Visit-to-Visit Variability in Blood Pressure and Kidney and Cardiovascular Outcomes in Patients With Type 2 Diabetes and Nephropathy: A Post Hoc Analysis From the RENAAL Study and the Irbesartan Diabetic Nephropathy Trial

Background: Increased systolic blood pressure variability between outpatient visits is associated with increased incidence of cardiovascular end points. However, few studies have examined the association of visit-to-visit variability in systolic blood pressure with clinically relevant kidney disease outcomes. We analyzed the association of systolic blood pressure visit-to-visit variability with renal and cardiovascular morbidity and mortality among individuals with diabetes and nephropathy. Study Design: Observational analysis of IDNT (Irbesartan Diabetic Nephropathy Trial) and the RENAAL (Reduction of End Points in Non-Insulin-Dependent Diabetes With the Angiotensin II Antagonist Losartan) Study. Setting & Participants: 2,739 participants with type 2 diabetes and nephropathy with at least 1 year of blood pressure measurements available. Predictors: Systolic blood pressure visit-to-visit variability was calculated from the SD of the systolic blood pressure from 4 visits occurring 3-12 months postrandomization. Outcomes: The kidney disease outcome was defined as time to confirmed doubling of serum creatinine level, end-stage renal disease, or death; the cardiovascular outcome was defined as time to cardiovascular death, myocardial infarction, stroke, hospitalization for heart failure, or revascularization. Results: Mean visit-to-visit variability in systolic blood pressure from 3 to 12 months postrandomization was 12.0 +/- 6.8 (SD) mm Hg. Following this ascertainment period, there were 954 kidney disease and 542 cardiovascular events. Greater systolic blood pressure visit-to-visit variability was associated independently with increased risk of the composite kidney disease end point (HR per 1-SD increment, 1.08 [95% CI, 1.01-1.16]; P = 0.02) and end-stage renal disease, but not with the cardiovascular outcome. Limitations: Observational study with the potential for confounding. Conclusions: In diabetic individuals with nephropathy, systolic blood pressure visit-to-visit variability is associated independently with hard kidney disease outcomes. (C) 2014 by the National Kidney Foundation, Inc.