Introduction: Hypertension is one of the principal modifiable risk factors in the management of chronic kidney disease. Clinic blood pressure (BP) readings have traditionally been used for assessment. We set out to determine if non-traditional haemodynamic parameters such as aortic stiffness and central blood pressure (CBP) have an increased predictive power of all-cause mortality compared to clinic BP readings and 24 hour ambulatory blood pressure (ABPM) measurements.
Methods: Two-hundred patients (mean age 68.8 + 11.5 years) with stages 3 to 4 CKD were recruited in a prospective study of haemodynamic parameters and outcome. Baseline measurements were clinic BP, 24 hour ABPM (Diasys® Novocor, UK), CBP (Sphygmacor® AtCor, Australia) and aortic stiffness, measured by carotid-femoral pulse wave velocity (Complior® Artech, France). However not all patients had a complete set of all measurements. A nocturnal drop in systolic BP of <10% on 24 hour ABPM identified ‘non-dipper’ patients. Patients were followed up until the end points of death or dialysis.
Results: Forty-six patients died during follow up (median follow up 67.8 months, 95% CI 62.8-72.7) and 35 required dialysis. Sixteen of the later subsequently died. Aortic stiffness, CBP and the mean systolic ABPM BP and ‘non-dipping’ were shown to be significant predictors of all-cause mortality in univariate analysis (P <0.001, P <0.03, P < 0.05, P <0.05 respectively) . In Cox regression analysis adjusted for traditional vascular risk factors and severity of renal failure; aortic stiffness, mean systolic 24 hour ABPM BP and ‘non-dipping’ remained significant predictors of mortality. Cox-model derived relative risk [95%CI] 1.41 [1.01-1.98], 1.03 [1.01- 1.05] and 2.62 [1.20-5.75) respectively.
Conclusions: In this study of elderly patients with CKD stages 3 to 4 we showed that increased aortic stiffness, average systolic readings on 24 hour ABPM and ‘non-dipping’ on 24 hour ABPM were potentially significant predictors of all-cause mortality.