect relationship between DTR and hospital admissions for CVD from 2018 to 2020 in the population living in rural areas of Tianshui, Gansu Province, China. We investigated the effects of extreme DTR in groups stratified according to gender and age. A U-shape relationship was observed between DTR and hospital admissions for CVD. Both high DTR (19 °C) and low DTR (3 °C) were significantly associated significantly with CVD hospital admissions. When the lag period was 0-21 days, the impact of high DTR (1.595 [95% CI 1.301-1.957]) was slightly more significant than that of a low DTR (1.579 [95% CI - 1.202 to 2.075]). The effect of DTR on CVD varied in different populations. Males and adults were more sensitive to DTR than females and elderly people. It is necessary to make preventive measures to protect vulnerable populations from the adverse effects of extreme DTR.

Association between ambient temperature and cardiovascular disease hospitalisations among farmers in suburban northwest China

Cardiovascular disease (CVD) has become a severe public health and social issue in China. However, in northwest China, evidence on the association between ambient temperature and CVD hospitalisations in suburban farmers is somewhat limited. We collected CVD hospitalisations and meteorological data (2012-2015) in Zhangye suburbs and assessed the temperature-related risk and burden of admission by fitting a distributed lag nonlinear model to probe the relationship between ambient temperature and CVD hospitalisations among farmers in suburban northwest China. The results show that 23,921 cases of CVD admissions were recorded from 2012 to 2015. There was a "U-shaped" association between temperature and hospitalisations. Compared with the minimum admissions temperature (MAT) at 15.3 °C, the cumulative relative risk (RR) over lag 0-21 days was 1.369 (95% CI 0.980-1.911) for extreme cold temperature (1st percentile, -15 °C), 1.353 (95% CI 1.063-1.720) for moderate cold (5th percentile, -11 °C), 1.415 (95% CI 1.117-1.792) for extreme heat (99th percentile, 26 °C), and 1.241 (95% CI 1.053-1.464) for moderate heat (95th percentile, 24 °C). Female farmers were more susceptible to low and high temperatures than male farmers. Farmers aged ≥ 65 years old were more sensitive to low temperatures, while farmers aged < 65 years old were more sensitive to high temperatures. A total of 13.4% (3,208 cases) of the hospitalisation burden for CVD were attributed to temperature exposure, with the moderate range of temperatures accounting for the most significant proportion (12.2%). Ambient temperature, primarily moderate temperatures, might be an essential factor for cardiovascular-related hospitalisations among farmers in suburban northwest China.

Effects of diurnal temperature range on cardiovascular disease hospital admissions in farmers in China's Western suburbs

Cardiovascular disease (CVD), reported to relate with climate change, is the leading cause of global mortality and morbidity. Since the relevant information is quite limited from suburbs and countryside in developing and underdeveloped countries, there are no studies that focused on morbidity through diurnal temperature range (DTR) for these regions. This is the first study to evaluate the short-term effect of DTR on CVD hospital admission in suburban farmers, as well as to identify vulnerable subpopulations. Daily time series data of CVD hospital admissions on suburban farmers of Qingyang, China, and meteorological data from 2011 to 2015 were collected, and a distributed lag non-linear model (DLNM) combined with a quasi-Poisson generalized additive regression model (GAM) was used to examine the exposure-response relationship and delayed effect between DTR and CVD hospital admissions. Stratified analyses by age and gender were performed and extreme DTR effects were examined. Non-linear relation between DTR and CVD hospital admissions was observed, and whether DTR lower or higher than the reference (13 °C, 50^th percentile) had adverse effect while lower DTR have slightly higher impact. Also, both extreme low and extreme high DTR had adverse effect. Besides, adults (age < 65) and males were more vulnerable to the effects of DTR compared with the old (age ≥ 65) and females, respectively. This study provides evidence that not only high DTR but also low DTR had adverse effects on CVD which should be paid attention to. Adults and males were more vulnerable among suburban farmers. The results are inconsistent with the studies from urban and indicate differences between urban and suburban residents. Multiple factors such as occupations, risk awareness, and lifestyles could have a significant influence on CVD morbidity, and further study is needed to explore more evidence.

The effect and prediction of diurnal temperature range in high altitude area on outpatient and emergency room admissions for cardiovascular diseases

PURPOSE

Diurnal temperature range (DTR) is a meteorological indicator closely associated with global climate change. Thus, we aim to explore the effects of DTR on the outpatient and emergency room (O&ER) admissions for cardiovascular diseases (CVDs), and related predictive research.

METHODS

The O&ER admissions data for CVDs from three general hospitals in Jinchang of Gansu Province were collected from 2013 to 2016. A generalized additive model (GAM) with Poisson regression was employed to analyze the effect of DTR on the O&ER admissions for all cardiovascular diseases, hypertension, ischemic heart disease (IHD) and stoke. GAM was also used to preform predictive research of the effect of DTR on the O&ER admissions for CVDs.

RESULTS

There were similar positive linear relationships between DTR and the O&ER visits with the four cardiovascular diseases. And the cumulative lag effects were higher than the single lag effects. A 1 °C increase in DTR corresponded to a 1.30% (0.99-1.62%) increase in O&ER admissions for all cardiovascular diseases. Males and elderly were more sensitivity to DTR. The estimates in non-heating season were higher than in heating season. The trial prediction accuracy rate of CVDs based on DTR was between 59.32 and 74.40%.

CONCLUSIONS

DTR has significantly positive association with O&ER admissions for CVDs, which can be used as a prediction index of the admissions of O&ER with CVDs.

Mortality risk attributable to diurnal temperature range: a multicity study in Yunnan of southwest China

We aimed to estimate the non-accidental and cause-specific mortality burden attributed to diurnal temperature range (DTR) and the relative contributions of low, high, and extremely low and extremely high DTR in Yunnan, southwest China. Furthermore, we explored the possible effect modification of the DTR-mortality association by season, sex, age, ethnicity, marital status, and occupation. A standard time-series quasi-Poisson regression model combined with a distributed lag nonlinear model was used to derive estimates of city-specific DTR-mortality associations, then random effects meta-analysis was used to pool the estimated city-specific overall cumulative DTR-mortality association, estimating empirical confidence intervals (eCIs). The overall fraction of non-accidental mortality caused by DTR was 11.00% (95% eCI 3.40-17.28): high DTR accounted for most of burden (total estimate 10.03%, 95% eCI 2.59-16.32). The estimated mortality risk attributable to DTR was significantly associated with cardiovascular and respiratory mortality, with attributable fractions of 13.61% (95% eCI 3.91-21.13) and 14.32% (95% eCI 0.47-21.44), respectively. The estimated risk attributable to DTR was slightly greater for males, people ≥75 years old, married people, and non-farmers than their corresponding categories. Most of the DTR-related mortality burden was attributable to high DTR, and the mortality risk attributable to DTR might be modified by specific causes, sex, age, marital status, and occupation.

Effect modification of the association between diurnal temperature range and hospitalisations for ischaemic stroke by temperature in Hefei, China

OBJECTIVES

Diurnal temperature range (DTR) is an important indicator of global climate change. Many epidemiological studies have reported the associations between high DTR and human health. This study investigated the association between DTR and hospitalisations for ischaemic stroke in Hefei, China.

STUDY DESIGN

This is an ecological study.

METHODS

Data of daily hospital admissions for ischaemic stroke and meteorological variables from 1 January 2009 to 31 December 2017 were collected in Hefei, China. A generalised additive model combined with distributed lag non-linear model was used to quantify the effects of DTR on ischaemic stroke. The interactive effect between DTR and temperature was explored with a non-parametric bivariate response surface model.

RESULTS

High DTR was associated with hospitalisations for ischaemic stroke. The adverse effect of extremely high DTR (99th percentile [17.1 °C]) occurred after 8 days (relative risk [RR] = 1.021, 95% confidence interval [CI] = 1.002, 1.041) and the maximum effect appeared after 12 days (RR = 1.029, 95% CI = 1.011, 1.046). The overall trend of the effect of DTR on ischaemic stroke was decreasing. In addition, there was a significant interactive effect of high DTR and low temperature on ischaemic stroke.

CONCLUSIONS

This study suggests that the impact of high DTR should be considered when formulating targeted measures to prevent ischaemic stroke, especially for those days with high DTR and low mean temperature.

Impact of ambient temperature on cardiovascular disease hospital admissions in farmers in China's Western suburbs

Cardiovascular disease (CVD) has been a major threat to global public health. The association between temperature and CVD has been widely studied and reported in cities in developed countries. However, information from developing countries, especially from suburbs and countryside, is quite limited. In this study, the daily time series data on CVD hospital admissions in farmers in the suburbs of Tianshui, China, and the meteorological data from 2012 to 2015, were collected; besides, a quasi-Poisson regression with a distributed-lag non-linear model (DLNM) was used to explore the impact of local daily mean temperature on CVD hospital admissions in suburban farmers. This study found that, first, from 2011 to 2015, a total of 30,611 person-times of CVD hospital admissions in farmers were recorded; second, there was a "J-shaped" relation between temperature and CVD hospital admissions, and both low and high temperature increased the risk of hospital admission, but the impact of high temperature was greater; third, compared with the minimum hospitalization temperature (MHT) at 0.3 °C, during 0 to 21 lag days, the cumulative relative risk (RR) for extreme cold and heat (1st and 99th percentile of temperature, respectively) was 1.117 (95% CI 0.941-1.325) and 1.740 (95% CI 1.302-2.327), respectively, and that of moderate cold and heat (5st and 95th percentile of temperature, respectively) was 1.029 (95% CI 0.958-1.106) and 1.572 (95% CI 1.210-2.042), respectively; fourth, compared with male and ≥ 65 years groups, the risk for low temperature was greater for female and < 65 years groups, the risk for high temperature was just the opposite; last, about 21.04% of CVD hospital admissions burden were attributed to the ambient temperature, and most of (about 19.26%) were caused by moderate heat. In Tianshui, alongside with extreme temperature, the moderate temperature might be an important risk factor for CVD hospital admissions in suburban farmers.

The effect of diurnal temperature range on blood pressure among 46,609 people in Northwestern China

BACKGROUND

A large number of studies have found a positive association between diurnal temperature range (DTR) and cardiovascular diseases (CVDs) incidence and mortality. Few studies regarding the effects of DTR on blood pressure (BP) are available.

OBJECTIVE

To investigate the effects of DTR on BP in Jinchang, northwestern China.

METHODS

Based on a prospective cohort research, a total of 46,609 baseline survey data were collected from 2011 to 2015. The meteorological observation data and environmental monitoring data were collected in the same period. The generalized additive model (GAM) was used to estimate the relationship between DTR and BP after adjusting for confounding variables.

RESULTS

Our study found that there was a positive linear correlation between DTR and systolic blood pressure (SBP) and plus pressure (PP), and a negative linear correlation between DTR and diastolic blood pressure (DBP). With a 1 °C increase of DTR, SBP and PP increased 0.058 mmHg (95%CI: 0.018-0.097) and 0.114 mmHg (95%CI: 0.059-0.168) respectively, and DBP decreased 0.039 mmHg (95%CI:-0.065 ~ -0.014). There was a significant interaction between season and DTR on SBP and PP. DTR had the greatest impact on SBP and PP in hot season. The association between DTR and BP varied significantly by education level.

CONCLUSION

There was a significant association between DTR and BP in Jinchang, an area with large temperature change at high altitudes in northwestern China. These results provide new evidence that DTR is an independent risk factor for BP changes among general population. Therefore, effective control and management of BP in the face of temperature changes can help prevent CVDs.

Short-term effects of diurnal temperature range on hospital admission in Bangkok, Thailand

Diurnal temperature range (DTR) is a key indicator reflecting climate stability. Many previous studies have examined the effects of ambient temperature, both hot and cold, on human morbidity and mortality, but few studies have evaluated health effects of DTR, especially those in developing countries. This study aimed to investigate the association between short-term exposure to DTR and hospital admissions for cardiovascular and respiratory diseases in Bangkok, Thailand. We obtained daily meteorological variables from the Thai Meteorological Department from January 2006 through December 2014 and daily hospital admissions from the National Health Security Office during the same period. Quasi-Poisson generalized linear regression model combined with distributed lag non-linear model was used to examine the association between DTR and cardiovascular and respiratory hospital admissions controlling for daily average temperature, relative humidity, day of the week, public holiday, and seasonal and long-term trend. A J-shape relationship between DTR and hospital admissions was observed. With 7.8 °C DTR as a reference value, the relative risks for cardiovascular and respiratory hospital admission associated with extremely high DTR (11.6 °C) at cumulative lag 0-21 (21-day cumulative effects) were 1.206 (95% CI: 1.002-1.452) and 1.021 (95% CI: 0.856-1.218), respectively. The effects of extremely high DTR relative to a reference value did not significantly differ between males and females, as well as between young people (<65 years) and the elderly (≥65 years) for both cardiovascular and respiratory admission. When stratifying the effects by season, the effect of extremely high DTR in winter was greater than that in summer and rainy season. This study showed that short-term exposure to extremely high DTR was significantly associated with increased risk of hospital admissions for cardiovascular disease in Bangkok, especially during winter. Results from this study could provide important scientific evidence for policy decision making to protect populations from adverse health effects of DTR.

[Meteorological variables and air pollution and their association with hospitalizations due to respiratory diseases in children: a case study in São Paulo, Brazil]

Urban climate changes, excessive air pollution, and increasing social inequalities have become determinant factors in the high risk of hospitalizations due to respiratory diseases. The current study thus aimed to understand how meteorological factors (air temperature, relative humidity, and precipitation) and air pollution (particulate matter with aerodynamic diameter less than 10µm - PM10) are related to hospitalizations due to respiratory diseases in children in 14 districts in the city of São Paulo, Brazil. The combination of generalized linear models with a negative binomial distribution and distributed lag non-linear model (DLNM) were used as the statistical method to analyze the relationship between hospitalizations, climatic factors, and pollution from 2003 to 2013. The results show statistically significant association with high relative risk between mean air temperature (17.5ºC to 21ºC, for the total analyzed), relative humidity (84% to 98% for females), precipitation (0mm to 2.3mm for the total and both sexes and > 120mm for females), and PM10 (> 35µg/m³ for the total and for females). These results showed that environmental factors contribute to the high risk of hospitalizations.

Association of meteorological factors with infectious diarrhea incidence in Guangzhou, southern China: A time-series study (2006-2017)

BACKGROUND

Infectious diarrhea (ID) has exerted a severe disease burden on the world. The seasonal ID patterns suggest that meteorological factors (MFs) may influence ID incidence. The aim of this study was to evaluate the effect of MFs on ID, and to provide scientific evidence to the relevant health authorities for disease control and prevention.

METHODS

Data from ID cases and daily MFs (including mean temperature, diurnal temperature range, relative humidity, precipitation, atmospheric pressure, and wind velocity) in Guangzhou, Southern China from 2006 to 2017 were collected. Using a distributed lag non-linear model approach, we assessed the relationship between MFs and ID incidence.

RESULTS

Compared with the lowest ID risk values, low mean temperature, relative humidity, and precipitation were associated with an increased risk for ID, while higher diurnal temperature range and atmospheric pressure were also associated with increased risk. Maximum atmospheric pressure and minimum relative humidity had larger cumulative effects within 21 lag days, yielding relative risks of 133.11 (95% CI: 61.29-289.09) and 18.17 (14.42-22.89), respectively. The cumulative effect within 21 lag days of minimum temperature was higher than that from maximum temperature in all sub-populations. The cumulative effects of minimum temperature for men, teenagers, and young adults (10-29 years) were higher than those for other populations.

CONCLUSIONS

MFs should be considered when developing prevention and surveillance programs for ID. Special attention should be paid to vulnerable populations, such as teenagers and young adults.

Impact of ambient temperature on hospital admissions for cardiovascular disease in Hefei City, China

Many studies have quantified the hospitalization risk for cardiovascular disease (CVD) caused by temperature, but the results of most studies are not consistent. In this study, we evaluate the effect of temperature on CVD hospitalizations. We use a quasi-Poisson regression with a distributed-lag nonlinear model (DLNM) to evaluate the effect of temperature on CVD hospitalizations between July 1, 2015, and October 31, 2017, in Hefei City, China. We found that the cold effect and heat effect of temperature can impact CVD hospital admissions. Compared with the 25th percentile of temperature (10.3 °C), the cumulative relative risk (RR) of extremely low temperature (first percentile of temperature, 0.075 °C) over lags 0-27 days was 0.616 (95% CI 0.423-0.891), and the cumulative RR of moderate low temperature (10th percentile of temperature, 5.16 °C) was 1.081 (95% CI 1.019-1.147) over lags 0-7 days. Compared with the 75th percentile of temperature (25.6 °C), the cumulative RR of extremely high temperature (99th percentile of temperature, 33.7 °C) was 1.078 (95% CI 0.752-1.547) over lags 0-27 days, and the cumulative RR of moderate-high temperature (90th percentile of temperature, 29.0 °C) was 1.015 (95% CI 0.988-1.043) over lag 0 day. In the subgroup, the < 65-year group and male were more susceptible to low temperature; however, the ≥ 65-year group and female were more vulnerable to high temperature. The high temperature's impact on CVD hospital admissions was found to be more obvious in female and the ≥ 65-year group compared to male and the < 65-year group. However, the < 65-year group and men are more sensitive to low temperature.