Visit-to-visit systolic blood pressure variability predicts treatment-related adverse event of hyponatremia in SPRINT.

Hypertension is a common condition and an important cardiovascular risk factor. SPRINT trial showed that the beneficial effects of targeting systolic blood pressure <120 mm Hg were accompanied by more adverse events. De-identified SPRINT database was used for this analysis. All subjects in each group that achieved their respective target blood pressure (<120, intensive; <140, standard) were included. Only readings after reaching target blood pressure for the first time were included. Subjects that never reached target or had <2 readings upon reaching target were excluded. Coefficient of Variation (CV) of systolic blood pressure was calculated for each subject to characterize variability. Cox proportional hazards regression was used in the overall cohort as well as the intensive and standard treatment subgroups separately, to identify the effect of CV of systolic blood pressure on occurrence of hyponatremia. P<.05 was considered statistically significant. A total of 8884 subjects met the inclusion criteria; 4323 in intensive and 4561 in standard group. Two hundred and sixty five hyponatremic events occurred in the overall cohort; 168 in intensive, and 127 in standard treatment group. CV of systolic blood pressure consistently and independently predicted a greater hazard of hyponatremia on overall (HR 1.08, P<.001), as well as separate regressions by treatment arms (each HR=1.08 and P<.05). In conclusion, visit-to-visit systolic blood pressure variability is independently associated with a small but significant risk of hyponatremia in the SPRINT trial.