Effect of Inflammation on the Relationship of Pulse Pressure and Mortality in Haemodialysis

BACKGROUND/AIM: The effect of hypertension on mortality in haemodialysis patients is controversial and can be confounded by non-traditional risk factors like systemic inflammation. This study examined the effect of systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP) on mortality in haemodialysis patients, separately with and without markers of systemic inflammation. METHODS: Data from the United States Renal Data System were analysed for 9,862 patients receiving haemodialysis on December 31, 1993, followed through May 2005. RESULTS: In Cox regression analysis, increased age, diabetes, low albumin, high white blood count, low cholesterol, low haemoglobin, high phosphate, low DBP, and cardiovascular comorbidity were associated with high mortality, but SBP was not. Elevated PP adjusted for SBP, age, diabetes, haemoglobin, albumin, cholesterol, calcium, phosphate, parathyroid hormone, and white blood count was associated with higher mortality [adjusted hazard ratio, PP 1.006 (95% confidence interval, CI, 1.002-1.010); SBP 0.993 (95% CI 0.990-0.996)]. In dual models, PP adjusted for SBP then DBP was associated with higher mortality [PP 1.029 (95% CI 1.027-1.032); SBP 0.981 (95% CI 0.979-0.983); PP 1.010 (95% CI 1.008-1.011); DBP 0.981 (95% CI 0.979-0.983)]. Increasing PP deciles >70 mm Hg were associated with increasing mortality in the absence of markers of systemic inflammation (white blood count >10 × 10(9)/l, albumin <3.5 g/dl, diabetes), but not in their presence. CONCLUSION: PP was a better indicator of adverse outcome than DBP or SBP. Inflammation-associated injury may mask the effect of PP on mortality in haemodialysis patients.