Associations of cold exposure with hospital admission and mortality due to acute kidney injury: A nationwide time-series study in Korea

Association between air pollution and hospitalization for acute exacerbation of kidney failure: A nationwide time-stratified case-crossover study in China

BACKGROUND

Air pollution is a potential risk factor for kidney disease; however, the impact on kidney failure exacerbation is underexplored. This study assessed the short-term effects of air pollution on hospitalization for kidney failure exacerbation.

METHODS

This nationwide, time-stratified, case-crossover study included 45,249 hospitalized patients with kidney failure from 153 hospitals in 20 Chinese provinces between 2013 and 2020. Air pollutant concentrations were obtained from the closest monitoring stations. Conditional logistic regression models were used to determine the associations between air pollutants and hospitalizations, with exposure-response curves fitted and stratified analyses conducted.

RESULTS

For each interquartile range increase in pollutants (lag 0-2 days), there was a significant increase in kidney failure hospitalization: 3.46 % for PM2.5, 3.64 % for PM2.5-10, 7.88 % for NO2, and 4.37 % for CO. No significant associations were observed for O3 and SO2. NO2 had a linear exposure-response curve; PM2.5 and PM2.5-10 showed stronger effects at lower exposures, while CO's effect increased at higher exposures. Furthermore, the impact was greater during the cold season.

CONCLUSIONS

This large-scale national study highlights the significant association between short-term exposure to PM2.5, PM2.5-10, NO2, and CO and kidney failure exacerbation, providing novel insights into the combined effects of air pollution on kidney failure.

Double disparities of the excess risks and costs of extreme temperatures on hospitalization between Medical Aid and non-Medical Aid populations in South Korea

BACKGROUND

Previous studies have reported simple differences in extreme temperature-related health risks by low socioeconomic status; however, few have examined in depth the double disparities in the socially marginalized people by age groups, sexes, disabilities, and causes of hospitalization. This study examined (i) the differences between heat- and cold-related risks on hospitalization between people who are eligible and non-eligible for the medical aid system in the national health insurance service system and (ii) differences between the heat- and cold-related risk and cost differences by specific subgroups in South Korea.

METHODS

We collected population-based longitudinal cohort data from the National Health Insurance Service-National Health Insurance Database from 2010 to 2019. The data included all individuals who were eligible for the Korean Medical Aid (MA) system during the study period and we used their data on hospitalization through the emergency department (ED). As a control group, we collected age-sex-residential address-matched individuals who were not eligible for the MA system. We adopted a case-crossover design with a distributed lag nonlinear model to evaluate the excess risks and costs associated with cold and heat temperatures on hospital admissions via the emergency room department.

RESULTS

During the study period, 509 480 hospital admissions via the ED were recorded among 1 466 176 beneficiaries who were eligible for MA. Among the MA beneficiaries, the estimated risk for ED admission that was attributable to heat was 1.19 [95% confidence interval (CI): 1.14-1.24] and the risk that was attributable to cold temperature was 1.52 (95% CI: 1.43-1.61), which were both higher than those of the control groups that incorporated matched beneficiaries who were not eligible for MA. For both heat and cold, the difference between MA and non-MA was prominent in non-elderly populations, males, people with disabilities, and admissions with mental and cardiovascular diseases.

CONCLUSION

This study revealed the hypothesis that the differences between heat- and cold-related risks in the socially marginalized population existed and suggested that the disparities might also be disproportionate by socioeconomic and demographic statuses.

Modification of the association between cold spells and cardiovascular disease by changes in natural gas prices: A nationwide time-series study

BACKGROUND

Although the association between low ambient temperature and cardiovascular disease (CVD) is well-established, the effect of winter energy prices on this association remains unknown.

AIM

This ecological study aimed to investigate whether changes in natural gas prices (NGP), which account for a significant portion of winter energy prices in Korea, affect the association of cold spells with hospital admissions and mortality due to CVD.

METHODS

Data from the National Health Insurance Service and Statistics Korea were used to determine the daily number of hospital admissions and mortality rates associated with CVD. From January 2012 to February 2017, the NGP continually increased by 24.1%. From January 2012 to December 2014 the NGP continually decreased by 32.6% owing to the Korea Gas Corporation's management decisions, independent of external socioeconomic factors. We investigated the differences in the associations between cold spells and CVD-related outcomes in price-increasing and price-decreasing periods using a Poisson regression with a distributed lag nonlinear model. Cold spells were assessed on two consecutive days at the 5th percentile of the temperature for each region.

RESULTS

The meteorological factors and air pollution levels were similar between the two periods. The association between cold spells and hospital admissions due to CVD was stronger during the price-increasing period than during the price-decreasing period [ratio of cumulative relative risk (RRR) = 1.71, 95% confidence interval (CI): 1.31-2.22]. The difference in the association with mortality due to CVD between the two periods was not significant, although the point estimate remained >1 (RRR = 1.11, 95% CI: 0.90-1.38).

CONCLUSIONS

Changes in energy prices may modify the cold spell-related CVD risk, possibly by inducing behavioral changes to manage energy expenditure. Policymakers should take into account the potential public health implications of changes in energy prices, alongside their economic effects.

Extreme temperature events, "Life's Essential 8", and prevalence of chronic kidney disease: A nationally representative surveillance in China

The population disease burden caused by extreme temperature events has been increasing. However, research on the long-term effects of extreme temperature events on chronic kidney disease (CKD), as well as the combined effects with individual behaviors and metabolic factors is still lacking. Based on 176,874 participants from the most recent nationally representative surveillance on CKD and validated high spatial resolution (0.1°) remote-sensing products, this study investigated the associations between extreme temperature events in the preceding five years before investigation and CKD (defined by reduced renal function or albuminuria) prevalence. We also investigated the associations between "Life's Essential 8", a recognized scale to evaluate overall cardiovascular health (CVH) based on individual behaviors and metabolic indicators and CKD prevalence, as well as its combined effects with extreme temperature events. One additional day of heat waves and cold spells per year was associated with increased ORs of CKD [1.10 (95 % CI: 1.08, 1.11) and 1.07 (95 % CI: 1.05, 1.09), respectively]. Meanwhile, per standard deviation (SD) increment in health behavior score (SD = 16.1), health factor score (SD = 18.4), and overall CVH score (SD = 12.4) were associated with decreased ORs of CKD [0.92 (95 % CI: 0.90, 0.93), 0.60 (95 % CI: 0.59, 0.61), and 0.64 (95 % CI: 0.63, 0.65, respectively]. Relative to higher heat wave & lower CVH score group, the ORs of CKD were 0.87 (95 % CI: 0.84, 0.90), 0.51 (95 % CI: 0.48, 0.53), and 0.42 (95 % CI: 0.40, 0.44) in lower & lower, higher & higher, and lower & higher group, respectively. Our findings underscore the importance of considering the synergistic effects of individual behavioral and metabolic factors for strategies to mitigate the impacts of climate change on CKD.

The effect of ambient temperatures on hospital admissions for kidney diseases in Central Australia

This study aimed to quantify risk of hospitalisations for kidney diseases related to ambient temperature in Central Australia, Northern Territory (NT). Daily hospitalisation data were extracted for Alice Springs Hospital, Central Australia, 2010-2021. The association between daily mean temperature and daily hospital admissions for total kidney and specific kidney conditions was assessed using a quasi-Poisson Generalized Linear Model combined with a distributed lag non-linear model. A total of 52,057 hospitalisations associated with kidney diseases were recorded. In general, risk of specific kidney related hospitalisations was immediate due to hot temperatures and prolonged due to cold temperatures. Relative to the minimum-risk temperature (5.1 °C), at 31 °C, cumulative relative risk (RR) of hospitalisations for total kidney disease (TKD) was 1.297 [95% CI 1.164,1.446] over lag0-1 days, for chronic kidney disease (CKD) cumulative RR was 1.269 [95% CI 1.115,1.444] and for kidney failure (KF) cumulative RR was 1.252 [95% CI 1.107,1.416] at lag 0, and for urinary tract infection (UTI) cumulative RR was 1.522 [95% CI 1.072,2.162] over lag0-7 days. At 16 °C and over lag0-7 days, cumulative RR of hospitalisations for TKD was 1.320 [95% CI 1.135,1.535], for CKD was 1.232 [95% CI 1.025,1.482], for RF was 1.233 [95% CI 1.035,1.470] and for UTI was 1.597 [95% CI 1.143, 2.231]. Both cold and hot temperatures were also associated with increased risks of kidney related total hospitalisations among First Nations Australians and women. Overall, temperature attributable to 13.7% (i.e. 7138 cases) of kidney related hospitalisations with higher attributable hospitalisations from cold temperature. Given the significant burden of kidney disease and projected increases in extreme temperatures associated with climate change in NT including Central Australia there is a need to implement public health and environmental health risk reduction strategies and awareness programs to mitigate potential adverse health effects of extreme temperatures.

Association Between Influenza Vaccination and Acute Kidney Injury Among the Elderly: A Self-Controlled Case Series

BACKGROUND

Several cases of renal complications, including acute kidney injury (AKI), after influenza vaccination have been reported, but the association remains unproven. We evaluated the association between influenza vaccination and AKI occurrence among the Korean elderly in the 2018-2019 and 2019-2020 seasons.

METHODS

We used a large database combining vaccination registration data from the Korea Disease Control and Prevention Agency and claims data from the National Health Insurance Service. The study subjects were patients hospitalized with AKI for the first-time following vaccination among those who received one influenza vaccine in the 2018-2019 or 2019-2020 season. Only those aged 65 or older at the date of vaccination were included. We performed a self-controlled case series study, designating the risk period as 1 to 28 days post-vaccination and the observation period as each influenza season. The adjusted incidence rate ratio (aIRR) was calculated by adjusting for nephrotoxic drug use and influenza infection that may influence AKI occurrence using a conditional Poisson regression model.

RESULTS

A total of 16 713 and 16 272 AKI events were identified during the 2018-2019 and 2019-2020 seasons, respectively. The aIRR for AKI was 0.83 (95% confidence interval [CI] = 0.79-0.87) in the 2018-2019 season. The aIRR for the 2019-2020 influenza season was similar to the 2018-2019 season (aIRR = 0.86; 95% CI = 0.82-0.90).

CONCLUSIONS

Influenza vaccination is associated with a lower risk of AKI in the elderly over 65. This evidence supports the recommendation of annual influenza vaccination for the elderly. Further studies are needed to determine the biological mechanisms linking the influenza vaccine and AKI.

Association between ambient temperature and genitourinary emergency ambulance dispatches in Japan: A nationwide case-crossover study

Background

Although the effects of temperature on genitourinary morbidity and mortality have been investigated in several countries, it remains largely unexplored in Japan. We investigated the association between ambient temperature and genitourinary emergency ambulance dispatches (EADs) in Japan and the modifying roles of sex, age, and illness severity.

Methods

We conducted a time-stratified case-crossover study with conditional quasi-Poisson regression to estimate the association between mean temperature and genitourinary EADs in all prefectures of Japan between 2015 and 2019. A mixed-effects meta-analysis was used to pool the association at the country level. Subgroup analyses were performed to explore differences in associations stratified by sex, age, and illness severity.

Results

We found an increased risk of genitourinary EAD associated with higher temperatures. The cumulative relative risk (RR) at the 99th temperature percentile compared with that at the 1st percentile was 1.74 (95% confidence interval (CI) = [1.60, 1.89]). We observed higher heat-related RRs in males (RR = 1.89; 95% CI = [1.73, 2.07]) than females (RR = 1.56; 95% CI = [1.37, 1.76]), and in the younger (RR = 2.13; 95% CI = [1.86, 2.45]) than elderly (RR = 1.39; 95% CI = [1.22, 1.58]). We found a significant association for those with mild or moderate cases (RR = 1.77; 95% CI = [1.62, 1.93]), but not for severe or life-threatening cases (RR = 1.20; 95% CI = [0.80, 1.82]).

Conclusion

Our study revealed heat effects on genitourinary EADs in Japan. Men, youth, and mild-moderate illnesses were particularly vulnerable subgroups. These findings underscore the need for preventative measures aimed at mitigating the impact of temperature on genitourinary emergencies.

Ambient heat and acute kidney injury: case-crossover analysis of 1 354 675 automated e-alert episodes linked to high-resolution climate data

BACKGROUND

As global temperatures continue to rise, the effects of ambient heat on acute kidney injury (AKI) are of growing concern. We used a novel nationwide electronic alert (e-alert) system to detect increases in AKI risk associated with high temperatures.

METHODS

We used a case-crossover design to link 1 354 675 AKI episodes occurring in England between April and September in years 2017-2021 to daily maximum temperature data at postcode sector level. AKI episode data were obtained from the UK Renal Registry. There were no further inclusion or exclusion criteria. Conditional logistic regression employing distributed lag non-linear models was used to assess odds of AKI episode on case days compared with day-of-week matched control days. Effects during heatwaves were also assessed using heat-episode analysis.

FINDINGS

There were strongly increased odds of AKI episode associated with high temperatures, with odds ratio (OR) 1·623 (95% CI 1·319-1·997) on a day of temperature 32°C compared with one of 17°C, the effects being strongest on a lag of 1 day. There was an OR of 1·020 (1·019-1·020) per 1°C increase in temperature above 17°C. The odds of a heat-related AKI episode were similar between AKI stages 1 and 2, but considerably lower for stage 3 events. A 7-day heatwave in July 2021 was associated with a 28·6% increase in AKI counts (95% CI 26·5-30·7).

INTERPRETATION

Heat-related AKI is a growing public health challenge. As even small changes in renal function can affect patient outcomes, susceptible individuals should be advised to take preventive measures whenever hot weather is forecast. Use of an e-alert system allows effects in milder cases that do not require secondary care to also be detected.

FUNDING

National Institute for Health and Care Research (NIHR).

Association between air temperature and risk of hospitalization for genitourinary disorders: An environmental epidemiological study in Lanzhou, China

OBJECTIVES

The aim of this study was to investigate the relationship between air temperature and the risk of hospitalization for genitourinary disorders.

METHODS

Distributed lag non-linear models (DLNM) were used to estimate the association between air temperature and the risk of hospitalization for genitourinary disorders, with subgroup analysis by gender and age to identify the susceptible population of temperature-sensitive genitourinary system diseases.

RESULTS

Low mean temperature (MT) (RR = 2.001, 95% CI: 1.856~2.159), high MT (RR = 2.884, 95% CI: 2.621~3.173) and low diurnal temperature range (DTR) (RR = 1.619, 95% CI: 1.508~1.737) were all associated with the increased risk of hospitalization for genitourinary disorders in the total population analysis, and the high MT effect was stronger than the low MT effect. Subgroup analysis found that high MT was more strongly correlated in male (RR = 2.998, 95% CI: 2.623~3.427) and those <65 years (RR = 3.003, 95% CI: 2.670~3.344), and low DTR was more strongly correlated in female (RR = 1.669, 95% CI: 1.510~1.846) and those <65 years (RR = 1.643, 95% CI: 1.518~1.780).

CONCLUSIONS

The effect of high MT on the risk of hospitalization for genitourinary disorders is more significant than that of low MT. DTR was independently associated with the risk of hospitalization for genitourinary disorders.

Assessment of cold exposure-induced metabolic changes in mice using untargeted metabolomics

Background: Cold exposure (CE) can effectively modulate adipose tissue metabolism and improve metabolic health. Although previous metabolomics studies have primarily focused on analyzing one or two samples from serum, brown adipose tissue (BAT), white adipose tissue (WAT), and liver samples, there is a significant lack of simultaneous analysis of multiple tissues regarding the metabolic changes induced by CE in mice. Therefore, our study aims to investigate the metabolic profiles of the major tissues involved. Methods: A total of 14 male C57BL/6J mice were randomly assigned to two groups: the control group (n = 7) and the CE group (n = 7). Metabolite determination was carried out using gas chromatography-mass spectrometry (GC-MS), and multivariate analysis was employed to identify metabolites exhibiting differential expression between the two groups. Results: In our study, we identified 32 discriminant metabolites in BAT, 17 in WAT, 21 in serum, 7 in the liver, 16 in the spleen, and 26 in the kidney, respectively. Among these metabolites, amino acids, fatty acids, and nucleotides emerged as the most significantly altered compounds. These metabolites were found to be associated with 12 differential metabolic pathways closely related to amino acids, fatty acids, and energy metabolism. Conclusion: Our study may provide valuable insights into the metabolic effects induced by CE, and they have the potential to inspire novel approaches for treating metabolic diseases.

Effects and mechanisms of extremely cold environment on body response after trauma

With the outbreak of the Ukrainian crisis, extremely cold environment warfare has once again become the focus of international attention. People exposed to extremely cold environments may suffer from cold damage, further aggravate trauma, trigger high disability and mortality rates, and even cause serious sequelae. To declare the effects and mechanisms of the extremely cold environment on the body after trauma, this paper reviews, firstly, physiological reaction of human body in an extremely cold environment. Then, the post-traumatic body response in an extremely cold environment was introduced, and finally, the sequelae of trauma in extremely cold environment was further summarized in the paper. The results indicated that extremely cold environment can cause a series of damage to the body, especially the body after trauma. The extremely cold factor is a double-edged sword, showing a favorable and unfavorable side in different aspects. Moreover, in addition to the trauma suffered by the body, the subsequent sequelae such as cognitive dysfunction, anxiety, depression and even post-traumatic stress disorder may also be induced. The paper summarizes the human body's physiological response in an extremely cold environment, and declares the effects and mechanisms of the extremely cold environment on the body after trauma, which may provide a theoretical basis for effectively improving the level of combat trauma treatment in extremely cold regions.