There is particular concern about harms of tight control in elderly persons, although a SPRINT substudy involving patients 75 years of age or older showed significant benefit with the systolic blood-pressure target of less than 120 mm Hg, with absolute rates of and relative risks of hypotension, syncope, and electrolyte abnormalities that were similar to those in the overall SPRINT population; this substudy extended the benefits seen in an earlier trial involving elderly persons with a systolic blood-pressure target of less than 150 mm Hg.