Pulse pressure and progression of chronic kidney disease.

OBJECTIVES: Pulse pressure (PP) is a predictor of adverse outcomes in patients on haemodialysis and with predialysis chronic kidney disease (CKD). However, the relationship between PP and kidney disease progression is not clear in mild to moderate CKD, which this study aimed to investigate.

METHODS: CKD patients (n=329) were followed up for 172 +/- 93 days (mean +/- SD). The clinical characteristics at baseline were, age 64 +/- 17 years, 62% males, 27% diabetics, estimated glomerular filtration rate (eGFR) 39 +/- 18 ml/min per 1.73 m2, systolic blood pressure (SBP) 141 +/- 24 mm Hg, diastolic blood pressure (DBP) 76 +/- 12 mm Hg and PP 65 +/- 20 mm Hg. On follow-up, eGFR decreased (39 +/- 18 vs. 38+/-18 ml/min per 1.73 m2; p<0.01), SBP and PP improved (141 +/- 24 mm Hg vs. 133 +/- 19 mm Hg; p<0.001; and 65 +/- 20 mm Hg vs. 59+/-17 mm Hg; p<0.001), and DBP was unchanged.

RESULTS: Declining kidney function as assessed by eGFR was inversely related to baseline SBP (r=-0.15; p<0.01) and PP (r=-0.18; p<0.001), but no relationship with DBP was observed. During follow-up, baseline PP correlated with declining eGFR (r=-0.15; p<0.01) similar to SBP (r=-0.15; p<0.01), but DBP did not. Patients with declining eGFR had higher PP (69 +/- 20 mm Hg vs. 62 +/- 20 mm Hg; p<0.005), higher SBP (145 +/- 23 mm Hg vs. 138 +/- 25 mm Hg; p<0.05) but similar DBP (76 +/- 12 mm Hg vs. 76 +/- 12 mm Hg; p=0.8) compared with patients with stable eGFR.

CONCLUSIONS: Baseline PP was the only predictor of eGFR decline adjusted for age, baseline eGFR, diabetes, haemoglobin and use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. PP >65 mm Hg was associated declining renal function (log rank chi-square; p<0.05). This study suggests that PP is a better predictor of adverse renal outcome even in mild to moderate CKD, than DBP or even SBP.