To assess the predictive value of symmetrical ambulatory arterial stiffness index (S-AASI) for early renal impairment in patients with essential hypertension.Design and method:
In total, 253 patients with essential hypertension and without overt proteinuria were enrolled from the Department of Cardiology, Kunming Medical University Affiliated Ganmei Hospital between March 2012 and February 2013. Ambulatory blood pressure monitoring (ABPM) was recorded to calculate S-AASI. Urine microalbumin (mAlb), and serum cystatin C (CysC) and creatinine (SCr) were measured. Creatinine clearance rate (Ccr) was estimated by Cockcroft-Gault (CG) equations. Estimated glomerular filtration rate (eGFR) were estimated from serum creatinine using the abbreviated Modification of Diet in Renal Disease equation(MDRD) and Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI), and was estimated from CysC using the modify MacIsaac formulation. The relationship between S-AASI and early renal impairment was analyzed by correlation analysis and multivariable stepwise regression analysis.Results:
With the increase of S-AASI, mAlb and CysC were significantly increased, while eGFRCysC, eGFRMDRD, eGFRCKD-EPI, and Ccr were significantly decreased. Partial correlation analysis showed that S-AASI was positively correlated with mAlb (r = 0.633) and CysC (r = 0.640), and was negatively associated with eGFRCysC (r = −0.704), eGFRMDRD (r = −0.366), eGFRCKD-EPI (r = −0.326), and Ccr (r = −0.356) after controlling for age and waist circumference (P < 0.05 for all). In multivariable stepwise regression analysis, S-AASI was independently associated with mAlb/Cr (β = 0.645), Cys C (β = 0.644), eGFRCysC (β = −0.707), eGFRMDRD (β = −0.356), eGFRCKD-EPI (β = −0.278), and Ccr (β = −0.267) (P < 0.05 for all). A 0.01 increase in S-AASI resulted in an increase of 0.80 mg/g for mAlb and 0.02 mg/L for Cys C, and a reduction of 1.58 ml/min for eGFRCysC.Conclusions:
Our results demonstrate that the increased S-AASI may be an independent risk factor for early renal impairment in patients with essential hypertension. Associations of S-AASI and CysC equation were superior to SCr equations.