A study of the short-term associations between hospital admissions and mortality from heart failure and meteorological variables in Hong Kong

Cold temperature-related attributable risk for emergency circulatory hospitalizations, length of stay, and healthcare costs in Hong Kong

BACKGROUND

The association of ambient temperature with the length of hospital stays and healthcare costs has not been well-explored. We aimed to examine the association of temperature with emergency hospital admission (EHA) count and length of stay (LOS) for total and cause-specific circulatory diseases and evaluate the temperature-related attributable risk and healthcare costs.

METHODS

This ecologic time series analysis linked the daily circulatory EHA count and LOS from the Hong Kong Hospital Authority with the environmental exposures from the fixed monitoring stations from 2004 to 2019. The generalized linear quasi-Poisson model integrated with a distributed lag nonlinear model was applied to examine ambient temperatures' relative and attributable risks on EHA counts and LOS while adjusting the time-varying confounders. Temperature-related healthcare costs were evaluated based on the estimated attributable number (AN) and charges per attendance or bed day.

RESULTS

Among 1276,632 EHAs and 7621,232 bed days of LOS, significant associations of cold temperatures with both EHA counts and LOS for total and cause-specific circulatory diseases were found. The temperature-related attributable fraction (AF) was estimated as 7.98 % (95 % CI: 5.24-10.58 %) for EHA count and 13.09 % (6.80-18.28 %) for LOS for total circulatory diseases. The cold temperature defined as the lower quartile of the ambient temperature range explained more than half of the temperature-related attributable risk and healthcare costs.

CONCLUSION

Cold weather can lead to adverse health outcomes, with considerable pressure on the healthcare system. Longer LOS-associated higher healthcare costs in colder weather may have implications for developing targeted preventions and hospital service planning.

Cardiovascular admission risk attributable to hot apparent temperature: a study in a rural area of northwest China

Cardiovascular disease (CVD) is the leading cause of mortality worldwide, posing a significant threat to public health. Research on the relationship between CVD and temperature has primarily focused on developed urban settings, with limited studies conducted in rural regions with lower levels of development. Additionally, compared to relative risks, attributable risks can provide more information when assessing the risk of CVD hospitalizations associated with exposure to apparent temperature (AT). Apparent temperature is a composite temperature index that takes into account both meteorological factors and temperature, providing an objective reflection of human thermal sensation. Therefore, this study investigates the impact of AT on CVD hospitalization and quantifies the burden of CVD admission in the rural areas of China. We employed the distributed lag non-linear model (DLNM) to estimate the relationship between AT and the relative risk (RR) of CVD hospitalization. Finally, we used attributable risk methods to quantify this relationship further.

Forecasting the Acute Heart Failure Admissions: Development of Deep Learning Prediction Model Incorporating the Climate Information

BACKGROUND

Climate is known to influence the incidence of cardiovascular events. However, their prediction with traditional statistical models remains imprecise.

METHODS AND RESULTS

We analyzed 27,799 acute heart failure (AHF) admissions within the Tokyo CCU Network Database from January 2014 to December 2019. High-risk AHF (HR-AHF) day was defined as a day with the upper 10th percentile of AHF admission volume. Deep neural network (DNN) and traditional regression models were developed using the admissions in 2014-2018 and tested in 2019. Explanatory variables included 17 meteorological parameters. Shapley additive explanations were used to evaluate their importance. The median number of incidences of AHF was 12 (9-16) per day in 2014-2018 and 11 (9-15) per day in 2019. The predicted AHF admissions correlated well with the observed numbers (DNN: R2 = 0.413, linear regression: R2 = 0.387). The DNN model was superior in predicting HR-AHF days compared with the logistic regression model [c-statistics: 0.888 (95% CI: 0.818-0.958) vs 0.827 (95% CI: 0.745-0.910): P = .0013]. Notably, the strongest predictive variable was the 7-day moving average of the lowest ambient temperatures.

CONCLUSIONS

The DNN model had good prediction ability for incident AHF using climate information. Forecasting AHF admissions could be useful for the effective management of AHF.

Association Between the Incidence of Hospitalizations for Acute Cardiovascular Events, Weather, and Air Pollution

Background

The incidence of hospitalizations for cardiovascular events has been associated with specific weather conditions and air pollution. A comprehensive model including the interactions between various environmental factors remains to be developed.

Objectives

The purpose of this study was to develop a comprehensive model of the association between weather patterns and the incidence of cardiovascular events and use this model to forecast near-term spatiotemporal risk.

Methods

We present a spatiotemporal analysis of the association between atmospheric data and the incidence rate of hospital admissions related to heart failure (922,132 episodes), myocardial infarction (521,988 episodes), and ischemic stroke (263,529 episodes) in ∼24 million people in Canada between 2007 and 2017. Our hierarchical Bayesian model captured the spatiotemporal distribution of hospitalizations and identified weather and air pollution-related factors that could partially explain fluctuations in incidence.

Results

Models that included weather and air pollution variables outperformed models without those covariates for most event types. Our results suggest that environmental factors may interact in complex ways on human physiology. The impact of environmental factors was magnified with increasing age. The weather and air pollution variables included in our models were predictive of the future incidence of heart failure, myocardial infarction, and ischemic strokes.

Conclusions

The increasing importance of environmental factors on cardiovascular events with increasing age raises the need for the development of educational materials for older patients to recognize environmental conditions where exacerbations are more likely. This model could be the basis of a forecasting system used for local, short-term clinical resource planning based on the anticipated incidence of events.

Association between ambient temperature and cause-specific cardiovascular disease admissions in Japan: A nationwide study

BACKGROUND

Substantial evidence suggests that non-optimal temperatures can increase the risk of cardiovascular disease (CVD) mortality and morbidity; however, limited studies have reported inconsistent results for hospital admissions depending on study locations, which also lack national-level investigations on cause-specific CVDs.

METHODS

We performed a two-stage meta-regression analysis to examine the short-term associations between temperature and acute CVD hospital admissions by specific categories [i.e., ischemic heart disease (IHD), heart failure (HF), and stroke] in 47 prefectures of Japan from 2011 to 2018. First, we estimated the prefecture-specific associations using a time-stratified case-crossover design with a distributed lag nonlinear model. We then used a multivariate meta-regression model to obtain national average associations.

RESULTS

During the study period, a total of 4,611,984 CVD admissions were reported. We found cold temperatures significantly increased the risk of total CVD admissions and cause-specific categories. Compared with the minimum hospitalization temperature (MHT) at the 98^th percentile of temperature (29.9 °C), the cumulative relative risks (RRs) for cold (5^th percentile, 1.7 °C) and heat (99^th percentile, 30.5 °C) on total CVD were 1.226 [95% confidence interval (CI): 1.195, 1.258] and 1.000 (95% CI: 0.998, 1.002), respectively. The RR for cold on HF [RR = 1.571 (95% CI: 1.487, 1.660)] was higher than those of IHD [RR = 1.119 (95% CI: 1.040, 1.204)] and stroke [RR = 1.107 (95% CI: 1.062, 1.155)], comparing to their cause-specific MHTs. We also observed that extreme heat increased the risk of HF with RR of 1.030 (95% CI: 1.007, 1.054). Subgroup analysis showed that the age group ≥85 years was more vulnerable to these non-optimal temperature risks.

CONCLUSIONS

This study indicated that cold and heat exposure could increase the risk of hospital admissions for CVD, varying depending on the cause-specific categories, which may provide new evidence to reduce the burden of CVD.

Ability to adapt to seasonal temperature extremes among atrial fibrillation patients. A nation-wide study of hospitalizations in Israel

BACKGROUND

In recent years, temperature fluctuations and adverse weather events have become major concerns, influencing overall mortality and morbidity. While the association between extreme temperatures and atrial fibrillation (AF) has been supported by research, there is limited evidence on the ability of AF patients to adapt to the changing temperatures. We explored this question among AF patients in Israel featured by extreme temperature conditions.

METHODS

We examined the association between exposure to extreme temperatures and hospitalizations related to AF in a nationwide cohort in Israel. A case-crossover design with a distributed nonlinear model (DLNM) was applied to assess possible effects of temperature fluctuations during each season. We considered the 7 days prior to the event as the possible window period.

RESULTS

During 2004-2018 we recorded a total of 54,909 hospitalizations for AF. Low temperatures in winter and high in summer adversely affected AF-related hospitalizations. The effect recorded for the first few weeks of each season was of higher magnitude and decreased or faded off completely as the seasons progressed (OR in winter: from 1.14, 95%CI 0.98, 1.32 to 0.90, 95%CI: 0.77, 1.06;OR in summer: from 1.95, 95%CI: 1.51, 2.52 to 1.22, 95%CI: 0.90, 1.65). Patients living in the south region and patients with low socioeconomic status were more susceptible to extreme temperatures.

CONCLUSIONS

Although extreme hot and cold temperatures are associated with an increased risk of hospitalization for AF, the patients are likely to adapt to temperature change over the course of the first weeks of the season.

Spatiotemporal relationship between temperature and non-accidental mortality: Assessing effect modification by socioeconomic status

BACKGROUND

Most published studies have assessed the overall health impact of temperature by using one-station or multiple-station averaged meteorological and air quality data. Concern has arisen about whether the temperature health impact is homogeneous across the whole territory geographically, since green space and socioeconomic factors may modify the impact.

OBJECTIVE

This study aims at investigating how small-area mortality is modified by local temperature and other meteorological, air quality, green space, and socioeconomic factors of small geographic units in a subtropical urban setting.

METHODS

Data on meteorological, air pollutants, and non-accidental mortality count in Hong Kong during 2006-2016 were obtained. Combined with green space and socioeconomic data, spatiotemporal analysis using Generalized Additive Mixed Models was conducted to examine the temperature-mortality relationship, adjusted for seasonality, long-term trend, other meteorological factors, pollutants, socioeconomic characteristics and green space.

RESULTS

Socioeconomic status was found to modify the temporal temperature-mortality relationship. A J-shape association was identified for most areas in Hong Kong, where a sharp increase of mortality was observed when daily minimum temperature dropped lower than the turning point. However, for people living in the most affluent areas, after the initial increase there was a decrease of mortality for colder days. Besides, when comparing the two spatiotemporal models (i.e. using nearby or central temperature monitoring station), while leaving the other predictors unchanged, this study showed that there was little difference in the overall model performances.

CONCLUSION

This study indicated that the daily fluctuation of mortality was associated with daily temperature, while the spatial variation of mortality within this city could be explained by the geographical distribution of green space and socioeconomic factors. Since people living in affluent areas were found to be more tolerant of cold temperatures, it would be more efficient to tailor cold temperature health education and warning information for socioeconomically deprived communities.

Health Disparity Resulting from the Effect of Built Environment on Temperature-Related Mortality in a Subtropical Urban Setting

Whereas previous studies have assessed the overall health impact of temperature in Hong Kong, the aim of this study was to investigate whether the health impact is modified by local temperature of small geographic units, which may be related to the diverse socioeconomic characteristics of these units. The effects of local temperature on non-accidental and cause-specific mortality were analyzed using Bayesian spatial models at a small-area level, adjusting for potential confounders, i.e., area-level air pollutants, socioeconomic status, and green space, as well as spatial dependency. We found that a 10% increase in green space density was associated with an estimated 4.80% decrease in non-accidental mortality risk and a 5.75% decrease in cardiovascular disease mortality risk in Hong Kong, whereas variation in local annual temperature did not significantly contribute to mortality. We also found that the spatial variation of mortality within this city could be explained by the geographic distribution of green space and socioeconomic factors rather than local temperature or air pollution. The findings and methodology of this study may help to further understanding and investigation of social and structural determinants of health disparities, particularly place-based built environment across class-based small geographic units in a city, taking into account the intersection of multiple factors from individual to population levels.

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.

Association of ambient temperature and acute heart failure with preserved and reduced ejection fraction

AIMS

Evidence on the association between ambient temperature and the onset of acute heart failure (AHF) is scarce and mixed. We sought to investigate the incidence of AHF admissions based on ambient temperature change, with particular interest in detecting the difference between AHF with preserved (HFpEF), mildly reduced (HFmrEF), and reduced ejection fraction (HFrEF).

METHODS AND RESULTS

Individualized AHF admission data from January 2015 to December 2016 were obtained from a multicentre registry (Tokyo CCU Network Database). The primary event was the daily number of admissions. A linear regression model, using the lowest ambient temperature as the explanatory variable, was selected for the best-estimate model. We also applied the cubic spline model using five knots according to the percentiles of the distribution of the lowest ambient temperature. We divided the entire population into HFpEF + HFmrEF and HFrEF for comparison. In addition, the in-hospital treatment and mortality rates were obtained according to the interquartile ranges (IQRs) of the lowest ambient temperature (IQR1 <5.5°C; IQR25.5-13.3°C; IQR3 13.3-19.7°C; and IQR4 >19.7°C). The number of admissions for HFpEF, HFmrEF and HFrEF were 2736 (36%), 1539 (20%), and 3354 (44%), respectively. The lowest ambient temperature on the admission day was inversely correlated with the admission frequency for both HFpEF + HFmrEF and HFrEF patients, with a stronger correlation in patients with HFpEF + HFmrEF (R²  = 0.25 vs. 0.05, P < 0.001). In the sensitivity analysis, the decrease in the ambient temperature was associated with the greatest incremental increases in HFpEF, followed by HFmrEF and HFrEF patients (3.5% vs. 2.8% vs. 1.5% per -1°C, P < 0.001), with marked increase in admissions of hypertensive patients (systolic blood pressure >140 mmHg vs. 140-100 mmHg vs. <100 mmHg, 3.0% vs. 2.0% vs. 0.8% per -1°C, P for interaction <0.001). A mediator analysis indicated the presence of the mediator effect of systolic blood pressure. The in-hospital mortality rate (7.5%) did not significantly change according to ambient temperature (P = 0.62).

CONCLUSIONS

Lower ambient temperature was associated with higher frequency of AHF admissions, and the effect was more pronounced in HFpEF and HFmrEF patients than in those with HFrEF.

Effect of apparent temperature on hospitalization from a spectrum of cardiovascular diseases in rural residents in Fujian, China

Cardiovascular disease (CVD) is a leading threat to global public health. Although associations between temperature and CVD hospitalization have been suggested for developed countries, limited evidence is available for developing countries or rural residents. Moreover, the effect of apparent temperature (AT) on the spectrum of cause-specific CVDs remains unknown. Based on 2,024,147 CVD hospitalizations for rural residents from eight regions in Fujian Province, China, during 2010-2016, a quasi-Poisson regression with distributed lag non-linear model was fitted to estimate the AT effect on daily CVD hospitalization for each region, and then pooled in a meta-regression that included regional indicators related to rural residents. Stratified analyses were performed according to the cause of hospitalization, sex and age groups. Finally, we calculated the fraction of CVD hospitalizations attributable to AT, as a reflection of the burden associated with AT. The heat effect appeared at lag 0-1 days, with 19% (95% CI, 11-26%) increased risk of CVD hospitalization, which was worse for ischemic heart disease, heart failure, arrhythmias and ischemic stroke. The decreased AT was associated with increase of hemorrhagic stroke at lag 0-28 days. People aged 65 and above suffered more from the heat effect on cardiovascular and cerebrovascular diseases. Regions with a lower gross value of agricultural production, rural residents' per capita net income, number of air conditioners and water heaters were more susceptible. A large number of hospitalizations were attributable to heat for most subcategories. High AT level increased CVD hospitalization, and the subcategories had different susceptibilities. The effects were modified by individual and regional characteristics. These findings have important implications for the development of targeted interventions and for hospital service planning.

A comparison of the effect of diurnal temperature range and apparent temperature on cardiovascular disease among farmers in Qingyang, Northwest China

Climate change is increasing the incidence of extreme weather events which have a significant impact on public health. Cardiovascular diseases (CVDs) are the number one cause of death globally (40%). Apparent temperature (AT) and diurnal temperature range (DTR) have been extensively used to evaluate the effects of temperature on cardiovascular disease (CVD). However, the relevant information is quite limited from analysis and comparison of effects and differing pathogenesis of DTR and AT on CVD especially in less-developed, rural areas of China. This is the first attempt to analyze different effects between AT and DTR on CVD using distributed lag nonlinear modeling (DLNM) in rural area. Data on CVD hospital admission in Qingyang (Northwest China) in 2014-2017 originated from the New Rural Cooperative Medical System (NRCMS) of Gansu Province, and meteorological variables were provided by the Meteorological Science Data Sharing Service. Both AT and DTR had significant nonlinear and delayed impacts on hospital admissions for CVD. DTR had a stronger and more persistent effect on CVD incidence than AT. Females were more affected by high AT and low DTR than were males, while males were more vulnerable to low AT and high DTR. Temperature effects were not significantly different between people above and below 65 years of age. These findings provide local public health authorities with reference concerning sensitive temperature indices for susceptible populations with a view to improve CVD preventive strategies in rural areas.

Relationship between acute kidney injury, seasonal influenza, and environmental factors: A 14-year retrospective analysis

Despite high incidence of acute kidney injury (AKI) among patients hospitalised for influenza, no previous work has attempted to analyse and quantify the association between the two. Herein, we made use of Hong Kong's surveillance data to evaluate the time-varying relationship between seasonal influenza and risk of AKI with adjustment for potential environmental covariates. Generalized additive model was used in conjunction with distributed-lag non-linear model to estimate the association of interest with daily AKI admissions as outcome and daily influenza admissions as predictor, while controlling for environmental variables (i.e. temperature, relative humidity, total rainfall, nitrogen dioxide, and ozone). Results suggested a positive association between risk of AKI admission and number of influenza hospitalisation cases, with relative risk reaching 1.12 (95% confidence interval, 1.10-1.15) at the 95th percentile. Using median as reference, an almost U-shaped association between risk of AKI admission and temperature was observed; the risk increased significantly when the temperature was low. While ozone was not shown to be a risk factor for AKI, moderate-to-high levels of nitrogen dioxide (50-95th percentile) were significantly associated with increased risk of AKI admission. This study mentioned the possibility that AKI hospitalisations are subject to environmental influences and offered support for a positive association between seasonal influenza and AKI occurrence in Hong Kong. Authorities are urged to extend the influenza vaccination program to individuals with pre-existing renal conditions to safeguard the health of the vulnerable. Given that adverse health effects are evident at current ambient levels of nitrogen dioxide, the government is recommended to adopt clean-air policies at the earliest opportunity to protect the health of the community.

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 Mortality Risk and Socioeconomic Vulnerability Associated with High and Low Temperature in Hong Kong

(1) Background: The adverse health effect associated with extreme temperature has been extensively reported in the current literature. Some also found that temperature effect may vary among the population with different socioeconomic status (SES), but found inconsistent results. Previous studies on the socioeconomic vulnerability of temperature effect were mainly achieved by multi-city or country analysis, but the large heterogeneity between cities may introduce additional bias to the estimation. The linkage between death registry and census in Hong Kong allows us to perform a city-wide analysis in which the study population shares virtually the same cultural, lifestyle and policy environment. This study aims to examine and compare the high and low temperature on morality in Hong Kong, a city with a subtropical climate and address a key research question of whether the extreme high and low temperature disproportionally affects population with lower SES. (2) Methods: Poisson-generalized additive models and distributed-lagged nonlinear models were used to examine the association between daily mortality and daily mean temperature between 2007–2015 with other meteorological and confounding factors controlled. Death registry was linked with small area census and area-level median household income was used as the proxy for socioeconomic status. (3) Results: 362,957 deaths during the study period were included in the analysis. The minimum mortality temperature was found to be 28.9 °C (82nd percentile). With a subtropical climate, the low temperature has a stronger effect than the high temperature on non-accidental, cardiovascular, respiratory and cancer deaths in Hong Kong. The hot effect was more pronounced in the first few days, while cold effect tended to last up to three weeks. Significant heat effect was only observed in the lower SES groups, whilst the extreme low temperature was associated with significantly higher mortality risk across all SES groups. The older population were susceptible to extreme temperature, especially for cold. (4) Conclusions: This study raised the concern of cold-related health impact in the subtropical region. Compared with high temperature, low temperature may be considered a universal hazard to the entire population in Hong Kong rather than only disproportionally affecting people with lower SES. Future public health policy should reconsider the strategy at both individual and community levels to reduce temperature-related mortality.

Ambient temperature, seasonal influenza and risk of cardiovascular disease in a subtropical area in Southern China

BACKGROUND

Given the regular winter recurrence of influenza epidemics and the biologically plausible association between seasonal influenza and cardiovascular events, researchers assumed a valid and reliable influenza forecast could envision the timing and burden of winter surge in cardiovascular (CVD) hospitalizations. This, however, is well justified only in temperate regions. In this study, we aim to investigate the temporal association between ambient temperature, seasonal influenza and risk of cardiovascular events in a subtropical city.

METHODS

Generalized additive model was used in conjunction with distributed-lag non-linear model of quasi-Poisson family to estimate the association of interest with daily CVD admissions as outcome and daily influenza admissions as predictor, while controlling for meteorological factors (i.e. temperature, relative humidity, wind speed and total rainfall) and respiratory pollutants (i.e. nitrogen dioxide, sulphur dioxide, ozone and PM₁₀). Results were expressed in the form of relative risk (RR).

RESULTS

Using median as the reference value, a U-shaped association was observed between CVD admissions and temperature. A slight decrease in RR was detected mainly towards the lower end of the temperature scale after adjusting for influenza admissions. Risk of CVD admission was found to be positively associated with the number of influenza hospitalization cases; this association remained consistent and statistically significant across subgroups of age except for those aged 5-49 years.

CONCLUSION

The slight reduction in CVD admission risk towards the lower end of the temperature scale after controlling for influenza activity might be attributed to the winter peaks of influenza, meaning that the effect of low temperature on CVD admissions might be partly mediated by influenza infection. In summary, this study reassures us that ambient temperature is independently associated with CVD hospital admissions and offers support for a positive association between seasonal influenza activity and cardiovascular events in Hong Kong.

Comparative assessments of mortality from and morbidity of circulatory diseases in association with extreme temperatures

BACKGROUND

This study evaluated vulnerable subpopulation on mortality, emergency room visits (ERVs) and outpatient visits associated with ambient daily temperature from 2000 to 2014 using vital statistics and insurance claims of Taiwan.

METHODS

We used the distributed lag non-linear model to assess circulatory disease-specific deaths, ERVs, and outpatient visits by mean temperature after controlling particulate matter (PM₁₀) and other covariates. Lag effect of temperature changes on health risks accumulated for 0-10 days associated with low temperature and for 0-5 days for high temperature were evaluated. Cause-specific pooled relative risk (RR) and 95% confidence intervals (CI) were estimated for the whole population of Taiwan using random-effects meta-analysis.

RESULTS

We used reference temperatures of 60th percentiles for mortality from circulatory diseases, 99th percentile for ERVs of circulatory diseases, 2nd percentile for ERVs of heart diseases and ischemic heart disease, 53th percentile for ERVs of cerebrovascular disease, and 12-16th percentiles for outpatient visits of circulatory diseases. The lag effects peaked at lag 4-5 day for low temperature exposure and at lag 0 for high temperature exposure. Pooled cold related health risk was the highest for mortality from and ERV of circulatory diseases with RR of 1.41 (95% CI: 1.34, 1.49) and 1.41 (95% CI: 1.35, 1.48), respectively, as daily mean temperatures was at 1st percentile (12.8 °C). Heat related health risk was significant for mortality from heart diseases [RR = 1.12 (95% CI: 1.07, 1.18)] and ischemic heart diseases [RR = 1.13 (95% CI: 1.06, 1.20)] as daily mean temperatures was at 99th percentile (29.9 °C).

CONCLUSIONS

Health authority should evaluate the effectiveness of adaptive policy, strategy, and actions responding to extreme temperatures to prevent mortality from circulatory diseases.

The effects of weather on daily emergency ambulance service demand in Taipei: a comparison with Hong Kong

Numerous studies have examined the effects of weather on emergency ambulance service (EAS) demand. Given Taipei's unique physical and social environments, empirical evidence collected from other regions may not be applicable. Collecting more information about the characteristics of vulnerable groups and the effects of weather could help the EAS managing authority in formulating cost-effective EAS policies. This study aims to look at the effects of weather on EAS demand in Taipei and to make a comparison with Hong Kong, which is also an Asian city and has a similar cultural context. The study analyzed over 370,000 EAS usage records from the Taipei City Fire Department. These records were aggregated into time series data according to patients' characteristics and then regressed on meteorological data via multivariate forward regression. The effect size differences of the variance explained by different groups of EAS users' regression models were compared. Afterward, the results of the regression analysis from Taipei were compared with those from a Hong Kong study. Elderly and critical patients in both cities showed significantly more sensitivity to weather than other patients. Further analysis showed that non-trauma cases were related to weather in Taipei. Although both cities had similar results, the Taipei study clearly showed that elderly and critical patients were more sensitive to weather than other patient subgroups. Health education programs should focus on the vulnerable groups identified in this study in order to increase their awareness and help them protect themselves before the onset of adverse weather conditions. By generating results that are directly applicable to Taipei, the formulation of inappropriate EAS policies can be prevented.

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.

Quantification of Seasonal Variation in Daily Physical Activity in Individuals with Heart Failure and Implantable Cardioverter Defibrillator/Cardiac Resynchronisation Therapy Devices

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Management decision of hospital surge: assessing seasonal upsurge in inpatient medical bed occupancy rate among public acute hospitals in Hong Kong

BACKGROUND

There were recurrent upsurges in demand for public hospital services in Hong Kong. An understanding of the contribution of some possible factors for the rise in health care burden would help to inform hospital management strategies.

AIM

To evaluate the utilization patterns of hospitalizations in medical wards among public acute hospitals in Hong Kong during surge periods.

DESIGN

Retrospective study.

METHODS

By extracting the information in press releases between 2014 and 2018, descriptive statistics about medical ward occupancy situation during six surge periods were generated. A time series model was constructed to estimate the occupancy rate at each hospital and assess its relationship with the intensity of seasonal influenza activity, extreme weather, day of week and long holidays.

RESULTS

There was a significant increase in the number of admissions to medical wards in all six surge periods. A significant variation in occupancy rate between weekdays and geographic regions was observed. The occupancy rate in 10, out of 15, hospitals was significantly associated with the influenza activity, while there was limited effect of weather on the occupancy rate. A significant holiday effect was observed during Christmas and Chinese New Year, resulting in a lower bed occupancy rate.

CONCLUSIONS

A differential burden in public hospitals during surge periods was reported. Contingency bed and staff management shall be tailored to individual hospitals, given their differences in the determinants for inpatient bed occupancy.

Association between Ambient Temperatures and Mental Disorder Hospitalizations in a Subtropical City: A Time-Series Study of Hong Kong Special Administrative Region

Background: Mental disorders have been found to be positively associated with temperature in cool to cold climatic regions but the association in warmer regions is unclear. This study presented the short-term association between temperatures and mental disorder hospitalizations in a subtropical city with a mean annual temperature over 21 °C. Methods: Using Poisson-generalized additive models and distributed-lagged nonlinear models, daily mental disorder hospitalizations between 2002 and 2011 in Hong Kong were regressed on daily mean temperature, relative humidity, and air pollutants, adjusted for seasonal trend, long-term trend, day-of-week, and holiday. Analyses were stratified by disease class, gender and age-group. Results: 44,600 admissions were included in the analysis. Temperature was positively associated with overall mental-disorder hospitalizations (cumulative relative risk at 28 °C vs. 19.4 °C (interquartile range, lag 0-2 days) = 1.09 (95% confidence interval 1.03, 1.15)), with the strongest effect among the elderly (≥75 years old). Transient mental disorders due to conditions classified elsewhere and episodic mood disorders also showed strong positive associations with temperature. Conclusion: This study found a positive temperature-mental-disorder admissions association in a warm subtropical region and the association was most prominent among older people. With the dual effect of global warming and an aging population, targeted strategies should be designed to lower the disease burden.

Mining telemonitored physiological data and patient-reported outcomes of congestive heart failure patients

This paper addresses patient-reported outcomes (PROs) and telemonitoring in congestive heart failure (CHF), both increasingly important topics. The interest in CHF trials is shifting from hard end-points such as hospitalization and mortality, to softer end-points such health-related quality of life. However, the relation of these softer end-points to objective parameters is not well studied. Telemonitoring is suitable for collecting both patient-reported outcomes and objective parameters. Most telemonitoring studies, however, do not take full advantage of the available sensor technology and intelligent data analysis. The Chiron clinical observational study was performed among 24 CHF patients (17 men and 7 women, age 62.9 ± 9.4 years, 15 NYHA class II and 9 class III, 10 of ishaemic, aetiology, 6 dilated, 2 valvular, and 6 of multiple aetiologies or cardiomyopathy) in Italy and UK. A large number of physiological and ambient parameters were collected by wearable and other devices, together with PROs describing how well the patients felt, over 1,086 days of observation. The resulting data were mined for relations between the objective parameters and the PROs. The objective parameters (humidity, ambient temperature, blood pressure, SpO2, and sweeting intensity) could predict the PROs with accuracies up to 86% and AUC up to 0.83, making this the first report providing evidence for ambient and physiological parameters to be objectively related to PROs in CHF patients. We also analyzed the relations in the predictive models, gaining some insights into what affects the feeling of health, which was also generally not attempted in previous investigations. The paper strongly points to the possibility of using PROs as primary end-points in future trials.

Association between Weather-Related Factors and Cardiac Arrest of Presumed Cardiac Etiology: A Prospective Observational Study Based on Out-of-Hospital Care Data

OBJECTIVE

The objective of this study was to determine the association between weather-related factors and out-of-hospital cardiac arrest (OHCA) of presumed cardiac etiology.

METHODS

This was a prospective observational study performed in a prehospital setting. Data from the Emergency Medical Service in Hamburg (Germany) and data from the local weather station were evaluated over a 5-year period. Weather data (temperature, humidity, air pressure, wind speed) were obtained every minute and matched with the associated rescue mission data. Lowess-Regression analysis was performed to assess the relationship between the above-mentioned weather-related factors and OHCA of presumed cardiac etiology. Additionally, varying measuring-ranges were defined for each weather-related factor in order to compare them with each other with regard to the probability of occurrence of OHCA.

RESULTS

During the observation period 1,558 OHCA with presumed cardiac etiology were registered (age: 67 ± 19 yrs; 62% male; hospital admission: 37%; survival to hospital discharge: 6.7%). Compared to moderate temperatures (5 - 25°C), probability of OHCA-occurrence increased significantly at temperatures above 25°C (p = 0.028) and below 5°C p = 0.011). Regarding air humidity, probability of OHCA-occurrence increased below a threshold-value of 75% compared to values above this cut-off (p = 0.006). Decreased probability was seen at moderate atmospheric pressure (1000 hPa - 1020 hPa), whereas increased probability was seen above 1020 hPa (p = 0.023) and below 1000 hPa (p = 0.035). Probability of OHCA-occurrence increased continuously with increasing wind speed (p < 0.001).

CONCLUSIONS

There are associations between several weather-related factors such as temperature, humidity, air pressure, and wind speed, and occurrence of OHCA of presumed cardiac etiology. Particularly dangerous seem to be cold weather, dry air and strong wind.

Increased hospitalizations for decompensated heart failure and acute myocardial infarction during mild winters: A seven-year experience in the public health system of the largest city in Latin America

BACKGROUND

In high-income temperate countries, the number of hospitalizations for heart failure (HF) and acute myocardial infarction (AMI) increases during the winter. This finding has not been fully investigated in low- and middle-income countries with tropical and subtropical climates. We investigated the seasonality of hospitalizations for HF and AMI in Sao Paulo (Brazil), the largest city in Latin America.

METHODS

This was a retrospective study using data for 76,474 hospitalizations for HF and 54,561 hospitalizations for AMI obtained from public hospitals, from January 2008 to April 2015. The average number of hospitalizations for HF and AMI per month during winter was compared to each of the other seasons. The autoregressive integrated moving average (ARIMA) model was used to test the association between temperature and hospitalization rates.

FINDINGS

The highest average number of hospital admissions for HF and AMI per month occurred during winter, with an increase of up to 30% for HF and 16% for AMI when compared to summer, the season with lowest figures for both diseases (respectively, HF: 996 vs. 767 per month, p<0.001; and AMI: 678 vs. 586 per month, p<0.001). Monthly average temperatures were moderately lower during winter than other seasons and they were not associated with hospitalizations for HF and AMI.

INTERPRETATION

The winter season was associated with a greater number of hospitalizations for both HF and AMI. This increase was not associated with seasonal oscillations in temperature, which were modest. Our study suggests that the prevention of cardiovascular disease decompensation should be emphasized during winter even in low to middle-income countries with tropical and subtropical climates.

Effects of climate and fine particulate matter on hospitalizations and deaths for heart failure in elderly: A population-based cohort study

BACKGROUND

There are limited data on the effects of climate and air pollutant exposure on heart failure (HF) within taking into account individual and contextual variables.

OBJECTIVES

We measured the lag effects of temperature, relative humidity, atmospheric pressure and fine particulate matter (PM_2.5) on hospitalizations and deaths for HF in elderly diagnosed with this disease on a 10-year period in the province of Quebec, Canada.

METHODS

Our population-based cohort study included 112,793 elderly diagnosed with HF between 2001 and 2011. Time dependent Cox regression models approximated with pooled logistic regressions were used to evaluate the 3- and 7-day lag effects of daily temperature, relative humidity, atmospheric pressure and PM_2.5 exposure on HF morbidity and mortality controlling for several individual and contextual covariates.

RESULTS

Overall, 18,309 elderly were hospitalized and 4297 died for the main cause of HF. We observed an increased risk of hospitalizations and deaths for HF with a decrease in the average temperature of the 3 and 7days before the event. An increase in atmospheric pressure in the previous 7days was also associated with a higher risk of having a HF negative outcome, but no effect was observed in the 3-day lag model. No association was found with relative humidity and with PM_2.5 regardless of the lag period.

CONCLUSIONS

Lag effects of temperature and other meteorological parameters on HF events were limited but present. Nonetheless, preventive measures should be issued for elderly diagnosed with HF considering the burden and the expensive costs associated with the management of this disease.