Association Of Altitude Research Articles

Association of Altitude with Mortality among Patients with Hypertension - A Cohort Study

Abstract Background Available evidence falls short in assessing the risk of all-cause mortality and cardiovascular disease (CVD) mortality among individuals with hypertension residing at various altitudes. This study’s objective was to investigate the correlation between residential altitude and the rates of all-cause mortality and CVD mortality among hypertensive patients. Methods This prospective cohort study encompassed 67,275 hypertensive individuals aged 35 years and above in the year 2018. Participants were categorized into four distinct groups based on their residence altitude: those living below 500 meters, between 500 and 1499 meters, 1500 to 2500 meters, and above 2500 meters. The study spanned a mean follow-up duration of 4.78 years. The associations between residential altitude and the risks of all-cause and CVD mortality were analyzed using Cox proportional hazards regression models. Results Among the 67,275 hypertensive patients included in the study (mean age of 63.9 years, with 45.3% being male), 8,768 deaths were recorded, of which 5,666 were attributed to CVD. Following multivariate adjustment, when compared to the group residing at altitudes below 500 meters, the groups living at altitudes of 500-1499 meters, 1500-2500 meters, and above 2500 meters exhibited significantly elevated risks of all-cause mortality [hazard ratio, HR = 1.45 (95% CI: 1.36-1.54), 1.35 (95% CI: 1.36), and 1.41 (95% CI: 1.28-1.54), respectively] and CVD mortality [HR = 1.47 (95% CI: 1.35-1.58), 1.42 (95% CI: 1.33-1.52), and 1.46 (95% CI: 1.31-1.62), respectively]. For each 500-meter increment in altitude, the risk of all-cause and CVD mortality increased by 10% and 11%, respectively. Subgroup analyses and sensitivity assessments consistently supported this association. Conclusions This study’s findings indicate a substantial connection between long-term residential high-altitude exposure and increased risks of all-cause mortality and CVD mortality among individuals with hypertension. Key messages • Increased altitude of residence increases the risk of subsequent all-cause and CVD mortality in hypertensive patients. • This study highlights that relevant guidelines and healthcare providers should consider altitude as an important factor in reducing the burden of hypertension and CVD.

Association of altitude and frailty in Chinese older adults: using a cumulative frailty index model.

The population is aging exponentially and the resulting frailty is becoming increasingly evident. We aimed to explore the association between altitude and frailty, and to identify associated factors for frailty. This is a community-based cross-sectional survey. 1,298 participants aged ≥60 years from three different altitudes were included in the study. To quantify frailty, we constructed a frailty index (FI) and a frailty score (FS). The FI was divided into non-frailty, prefrailty, and frailty. The Odds Ratios and confidence intervals (ORs, 95%CIs) were used to evaluate the association between altitude and FI and FS in multivariate ordinal logistic regression and linear regression. There were 560 (53.1%) participants in the prefrailty and 488 (37.6%) in the frailty group. The FS increased with higher altitude (P for trend <0.001). Multivariate ordinal logistic regression analysis revealed an association between altitude and frailty, OR = 1.91 (95% CI: 1.38-2.64) in mid-high altitude and 2.49 (95% CI:1.40-4.45) in high altitude. The same trend of association was found in the univariate analysis. The FS increased by 1.69 (95% CI: 0.78-2.60) at mid-high altitude and 3.24 (95%CI:1.66-4.81) at high altitude compared to medium altitude. The study indicates that high altitude exposure is an associated factor for frailty in older adults. This association become stronger with higher altitudes. As a result, it is essential to conduct early frailty screening for residents living at high altitudes.

Association of Altitude and Solar Radiation to Understand Coffee Quality

The consumer market has a strong tendency to consume specialty coffees, making it essential to understand the influence of environmental conditions, such as solar radiation and altitude, on coffee quality. This study aimed to analyze the physical and sensory quality of Arabica coffee as a function of different altitudes and incident solar radiation on the coffee tree. The study was carried out in the city of Manhuaçu-MG, Brazil. Three altitudes (950, 1050 and 1150 m above mean sea level) and two sides of coffee exposure to solar radiation (east face: morning sun and west face: afternoon sun) were studied in two post-harvest processing (natural and peeled cherry). Sensory attributes, granulometry and occurrence of coffee defects were evaluated, in order to verify if there was variation in the physical and sensorial characteristics of the coffee. It was found that at an altitude of 1150mamsl, on the exposed face of the plant that received the afternoon sun, there was the formation of better-quality coffee, when compared to the face that received the morning sun. On the other hand, at lower altitudes, coffees from the face of the plant exposed to the morning sun showed a greater association with physical and sensory quality parameters.

Effect of altitude on COVID-19 mortality in Ecuador: an ecological study

BackgroundThe SARS-CoV-2/COVID-19 pandemic has claimed nearly 900,000 lives worldwide and infected more than 27 million people. Researchers worldwide are studying ways to decrease SARS-CoV-2 transmission and COVID-19 related deaths. Several studies found altitude having a negative association with both COVID-19 incidence and deaths. Ecuadorian data was used to explore the relationship between altitude and COVID-19.MethodsThis is an ecological study examining province-level data. To explore a relationship between altitude and COVID-19, this study utilized publicly available COVID-19 data and population statistics. ANOVA, correlation statistics, and a multivariate linear model explored the relationship between different Ecuadorian altitudes against incidence, mortality, and case-fatality rates. Population statistics attributed to COVID-19 were included in the linear model to control for confounding factors.ResultsStatistically significant differences were observed in the regions of Amazónica, Sierra, Costa of Ecuador for incidence, mortality, and case fatality rates, suggesting an association between altitude and SARS-CoV-2 transmission and COVID-19 disease severity (p-value ≤0.05). In univariate analysis, altitude had a negative association to mortality rate with a 1-unit change in altitude resulting in the decrease of 0.006 units in mortality rate (p-value = 0.03). The multiple linear models adjusted for population statistics showed a statistically significant negative association of altitude with mortality rate (p-value = 0.01) with a 1-unit change in altitude resulting in the decrease in mortality rate by 0.015 units. Overall, the model helped in explaining 50% (R2 = 0.4962) of the variance in mortality rate.ConclusionAltitude may have an effect on COVID-19 mortality rates. However, based on our model and R2 value, the relationship between our variables of interest and COVID-19 mortality may be nonlinear. More research is needed to understand why altitude may have a protective effect against COVID-19 mortality and how this may be applicable in a clinical setting.

Mortality Attributed to COVID-19 in High-Altitude Populations

Woolcott, Orison O., and Richard N. Bergman. Mortality attributed to COVID-19 in high-altitude populations. High Alt Med Biol. 21:409-416, 2020. Background: Since partial oxygen pressure decreases as altitude increases, environmental hypoxia could worsen Coronavirus Disease 2019 (COVID-19) patient's hypoxemia. We compared COVID-19 mortality at different altitudes. Methods: Retrospective analysis of population-level data on COVID-19 deaths was conducted in the United States (1,016 counties) and Mexico (567 municipalities). Mixed-model Poisson regression analysis of the association between altitude and COVID-19 mortality was conducted using individual-level data from 40,168 Mexican subjects with COVID-19, adjusting for multiple covariates. Results: Between January 20 and April 13, 2020, mortality rates were higher in U.S. counties located at ≥2,000 m elevation versus those located <1,500 m (12.3 vs. 3.2 per 100,000; p < 0.001). In Mexico, between March 13 and May 13, 2020, mortality rates were higher in municipalities located at ≥2,000 m versus those located <1,500 m (5.3 vs. 3.9 per 100,000; p < 0.001). Among Mexican subjects younger than 65 years, the risk of death was 36% higher in those living at ≥2,000 m versus those living at <1,500 m (adjusted incidence rate ratio [IRR]: 1.36; confidence interval [95% CI], 1.05-1.78; p = 0.022). Among Mexican men, the risk of death was 31% higher at ≥2,000 m versus that at <1,500 m (adjusted IRR: 1.31; 95% CI, 1.03-1.66; p = 0.025). No association between altitude and COVID-19 mortality was found among Mexican women or among Mexican subjects 65 years of age and older. Conclusions: Altitude is associated with COVID-19 mortality in men younger than 65 years.

Maternal exposure to low-to-medium altitude and birth outcomes: evidence from a population-based study in Chinese newborns.

Despite high altitude was implicated in adverse birth outcomes, there remained a paucity of evidence on low-to-medium altitude effect. This study aimed to explore the association of low-to-medium altitude with birth outcomes. A population-based cross-sectional survey was performed using a stratified multistage random sampling method among women with their infants born during 2010-2013 in Northwestern China. Altitude was determined in meters based on the village or community of the mother's living areas. Birth outcomes involved birth weight, gestational age, and small for gestational age (SGA). Generalized linear models were fitted to investigate the association of altitude with birth outcomes. Moreover, the dose-response relationship between altitude and birth outcomes was evaluated with a restricted cubic spline function. A total of 27 801 women with their infants were included. After adjusting for potential confounders, every 100-m increase in the altitude was associated with reduced birth weight by 6.4 (95% CI -8.1, -4.6) g, the slight increase of gestational age by 0.015 (95% CI 0.010, 0.020) week, and an increased risk of SGA birth (odds ratio 1.03, 95% CI 1.02, 1.04). Moreover, there was an inversely linear relationship between altitude and birth weight (P for overall < 0.001 and P for nonlinear = 0.312), and a positive linear relationship between altitude and SGA (P for overall < 0.001 and P for nonlinear = 0.194). However, a nonlinear relationship was observed between altitude and gestational age (P for overall < 0.001 and P for nonlinear = 0.010). The present results suggest that low-to-medium altitude is possibly associated with adverse birth outcomes.

Abstract MP40: U-shaped Association Of Altitude With Prevalence Of Hypertension Among Tibetan Residents

Background: Tibet has a disproportionately higher prevalence of hypertension, compared to other regions of China. This may be related to long-term exposure to the high altitude. The aim of our study is to evaluate associations of altitudes with prevalence of hypertension among residents aged 15 years and older in Tibet, China. Method: A total of 11,407 Tibet residents in the 5 th National Health Services Survey (NHSS) in 2013-2015 were included in this study. Physician diagnosed hypertension was determined based on self-report. County level altitude was identified and assigned to all residents in a county. Association between altitude and hypertension prevalence was assessed by two logistic regression models: model 1 adjusted for age and gender, and model 2 additionally adjusted for marital status, education, smoking, drinking, exercise, distance to a medical institute, area of residency, and body mass index (BMI). Non-linear relationship between altitude and prevalence of hypertension was explored by restricted cubic spline analyses. Sensitivity analysis were performed by restricting residents in rural and/or nomadic areas. Result: The prevalence of self-reported hypertension is 15.7%, the medication adherence rate is 14%, and the control rate is 10.3%. Compared to residents without physician diagnosed hypertension, those with hypertension were closer to a hospital, older, having lower education level, and less likely to be a smoker or live in an urban area. Altitude showed a U shape relationship with the prevalence of hypertension with a turning point at around 3,800 meters. For residents living more than 3,800 meters above sea level, a 1,000 meters increase in altitude was associated with 2.05 (95% confidence interval: 1.62-2.61) times higher odds of having physician diagnosed hypertension, after adjusting for age and gender. When further controlling for all covariates, the OR dropped to 1.87 (1.46-2.41) but still significant. For residents living below the altitude of 3,800 meters, 1000 meters’ increase was associated 0.55 (95% CI: 0.33-0.92) less likelihood of having physician diagnosed hypertension. Conclusion: The burden of self-reported hypertension was high among Tibet residents. Altitude was in a U-shaped association with the prevalence of hypertension with a turning point at around 3,800 meters.

Pollination Mechanisms are Driving Orchid Distribution in Space

Understanding the abundance and distribution patterns of species at large spatial scales is one of the goals of biogeography and macroecology, as it helps researchers and authorities in designing conservation measures for endangered species. Orchids, one of the most endangered groups of plants, have a complicated system of pollination mechanisms. Their survival strongly depends on pollination success, which then determines their presence and distribution in space. Here we concentrate on how pollination mechanisms (presence/absence of nectar) are associated with orchid species density and mean niche breadth along an altitudinal gradient in six different phytogeographical regions in the Czech Republic. We found differences between these regions in terms of orchid species numbers and density. The trend (hump-shaped curve) in species density of nectarless and nectariferous orchids were very similar in all phytogeographical regions, peaking between 300–900 m. The trend strongly depends on habitat cover and pollinator availability. In general, the most specialist species of orchids were found from low to middle altitudes. The association of altitude with the richness of orchid flora is much stronger than that with the biogeography. Climate change is a factor that should not be neglected, as it may affect the presence/absence of many species in the future.

The importance of altitude and aspect for breeding Whinchats Saxicola rubetra in the uplands: limitations of the uplands as a refuge for a declining, formerly widespread species?

Capsule The likelihood of an area being occupied by breeding Whinchats was inversely related to altitude, and areas with south- and east-facing aspects were favoured over those with north- and west-facing aspects. Aims To identify habitat features and physical attributes of Whinchat territories in upland areas of the UK. Methods Comparison of habitat features and physical attributes measured at random points within territories and > 100 m from a territory in an area with a relatively high breeding density were used to identify factors associated with Whinchat occurrence in upland Scotland. Further data were extracted from recent independent surveys conducted elsewhere in upland Britain. Results Within a favoured habitat (young sparse shrubs and developing ground vegetation) in the main study site, the probability of an area with south- and east-facing aspects being occupied by breeding Whinchats exceeded 80% below 300 m asl and declined linearly to less than 20% above 500 m. For areas with north- and west-facing aspects, the probability of occupancy at 300 m was 40% and close to zero at 500 m. Territory size increased with altitude. Data from elsewhere in upland Britain supported an association of altitude and aspect with Whinchat territories but suggested that such environmental limitations differed between regions. Conclusion Within marginal uplands, Whinchats could be constrained at their lower altitudinal limit by intensive agricultural land-use and at their upper altitudinal limit by environmental restrictions on their breeding biology. Such limitations need to be considered if such areas are to continue to support viable populations of a declining and formerly widespread species.