Relationship between hypertension and geographic altitude: a cross-sectional survey among residents in Tibet

Clinical characteristics and the prognosis of diabetic foot in Tibet: A single center, retrospective study

The objective of this study was to explore the clinical characteristics and prognosis of diabetic foot in hospitalized patients with diabetes in Tibet. To achieve that, patients hospitalized in People's Hospital of Tibet Autonomous Region and diagnosed with diabetic foot ulcer (DFU) from January 1, 2016 to December 31, 2020 were enrolled in the study, and DFU cases of Peking University First Hospital were collected as control group. Analysis and comparison of clinical characteristics of DFU in plateau and plain areas were conducted. Normal distribution data or non-normal distribution data between groups were analyzed by t-test analysis or the nonparametric Mann-Whitney U test, and categorical variants were compared by Chi-square of Pearson. A total of 54 DFU cases were enrolled in the study in the People's Hospital of Tibet Autonomous Region (Tibet group for short). Males accounted for 83.3% (45 cases) in Tibet group, which was higher than that of Peking University First Hospital (Beijing group for short), which accounted for 67.0%. Compared with the DFU patients in the Beijing group, the Tibet group was younger (58.11 ± 12.25 years vs 64.18 ± 11.37 years, P < 0.05), with a shorter disease duration (7.00 years vs 12.00 years, P < 0.05). In contrast, alcohol consumption was higher in the Tibet group (44.4 vs 27.4%, P < 0.05), and the number of patients with smoking habit was higher in the Beijing group (29.6 vs 43.7%, P < 0.05). The Tibet group had higher HbA1c (10.2 vs 8.7%, P < 0.05) and lower DFU proportion (22.2 vs 44.2%, P < 0.05). There was no statistically significant difference in the proportion of moderate to severe infections between the two groups (58.5 vs 59.6%, P = 0.887). Leukocytes (6.75 × 109/L vs 8.72 × 109/L, P < 0.05) and neutrophils (4.07 × 109/L vs 6.26 × 109/L, P < 0.05) in Tibet group were lower. Although the DFU amputation rate in the Tibet group was lower than that in the Beijing group (9.3 vs 29.8%, P < 0.05), there was no statistically significant difference between the two groups in terms of treatment cost, hospital stay, and mortality. In conclusion, patients with DFU in Tibet had a smaller age, shorter duration of diabetes, and more male predominance. The proportions of gangrene and amputation were lower in Tibet, with gangrene accounting for 80% of all amputees.

Prevalence of hypertension in adults living at altitude in Latin America and the Caribbean: A systematic review and meta-analysis

OBJECTIVE

The objective of this systematic review and meta-analysis was to assess the prevalence of hypertension in populations living at altitude in Latin America and the Caribbean.

METHODS

We conducted a systematic search from January 1, 2000 to January 10, 2023 in Web of Science (WoS)/Core Collection, WoS/Medline, WoS/Scielo, Scopus, PubMed and Embase databases. We included studies that assessed the prevalence of hypertension in altitude populations (>1500 m.a.s.l.) and these were meta-analyzed using a random-effects model. To assess the sources of heterogeneity, we performed subgroup and meta-regression analyses.

RESULTS

Thirty cross-sectional studies (117 406 participants) met the inclusion criteria. Studies used different cut-off points. The prevalence of hypertension in the studies that considered the cut-off point of ≥ 140/90 mmHg in the general population was 19.1%, ≥ 130/85 mmHg was 13.1%, and ≥ 130/80 mmHg was 43.4%. There was a tendency for the prevalence of hypertension to be higher in men. In meta-regression analyses, no association was found between altitude, mean age, year of publication, risk of bias and prevalence of hypertension.

CONCLUSION

The prevalence of hypertension in the altitude population of Latin America and the Caribbean is lower than that reported in populations living at sea level and lower than other altitude populations such as Tibetans.

PROSPERO

CRD42021275229.

Factors Affecting Carotid Artery Stenosis in the Elderly Living at High Altitudes

BACKGROUND

Factors affecting carotid artery stenosis have been generally investigated. However, considering the protective effect of altitude, studies on elderly individuals at high altitudes are few. Our aim is to investigate the systematic adaptive changes caused by high-altitude exposure through the causes of carotid artery stenosis.

MATERIALS AND METHODS

Carotid Doppler ultrasound was performed on 250 patients over the age of 50 years. The patients' age, gender, height, weight, smoking history, place of residence, and presence of comorbidities were questioned. Those with diabetes, hypertension, hyperlipidemia, and coronary disease were excluded from the study. Those who did not reside at high altitudes were excluded from the study. One hundred and thirty-five patients were included in the study. Carotid artery Doppler findings and biochemical parameters were recorded. Factors affecting stenosis in the carotid arteries were compared.

RESULTS

In our study, the factors affecting carotid stenosis were determined to be age, gender, presence of plaque, plaque type, and mean carotid intima-media thickness (CIMT). The mean CIMT of the patients was calculated as 0.71±0.14 mm. The mean CIMT measurement level was significantly higher in patients with plaque in the carotid artery (p<0.05). According to receiver operating characteristic curves, CIMT values higher than 0.72 mm increase plaque and stenosis formation in the common carotid artery (CCA) and internal carotid artery (ICA) in elderly people living at high altitudes (p<0.05, area under the curve [AUC]: 0.71-0.83).

CONCLUSIONS

The most important factors affecting carotid stenosis in individuals living at high altitudes are age, gender, CIMT, plaque, and plaque type. When soft plaques were detected, the risk of stenosis was found to be higher than in calcific plaques. Additionally, the number of factors affecting stenosis was greater on the left (ICA). This suggests that the left carotid system is more vulnerable. It can be said that in elderly individuals living at high altitudes, a CIMT higher than 0.72 mm is a cutoff value in the presence of plaque and stenosis in the carotid arteries.

Recent public health concerns of the high-altitude tribal population of Lahaul and Spiti, Himachal Pradesh

Objective

India has a tribal population of 8.6%. Health concerns of the high-altitude tribal population in India play a vital role in overall socio-economic development and health transformation of the country. Therefore, the aim of this study was to determine the current health problems among the tribal population of Lahaul and Spiti district of Himachal Pradesh.

Material and Methods

The study area encompasses one regional hospital (RH) in Keylong (the district headquarters), three community health centers (CHCs), and 16 primary health care centers (PHCs). In addition, the district has 37 sub-centers (SCs) and 21 Ayurveda dispensaries to serve the district. The data for this study were gathered over a 4-year period from records of daily out-patient department registration from the various health centers (RH, CHCs, and PHCs) from 2017 to 2020.

Results

In terms of communicable diseases, the population in the concerned region was more likely to have acute respiratory infection, enteric fever, tuberculosis, and typhoid. Hypertension, asthma, bronchitis, and diabetes mellitus type II were determined to be the most common non-communicable diseases.

Conclusion

Acute respiratory disease, hypertension, diarrhea, accidental injuries, and eye problems were shown to be prevalent in the study area. The population's position in relation to these five diseases indicates the community's sensitivity to a variety of common conditions. There is a need to review the needs and priorities of the concerned population and create goals and targets to meet those needs using validated public health measures.

The association between altitude and the prevalence of hypertension among permanent highlanders

Hypertension (HTN) is a growing contributor to the global disease burden, and it is prevalent among people living at high altitudes (H-ALTs). This study aimed to explore the relationship between altitude and the prevalence of HTN among inhabitants living at H-ALTs. We searched electronic databases, including PubMed, Embase, and Web of Science, up to April 30, 2022. The quality of included studies was assessed using the Joanna Briggs Institute (JBI) checklist for prevalence studies. A total of 1273 articles were screened, and 32 studies (86,487 participants) were eligible for further analyses. The pooled prevalence among highlanders was 28.7%. General additive model (GAM)-based meta-regression analysis was conducted to explore the association between altitude and the prevalence of HTN. A curve-shaped line was found between altitude and the prevalence of HTN (β = 0.998, p = 0.039) after adjusting for factors including publication year, sample size, age, sex, ethnic group, body mass index (BMI), smoking and alcohol consumption. The turning point was observed at 3300 m. The predictive parameter indicated that the smoothness and goodness of model fit were good (GCV = 0.014, R² = 0.60, respectively). The findings may provide clues for further mechanistic studies that can improve HTN prevention among highlanders.

Prevalence, Management, and Associated Factors of Obesity, Hypertension, and Diabetes in Tibetan Population Compared with China Overall

Tibetans’ life expectancy lags behind China’s average. Obesity and noncommunicable diseases (NCDs) contribute to health disparity, but NCD patterns among Tibetans are unknown. To examine the prevalence, management, and associated factors for obesity, hypertension, and diabetes among Tibetans, compared with China’s average, we systematically searched PubMed and China National Knowledge Infrastructure databases for studies between January 2010 and April 2021. Thirty-nine studies were included for systematic review, among thirty-seven that qualified for meta-analysis, with 115,403 participants. Pooled prevalence was 47.9% (95% CI 38.0–57.8) for overweight/obesity among adults (BMI ≥ 24 kg/m²) and 15.4% (13.7–17.2) among children using Chinese criteria, which are lower than the national rates of 51.2% and 19.0%, respectively. The estimate for hypertension (31.4% [27.1–35.7]) exceeded China’s average (27.5%), while diabetes (7.5% [5.2–9.8]) was lower than average (11.9%). Men had a higher prevalence of the three conditions than women. Residents in urban areas, rural areas, and Buddhist institutes had monotonically decreased prevalence in hypertension and diabetes. Awareness, treatment, and control rates for hypertension and diabetes were lower than China’s average. Urban residence and high altitude were consistent risk factors for hypertension. Limited studies investigated factors for diabetes, yet none exist for obesity. Tibetans have high burdens of obesity and hypertension. Representative and longitudinal studies are needed for tailored interventions. There are considerable variations in study design, study sample selection, and data-analysis methods, as well as estimates of reviewed studies.

Association between Altitude and the Framingham Risk Score: A Cross-Sectional Study in the Peruvian Adult Population

To determine the association between altitude and the Framingham risk score in the Peruvian population, we performed a cross-sectional analytical study of data collected by the 2017–2018 Food and Nutrition Surveillance by Life Stages survey. The outcome of this study was the Framingham 10-year cardiovascular disease event risk prediction, which is composed of six modifiable and non-modifiable coronary risk factors. A generalized linear model (GLM) of the gamma family and log link function was used to report the crude and adjusted β coefficients. Several sensitivity analyses were performed to assess the association of interest. Data from a total of 833 surveyed participants were included. After adjusting for educational level, poverty level, alcohol consumption, physical activity level, the presence of any limitation, obesity, and area of residence, it was observed that altitude ≥ 2500 m above sea level (β = −0.42 [95% CI: −0.69 to −0.16]) was negatively and significantly associated with a decrease in the Framingham 10-year risk score. High altitude was significantly and negatively associated with Framingham 10-year risk scores. Our results will allow prevention strategies considering modifiable risk factors to avoid the development of cardiovascular diseases, especially in people living at low altitudes.

Residential elevation and its effects on hypertension incidence among older adults living at low altitudes: a prospective cohort study

Background

Research on the relationship between residential altitude and hypertension incidence has been inconclusive. Evidence at low altitudes (i.e., <1,500 m) is scarce, let alone in older adults, a population segment with the highest hypertension prevalence. Thus, the objective of this study is to determine whether hypertension risk may be affected by altitude in older adults living at low altitudes.

Methods

This prospective cohort study collected data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS). We selected 6,548 older adults (≥65 years) without hypertension at baseline (2008) and assessed events by the follow-up surveys done in 2011, 2014, and 2018 waves. The mean altitude of 613 residential units (county or district) in which the participants resided was extracted from the Digital Elevation Model (DEM) of the National Aeronautics and Space Administration (NASA) and was accurate to within 30 m. The Cox regression model with penalized splines examined the linear or nonlinear link between altitude and hypertension. A random-effects Cox regression model was used to explore the linear association between altitude and hypertension.

Results

The overall rate of incident hypertension was 8.6 per 100-person years. The median altitude was 130.0 m (interquartile range [IQR] = 315.5 m). We observed that the exposure–response association between altitude and hypertension incidence was not linear. The shape of the exposure–response curve showed that three change points existed. Hypertension risk increased from the lowest to the first change point (247.1 m) and slightly fluctuated until the last change point (633.9 m). The risk decreased above the last change point. According to the categories stratified by the change points, altitude was only significantly associated with hypertension risk (hazard ratio [HR] = 1.003; 95% confidence interval [CI] = 1.002–1.005) under the first change point (247.1 m) after adjusting for related covariates.

Conclusion

Our study found that the association between altitude and hypertension risk might not be linear. We hope the further study can be conducted to confirm the generality of our findings.

Supplementary information

The online version contains supplementary material available at https://doi.org/10.1265/ehpm.22-00001.

Phenotypic differences between highlanders and lowlanders in Papua New Guinea

OBJECTIVES

Altitude is one of the most demanding environmental pressures for human populations. Highlanders from Asia, America and Africa have been shown to exhibit different biological adaptations, but Oceanian populations remain understudied [Woolcock et al., 1972; Cotes et al., 1974; Senn et al., 2010]. We tested the hypothesis that highlanders phenotypically differ from lowlanders in Papua New Guinea, as a result of inhabiting the highest mountains in Oceania for at least 20,000 years.

MATERIALS AND METHODS

We collected data for 13 different phenotypes related to altitude for 162 Papua New Guineans living at high altitude (Mont Wilhelm, 2,300-2,700 m above sea level (a.s.l.) and low altitude (Daru, <100m a.s.l.). Multilinear regressions were performed to detect differences between highlanders and lowlanders for phenotypic measurements related to body proportions, pulmonary function, and the circulatory system.

RESULTS

Six phenotypes were significantly different between Papua New Guinean highlanders and lowlanders. Highlanders show shorter height (p-value = 0.001), smaller waist circumference (p-value = 0.002), larger Forced Vital Capacity (FVC) (p-value = 0.008), larger maximal (p-value = 3.20e -4) and minimal chest depth (p-value = 2.37e -5) and higher haemoglobin concentration (p-value = 3.36e -4).

DISCUSSION

Our study reports specific phenotypes in Papua New Guinean highlanders potentially related to altitude adaptation. Similar to other human groups adapted to high altitude, the evolutionary history of Papua New Guineans appears to have also followed an adaptive biological strategy for altitude.

Impact of High Altitude on Cardiovascular Health: Current Perspectives

Globally, about 400 million people reside at terrestrial altitudes above 1500 m, and more than 100 million lowlanders visit mountainous areas above 2500 m annually. The interactions between the low barometric pressure and partial pressure of O2, climate, individual genetic, lifestyle and socio-economic factors, as well as adaptation and acclimatization processes at high elevations are extremely complex. It is challenging to decipher the effects of these myriad factors on the cardiovascular health in high altitude residents, and even more so in those ascending to high altitudes with or without preexisting diseases. This review aims to interpret epidemiological observations in high-altitude populations; present and discuss cardiovascular responses to acute and subacute high-altitude exposure in general and more specifically in people with preexisting cardiovascular diseases; the relations between cardiovascular pathologies and neurodegenerative diseases at altitude; the effects of high-altitude exercise; and the putative cardioprotective mechanisms of hypobaric hypoxia.

Coverage and effectiveness of hypertension screening in different altitudes of Tibet autonomous region

BACKGROUND

Tibet is an autonomous region in China located around an average altitude of 4500 m above sea level. Since 2012 the local government of Tibet has been providing free physical examinations, including screening for hypertension. However, the coverage and effectiveness of this free program have not been uncovered. This study aims to assess the coverage and effectiveness of hypertension screening and management program in 3 altitude levels of Tibet, and also the determinants of the success of the screening program.

METHODS

A stratified cluster survey was conducted among 1636 residents aged 18 years or over in three different altitude areas in Tibet. We adjusted for age and sex based on national census data and used weighted logistic regression models to find factors associated with hypertension screening.

RESULTS

The coverage of the hypertension screening program evaluated by participation rate in the previous screening was 94.9%, while 24.7% (95% CI: 22.1-27.3%) of them were diagnosed with hypertension. Females and alcohol drinkers were more likely to be screened. Among those diagnosed with hypertension, 28.7% had it under control. High altitude areas had a high proportion of controlled hypertension. The overall rate of controlled hypertension in high, moderate and low altitude areas was 35.1% (95% CI: 24.8-45.3%), 32.7% (95% CI: 22.2-43.2%) and 23.7% (95% CI: 14.7-32.6%), respectively. Younger aged persons were more likely to have better control of their hypertension.

CONCLUSIONS

The coverage of hypertension screening in Tibet was high, especially in the low altitude areas. However, the effectiveness of hypertension control was low, indicating a need to implement the treatment adherence routines into the current screening interventions.