Objective: This study aims to investigate the correlation between the trajectory of systolic blood pressure (SBP) and new renal damage in a nonhypertensive population.
Patients and methods: This prospective cohort study included a total of 14 382 nonhypertensive individuals, employees of Kailuan Group of Companies, who took part in five healthy examinations in 2006-2007, 2008-2009, 2010-2011, 2012-2013, and 2014-2015, and had complete data. These individuals were divided into four groups according to the different trajectories of SBP: low-low, low-stable, middle-high, and high-high groups. The correlation between the trajectory of SBP and new renal damage in a nonhypertensive population was analyzed using a multivariate Cox's proportional hazard regression model.
Results: (a) A total of 14 382 individuals had complete data and the average age of these individuals was 44.6±10.8 years. Among these, 10 888 (75.7%) individuals were men and 3494 (24.3%) individuals were women. (b) These individuals were divided into four groups according to different trajectories of blood pressure: low-low group, accounting for 13.15% (blood pressure was <106 mmHg); low-stable group, accounting for 53.91% (blood pressure was between 115 and 116 mmHg); middle-high group, accounting for 28.77% (blood pressure was between 125 and 131 mmHg); and high-high group, accounting for 4.6% (blood pressure was between 126 and 151 mmHg). (c) With the increase in the trajectory of SBP, the detection rate of renal damage increased gradually. From the low-low group to the high-high group, the detection rates of estimated glomerular filtration rate (eGFR) less than 60 ml/min/1.73 m were 2.3, 2.4, 3.6, and 4.3%, respectively; the positive rates of urinary protein were 1.7, 2.9, 3.8, and 5.5%, respectively; and the detection rates of eGFR less than 60 ml/min/1.73 m or positive urinary protein were 4, 5.2, 7.3, and 9.3%, respectively (P<0.05). (d) After adjustment for other confounding factors, multivariate Cox's proportional hazard regression analysis showed that compared with the low-low group, the risk of eGFR less than 60 ml/min/1.73 m increased by nearly 1.5 times in the high-high group and in the low-stable, middle-high, and high-high groups, the risks of positive urinary protein, eGFR less than 60 ml/min/1.73 m, or positive urinary protein increased by 1.48-2.34 and 1.20-1.70 times, respectively.
Conclusion: In a nonhypertensive population, the high trajectory of SBP is a risk factor for kidney damage.