Cold spells linked with respiratory disease hospitalization, length of hospital stay, and hospital expenses: Exploring cumulative and harvesting effects
“…This may reflect the regional differences in the impact of cold spells due to geographic and climatic conditions, indicating that cold spells also have a significant impact on the health of residents in cities with long cold periods. The cumulative lag effect in our study lasted for 2–3 weeks, consistent with previous studies [ 11 , 15 ]. Experiments also demonstrated that the human body requires approximately 2–3 weeks to adjust to cold conditions [ 34 ].…”
Section: Discussionsupporting
confidence: 92%
“…These factors negatively impacted non-accidental deaths within the population, and the confidence intervals for the effect estimates widen as the definition of cold spells became stricter. Based on these preliminary results and referencing previous studies, we selected the 7th-D3 definition, which had the smallest GCV, as the optimal definition of the cold spell [ 15 ], [ 19 ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Within this study, cold spells were defined according to previous studies as a daily mean temperature below the 5th, 7.5th, or 10th percentile lasting at least 2 to 4 consecutive days [ 15 ].…”
Section: Methodsmentioning
confidence: 99%
“…Since the effects of a cold spell could last up to 2–3 weeks, we set the maximum lag at 21 days to study the lagged effects of cold spells on non-accidental mortality [ 21 ]. Additionally, we accounted for the influence of relative humidity and PM 2.5 on pollutant concentrations in Xining by employing natural spline (ns) curves with three degrees of freedom (df) [ 15 , 22 ], considering previous research findings and the prolonged heating period [ 23 ], [ 24 ]. where E(Y) represents the expected daily number of deaths; α is the intercept; cb(CS) is the cross-basis function for cold spells, used to examine the lag effects; stratum is a time-stratification variable for controlling the influence of long-term trends, seasonal variations, and other temporal factors; ns(rh, 3) is the natural cubic spline of relative humidity with 3 degrees of freedom; ns(PM 2.5 , 3) is the natural cubic spline of PM2.5 with 3 degrees of freedom; vacation is a binary variable used to control for Chinese holidays.…”
Objective
Amidst climate change, extensive research has centered on the health impacts of heatwaves, yet the consequences of cold spells, particularly in cooler, higher-altitude regions, remain under-explored.
Methods
Analyzing climatic data and non-accidental mortality in Xining, China’s second-highest provincial capital, from 2016 to 2020, this study defines cold spells as daily mean temperatures below the 10th, 7.5th, or 5th percentiles for 2–4 consecutive days. A time-stratified case-crossover approach and distributional lag nonlinear modeling were used to assess the link between cold spells and mortality, calculating attributable fractions (AFs) and numbers (ANs) of deaths. The study also examined the impact of cold spells over different periods and analyzed the value of a statistical life (VSL) loss in 2018, a year with frequent cold spells. Stratified analyses by sex, age, and education level were conducted.
Results
A significant association was found between cold spells and non-accidental mortality, with a relative risk of 1.548 (95% CI: 1.300, 1.845). The AF was 33.48%, with an AN of 9,196 deaths during the study’s cold period. A declining trend in mortality risk was observed from 2019–2020. The 2018 VSL was approximately 2.875 billion CNY, about 1.75% of Xining’s GDP. Higher risks were noted among males, individuals aged ≥ 65, and those with lower education levels.
Conclusion
The findings underscore the vulnerability and economic losses of high-altitude cities to cold spells. Implementing interventions such as improved heating, educational programs, and community support is vital for mitigating these adverse health effects.
“…This may reflect the regional differences in the impact of cold spells due to geographic and climatic conditions, indicating that cold spells also have a significant impact on the health of residents in cities with long cold periods. The cumulative lag effect in our study lasted for 2–3 weeks, consistent with previous studies [ 11 , 15 ]. Experiments also demonstrated that the human body requires approximately 2–3 weeks to adjust to cold conditions [ 34 ].…”
Section: Discussionsupporting
confidence: 92%
“…These factors negatively impacted non-accidental deaths within the population, and the confidence intervals for the effect estimates widen as the definition of cold spells became stricter. Based on these preliminary results and referencing previous studies, we selected the 7th-D3 definition, which had the smallest GCV, as the optimal definition of the cold spell [ 15 ], [ 19 ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Within this study, cold spells were defined according to previous studies as a daily mean temperature below the 5th, 7.5th, or 10th percentile lasting at least 2 to 4 consecutive days [ 15 ].…”
Section: Methodsmentioning
confidence: 99%
“…Since the effects of a cold spell could last up to 2–3 weeks, we set the maximum lag at 21 days to study the lagged effects of cold spells on non-accidental mortality [ 21 ]. Additionally, we accounted for the influence of relative humidity and PM 2.5 on pollutant concentrations in Xining by employing natural spline (ns) curves with three degrees of freedom (df) [ 15 , 22 ], considering previous research findings and the prolonged heating period [ 23 ], [ 24 ]. where E(Y) represents the expected daily number of deaths; α is the intercept; cb(CS) is the cross-basis function for cold spells, used to examine the lag effects; stratum is a time-stratification variable for controlling the influence of long-term trends, seasonal variations, and other temporal factors; ns(rh, 3) is the natural cubic spline of relative humidity with 3 degrees of freedom; ns(PM 2.5 , 3) is the natural cubic spline of PM2.5 with 3 degrees of freedom; vacation is a binary variable used to control for Chinese holidays.…”
Objective
Amidst climate change, extensive research has centered on the health impacts of heatwaves, yet the consequences of cold spells, particularly in cooler, higher-altitude regions, remain under-explored.
Methods
Analyzing climatic data and non-accidental mortality in Xining, China’s second-highest provincial capital, from 2016 to 2020, this study defines cold spells as daily mean temperatures below the 10th, 7.5th, or 5th percentiles for 2–4 consecutive days. A time-stratified case-crossover approach and distributional lag nonlinear modeling were used to assess the link between cold spells and mortality, calculating attributable fractions (AFs) and numbers (ANs) of deaths. The study also examined the impact of cold spells over different periods and analyzed the value of a statistical life (VSL) loss in 2018, a year with frequent cold spells. Stratified analyses by sex, age, and education level were conducted.
Results
A significant association was found between cold spells and non-accidental mortality, with a relative risk of 1.548 (95% CI: 1.300, 1.845). The AF was 33.48%, with an AN of 9,196 deaths during the study’s cold period. A declining trend in mortality risk was observed from 2019–2020. The 2018 VSL was approximately 2.875 billion CNY, about 1.75% of Xining’s GDP. Higher risks were noted among males, individuals aged ≥ 65, and those with lower education levels.
Conclusion
The findings underscore the vulnerability and economic losses of high-altitude cities to cold spells. Implementing interventions such as improved heating, educational programs, and community support is vital for mitigating these adverse health effects.
“…Within this study, cold waves were characterised as daily average temperatures falling below specific percentiles (2.5th, 5th, 7.5th, or 10th) and persisting for a minimum of 2 to 4 consecutive days, based on previous studies [ 22 , 23 ]. For instance, 7.5th -2D denotes a cold wave defined as at least 2 consecutive days with daily apparent temperature at or below the 7.5th percentile.…”
Background
Extreme weather events like heatwaves and fine particulate matter (PM2.5) have a synergistic effect on mortality, but research on the synergistic effect of cold waves and PM2.5 on outpatient visits for respiratory disease, especially at high altitudes in climate change-sensitive areas, is lacking.
Methods
we collected time-series data on meteorological, air pollution, and outpatient visits for respiratory disease in Xining. We examined the associations between cold waves, PM2.5, and outpatient visits for respiratory disease using a time-stratified case-crossover approach and distributional lag nonlinear modeling. Our analysis also calculated the relative excess odds due to interaction (REOI), proportion attributable to interaction (AP), and synergy index (S). We additionally analyzed cold waves over time to verify climate change.
Results
Under different definitions of cold waves, the odds ratio for the correlation between cold waves and outpatient visits for respiratory disease ranged from 0.95 (95% CI: 0.86, 1.05) to 1.58 (1.47, 1.70). Exposure to PM2.5 was significantly associated with an increase in outpatient visits for respiratory disease. We found that cold waves can synergize with PM2.5 to increase outpatient visits for respiratory disease (REOI > 0, AP > 0, S > 1), decreasing with stricter definitions of cold waves and longer durations. Cold waves’ independent effect decreased over time, but their interaction effect persisted. From 8.1 to 21.8% of outpatient visits were due to cold waves and high-level PM2.5. People aged 0–14 and ≥ 65 were more susceptible to cold waves and PM2.5, with a significant interaction for those aged 15–64 and ≥ 65.
Conclusion
Our study fills the gap on how extreme weather and PM2.5 synergistically affect respiratory disease outpatient visits in high-altitude regions. The synergy of cold waves and PM2.5 increases outpatient visits for respiratory disease, especially in the elderly. Cold wave warnings and PM2.5 reduction have major public health benefits.
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