Association of altitude with all-cause and cardiovascular mortality among patients with hypertension: a cohort study in Southwest China

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BackgroundAvailable evidence falls short in assessing the risk of long-term outcomes among individuals with hypertension residing at various altitudes. We aimed to investigate the association between residential altitude and the risk of all-cause and cardiovascular disease (CVD) mortality among hypertensive patients.MethodsThis cohort study encompassed 67,275 hypertensive patients aged ≥35 years who participated in China’s Basic Public Health Service Program in 2018. Participants were categorized into four groups based on their residence altitude: <500 m, 500-1,499 m, 1,500-2,500 m, and > 2,500 m. The associations between residential altitude and the risks of all-cause and CVD mortality were analyzed using Cox proportional hazards regression models. The dose-response relationship was performed by the restricted cubic spline with multivariable adjusted models.ResultsAmong the 67,275 hypertensive patients included in the study (mean age of 63.9 years, with 45.3% 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 < 500 m, the groups living at altitudes of 500-1,499 m, 1500-2,500 m, and > 2,500 m exhibited significantly risks of all-cause mortality [HR = 1.45 (95% CI: 1.36–1.54), 1.35 (95% CI: 1.28–1.43), 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]. The restricted cubic spline curves revealed a nonlinear relationship between residential altitude and all-cause and CVD mortality. The risk of mortality was higher among participants with poorly controlled blood pressure, aged 65 years and above, and living in rural areas.ConclusionsThis study demonstrated a significant association between long-term residential high-altitude exposure and increased risks of all-cause and CVD mortality among hypertension patients. The implications of the findings call for a prioritization of public health resource allocation and early intervention efforts, especially for those living at high altitudes and in low-income areas where hypertension is prevalent.