Visit-to-visit Systolic Blood Pressure Variability and Clinical Implications in a High-Risk Hypertensive Population: an Analysis of the SPRINT Data

Aim. The prognostic significance of blood pressure variability (BPV) for the occurrence of cardiovascular (CV) events and mortality is still debated. Differences in its methodological assessment and in patients’ characteristics have been both indicated as potential explanations to the discrepant findings. We used the Systolic Blood Pressure Intervention Trial (SPRINT) dataset to explore this unresolved issue. Methods. We applied three protocols that differed by timing and number of study visits to calculate the same index (coefficient of variation, CoV, %) of long-term (visit-to-visit) systolic BPV: 1) quarterly until outcome occurrence, including monthly assessment during the 3-months titration period; 2) quarterly until outcome occurrence, excluding titration period; and 3) quarterly for 1 year, excluding titration period. Outcomes of interest were primary events and all-cause mortality. Crude and progressively adjusted Cox proportional hazard models were used to assess the risk of outcomes according to the three estimates of visit-to-visit systolic BPV. Results. An optimal visit-to-visit systolic BPV associated with lower incidence of the primary outcome (CoV 5-10%) and all-cause mortality (CoV ≤8%), or any of the two (CoV 5-11%), was identified according to the first two estimates only. This effect was independent of mean systolic BP. Optimal visit-to-visit systolic BPV appeared to confer additional protection to intensive BP lowering. Conversely, different BPV apparently worsened CV risk among standard-treated patients. Clinical correlates of suboptimal BPV included older age, female gender, non-White ethnicity, smoke, and pre-existing CV and renal disease. Conclusions. Visit-to-visit systolic BPV might add prognostic value to the estimation of CV risk in high-risk, non-diabetic hypertensive patients, but the protocol adopted for its calculation is crucial. An effort to standardize BPV assessment is worthwhile.