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Geographic variations and potential macro-environmental exposure of hypertension: from the China hypertension survey.

OBJECTIVES
The study aimed to investigate the spatial variation of hypertension (HTN) and the associations between the risk of HTN and altitude, longitude, latitude in Chinese population.


METHODS
The newest China Hypertension Survey (CHS) study, which used a nationally representative sample, was conducted between 2012 and 2015. A total of 451 755 participants aged at least 18 years from 262 county-level regions in 31 provinces were analyzed to explore the geographical variations of HTN prevalence at county-level. A total of 444 375 participants were included in two-level logistic regression model to examine the association between HTN risk and exposure to altitude, longitude, and latitude after adjusting for potential confounding variables at individual level.


RESULTS
The findings of spatial analysis indicated that there were remarkably high and low HTN prevalence zones. High HTN prevalence zones extended from parts of the southeast to northern China and the northeast. The risk of HTN increased with increasing longitude, with adjusted odds ratios (aORs, 95% confidence interval [CI]) of 2.08 (1.04--4.18), 2.21 (1.15--4.22), 2.54 (1.31--4.93), 2.59 (1.32--5.08), and 2.81 (1.12--7.08) for longitudes of 90-100°E, 100-110°E, 110-120°E, 120-130°E, and at least 130°E, respectively, with a significant dose--response relationship that HTN risks increase as longitude rises from 90°E to ≥130°E(Ptrend <0.001), compared with the longitude group of less than 80°E, consistent with the conclusion that geographical variations of high HTN prevalence zones by spatial analysis.


CONCLUSION
The findings of remarkably high HTN prevalence zones modified previous understandings about the regional difference of HTN distribution, and provide an important basis for future efforts to prevent and control HTN in different regions of China.