Supplementary Material for: Blood Pressure Variability in Older Patients with Chronic Kidney Disease

Introduction: An increased blood pressure variability (BPV) is associated with a high risk of cardiovascular events in the general population. This concept was scarcely tested in patients with chronic kidney disease. We investigated the behavior of BPV parameters in a large cohort of older patients with CKD. Methods: This retrospective cohort study included patients ≥ 75 years old with eGFR ≤ 60 ml/min. Three systolic and diastolic consecutive blood pressure (BP) measurements were obtained automatically per visit (short-term - 3 consecutive measurements) and across visits (long-term - across visits). We calculated: 1) standard deviation (SD); 2) coefficient of variation (SD divided by the BP average) and 3) variability independent of the mean (VIM). For each BPV parameter, patients were divided into four quartiles. Results: We included 1,063 patients (17,363 measurements). For short-BPV: the higher systolic BPV (SD and VIM) was associated with older age, a lower proportion of males and a higher proportion of patients with pulse pressure (PP) > 40 mmHg. Higher diastolic BPV (SD and VIM) was associated with lower body mass index, lower eGFR and a higher proportion of PP > 40 mmHg (for SD). Bland-Altman plots revealed comparable results between short- and long-term BPV. Conclusion: A higher BPV was associated with reduced renal function in older patients with chronic kidney disease. Our study also suggests that short- and long-term BPV can be used with similar results. Further studies are needed to confirm the association between BPV and outcomes and understand the physiological mechanisms underlying this correlation.