Abstract P226: Changes of Blood Pressure and Urinary Sodium Over 18 Years in Rural China: Results From the INTERMAP China Prospective Study
Research paper by
Li YanEllison CarterYu FuGaoqiang XieWuxiang XieFrank KellyPaul ElliottXudong YangMajid EzzatiJill BaumgartnerLiancheng ZhaoYangfeng WuQueenie Chan1King’s College London, London, United Kingdom2Colorado State Univ, Fort Collins, CO3Tsinghua Univ, Beijin, China4Peking Univ Clinical Rsch Institute, Beijing, China5Imperial College London, London, United Kingdom6Tsinghua Univ, Beijing, China7McGill Univ, Montreal, Canada8Peking Union Med College & Chinese Academy of Med Sciences, Beijing, China
Background: Tremendous dietary pattern changes could be a driver of the increasing burden of high blood pressure (BP) in developing countries. However, data on nutrition transitions and associated BP changes are scarce.
Objective: To explore BP changes and sodium (Na) consumption over 18 years in China.
Methods: International Collaborative Study of Macro-/Micro-nutrients and Blood Pressure (INTERMAP) enrolled 839 men and women aged 40-59 years from three geographically diverse regions (Beijing, Shanxi in the north and Guangxi in the south) in 1997. INTERMAP China Prospective (ICP) Study followed up these three populations in 2015-2016. Seated BP were measured at least twice following at least 5 minutes of rest, using a random zero sphygmomanometer for the INTERMAP (baseline) and an oscillometric device (Omron HEM-907) for the ICP (follow-up). When calculating BP changes, baseline values were converted using equations developed in a calibration study. Timed 24-hr urine samples were collected at baseline and follow-up using the same protocol. Urinary Na and creatinine (Cr) were measured by emission flame photometry method at baseline and ion-selective electrode method at follow-up. BP and dietary Na changes over time were compared using student t test.
Results: Systolic BP increased considerably in all three sites; largest increment in Guangxi (18.6, 95% CI: 16.0-21.1 mm Hg, P<0.001) and smallest in Beijing (9.1, 6.3-11.8 mm Hg, P<0.001) (Table 1). Level of urinary Na was almost double in north (Beijing and Shanxi) than south (Guangxi) at follow-up (P<0.001), similar as baseline. On average, participants consumed 10.8 (4.7) and 11.8 (4.7) grams of salt at Beijing and Shanxi and 6.3 (3.0) grams of salt at Guangxi at follow-up, though a trend of reduction in Na/Cr (-3.7, 95% CI: -4.7- -2.6, P<0.001) overall was documented.
Conclusions: Systolic BP levels increased considerably in this cohort between 1997 and 2015 in rural China. Na consumption might have a declining trend, but still at a very high level at northern China.