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)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. 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.
American Journal of Kidney Diseases : the Official Journal of the National Kidney Foundation, 2014, Vol 64, Issue 5, p. 714-722