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

Abstract

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. 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. 2,739 participants with type 2 diabetes and nephropathy with at least 1 year of blood pressure measurements available. 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. 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. Mean visit-to-visit variability in systolic blood pressure from 3 to 12 months postrandomization was 12.0±6.8(SD)mmHg. 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. Observational study with the potential for confounding. In diabetic individuals with nephropathy, systolic blood pressure visit-to-visit variability is associated independently with hard kidney disease outcomes.