Hypertension and altitude in community-dwelling older adults: an epidemiological study in northwest China.

摘要

OBJECTIVES: Hypertension is a major risk factor for cardiovascular and cerebrovascular diseases, and a relationship between altitude and hypertension has been demonstrated. To better characterise this relationship, this study investigated the prevalence of hypertension and its association with altitude in community-dwelling older adults living at different altitudes in Xinjiang, northwest China. DESIGN: A cross-sectional study. SETTING: Xinjiang, China. PARTICIPANTS: 50 778 community-dwelling older adults residing at varying altitudes across Xinjiang. MEASURES: A multistage stratified sampling method was used to conduct an epidemiological survey from January 2019 to December 2019 among 50 778 community-dwelling older adults aged ≥60 years who were long-term residents of Kashgar (1289 m), Hami (738 m) and Turpan (35 m), Xinjiang. Logistic regression analysis was conducted to evaluate the association between altitude and hypertension risk. RESULTS: Mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) showed significant variations (both p<0.001) across Kashgar, Hami and Turpan at different altitudes: Kashgar (SBP: 133.15±19.644 mm Hg, DBP: 76.6±11.363 mm Hg), Hami (SBP: 136.68±19.617 mm Hg, DBP: 77.25±11.808 mm Hg) and Turpan (SBP: 135.44±21.101 mm Hg, DBP: 74.87±12.785 mm Hg). Statistically significant differences in the distributions of both SBP and DBP were observed across different altitudes for both males and females (all p<0.001). The differences in the distributions of SBP and DBP at different altitudes were statistically significant in all age groups, except for ≥90 years (all p<0.001). Moreover, the differences in SBP and DBP in older individuals living at the three altitudes were statistically significant (all p<0.001) regardless of smoking status, alcohol consumption, diabetes, education level or body mass index. The hypertension prevalence rates were 40.5%, 49.5% and 54.5% in Kashgar, Hami and Turpan, respectively (p<0.001). After adjustment for sex, age group, education level, smoking, alcohol consumption, BMI, diabetes, HR, SCr, blood urea nitrogen and dyslipidaemia, the risk of hypertension was increased in Hami (OR = 1.55, 95% CI 1.45 to 1.66, p<0.001) and Turpan (OR=1.80, 95% CI 1.71 to 1.88, p<0.001) compared with that in Kashgar. CONCLUSIONS: In community-dwelling older adults residing in lowland to mid-elevation zones (35-1289 m) of Xinjiang, the prevalence and risk of hypertension were found to be inversely associated with residential altitude. These findings may reflect an environmental gradient effect specific to mid-to-low altitude settings, and their generalisability may be limited to populations at higher altitudes (>1500 m) or regions with distinct ethnic, genetic or healthcare backgrounds. Furthermore, it should be emphasised that this association likely reflects altitude-related environmental factors rather than direct physiological effects of hypoxia. Additional studies are warranted to further elucidate these complex relationships.