Effect of Intense vs. Standard Hypertension Management on Nighttime Blood Pressure - an Ancillary Study to SPRINT

Hypertension is a major risk factor for cardiovascular and renal disease, and a leading cause
of premature mortality worldwide. Early hypertension studies showed that treating elevated
blood pressure (BP) reduces patients' risk of cardiovascular disease and all-cause mortality.
In subsequent research, patients achieved greater improvement in cardiovascular outcomes when
their treatment was aimed at a moderate systolic BP target (<150mmHg) than at higher targets.
Although observational data suggest that even lower BP targets may be beneficial, this has
not been seen in randomized trials; instead, "intense" treatment of hypertension (i.e., to a
target systolic BP <120mmHg) was found to have no effect on participants' risk for renal
disease, cardiovascular disease, or all-cause mortality.

One potential explanation for this apparent lack of benefit of intense BP targets is that the
study protocols targeted reductions in clinic BP rather than ambulatory BP. Ambulatory BP
monitoring (ABPM) allows for assessment of BP throughout the day and night. Of all the BP
measurements, nighttime systolic BP appears to be the best predictor of cardiovascular
disease and all-cause mortality. Because recent trials assessing intense BP targets did not
include ambulatory BP measurements, the effect of intensive treatment on nighttime BP is
largely unknown.

To address this important gap in knowledge, we will conduct ABPM in 600 participants as part
of an ancillary study to the ongoing Systolic Blood Pressure Intervention Trial (SPRINT). The
goal of the ancillary study is to evaluate the effect of intensive vs. standard clinic based
BP targets on nighttime BP (primary outcome), as well as night/day BP ratio, timing of peak
BP, 24hr BP, and BP variability (secondary outcomes). The SPRINT trial includes approximately
9250 participants at high risk for cardiovascular disease.

The investigators hypothesize that intense targeting of clinic systolic BP does not lower
nighttime systolic BP compared to a standard target.