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We aimed to evaluate the association of altitudes with the prevalence of hypertension among residents aged 15 years and above in Tibet, China. Data for 11,407 Tibetan residents from the National Health Services Survey in 2013 were analyzed. Association between altitudes and prevalence of physician-diagnosed hypertension was assessed by two logistic regression models as follows: (i) a base model adjusted for age and gender, and (ii) a full model additionally adjusted for body mass index, education, marital status, area of residence, distance to the nearest medical institute, smoking, drinking, and exercise. Nonlinear relationship between altitudes and prevalence of hypertension was explored by restricted cubic spline analyses. Sensitivity analyses were conducted by restricting to residents of rural and/or nomadic areas. The prevalence of hypertension was estimated to be 37.6%. We found a U-shaped association between altitudes and prevalence of physician-diagnosed hypertension with a turning point at around 3800 m (12,467 ft). For residents living above 3800 m, a 1000 m increase in altitudes was associated with 2.05 (95% confidence interval [CI]: 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 odds ratio (OR) dropped to 1.87 (95% CI: 1.46-2.41). For residents living below 3800 m, a 1000 m increase was associated with 0.29 (95% CI: 0.19-0.44) times less likelihood of having physician-diagnosed hypertension in the full model. Sensitivity analyses among residents in rural and/or nomadic areas showed similar associations. To conclude, altitudes were in a U-shaped association with prevalence of hypertension.

Background: Previous small sample studies suggested that elevated altitudes might be associated with the incidence of cardiovascular diseases. However, it remains uncertain whether high altitudes (over 3000 m above sea level) are related to congenital heart disease. We therefore explored the prevalence of congenital heart disease in a large cohort of students in the world's largest prefecture-level city with the highest altitude., Methods: This cross-sectional study included 84,302 student participants (boys 52.12%, girls 47.88%, with an average age of 10.62 ± 3.33 years). Data were extracted from the screening results among different altitude area schools in Nagqu from June 2016 to August 2017. Students were first screened by performing a physical examination consisting of cardiac auscultations and clinical manifestation screenings. An echocardiography was performed to confirm and identify the subtype of congenital heart disease., Results: The prevalence of congenital heart disease among students in Nagqu, Tibet, was 5.21‰ (439 cases). The most common congenital heart disease type was patent ductus arteriosus, representing 66.3% of congenital heart diseases diagnosed in this study, followed by atrial septal defect and ventricular septal defect, representing 20.3% and 9.1% of congenital heart diseases, respectively. Students living in higher altitudes were significantly more prone to have congenital heart disease than students in locations with lower altitudes. The prevalence of congenital heart disease in girls was found to be higher than that of boys., Conclusions: The correlation between congenital heart disease and increased altitude is noteworthy. This study's results are the first big data epidemiological investigation to confirm that high altitude is a significant environmental risk factor for congenital heart disease, especially patent ductus arteriosus. Furthermore, the results provide additional support to make a diagnostic and treatment plan to prevent congenital heart disease in high altitude areas.