Visit-To-Visit Blood Pressure Variability Is A Major Risk Factor For Renal Outcomes In Hypertensive Patients: Evidence From The 20-Year Follow-Up Of The AngloScandinavian Cardiac Outcomes Trial (ASCOT)

Introduction: Observational studies showed that visit-to-visit blood pressure variability (BPV) is a significant independent risk factor for cardiovascular morbidity and all-cause mortality. However, the relation between BPV with renal outcomes remains controversial. Methods: In the ASCOT-Legacy Study, 7,092 hypertensive patients, aged 40-79 years, who had at least three other cardiovascular risk factors have been followed for up to 20 years to report the long-term determinants of renal outcomes. All available BP visit records (n=100,933) were included after excluding the first six months observations. The mean of systolic blood pressure (SBP) as a measure of BP control and the standard deviation (SD) of all SBPs as an estimate of visit-to-visit BPV were calculated for the five years of the trial. Participants were then followed for up to 15 years after the end of the trial using the UK National Health Service (NHS) electronic health records. Total renal outcomes (renal failure, chronic kidney disease, dialysis and transplantation) were measured using Cox proportional hazards model. Results: About one-third (n=2,354) of participants experienced at least one of the renal outcomes during the follow-up. Our findings showed that an increase per one SD (10.39 mmHg) in mean SBP was associated with a hazard ratio (HR) of 1.23 (95%CI 1.17-1.29; p<0.001) and an increase per one SD (4.72 mmHg) in BPV was associated with an HR of 1.20 (95%CI 1.14-1.26; p<0.001) for total renal outcomes. Likewise, BPV was associated with a higher risk of renal failure (1.19 [95%CI 1.13-1.26]; p<0.001), chronic kidney disease (1.25 [95%CI 1.08-1.44]; p=0.002), and dialysis and transplantation (1.43 [95%CI 1.19-1.71]; p<0.001) after adjusting for mean BP, number of visits and other confounding variables. Conclusions: Both mean SBP and BPV are strong predictors of long-term renal outcomes, but BPV, independent of mean BP, confers a significant additional risk and should be considered for future preventive and therapeutic strategies.