More than six months after the National Institutes of Health announced preliminary results of the SPRINT (Systolic Blood Pressure Intervention Trial) study, the impact of the trial is still hotly debated in cardiology circles.
When the findings were released on Sept. 11, Gary H. Gibbons, MD, director of the National Heart, Lung, and Blood Institute, said the study "provides potentially lifesaving information that will be useful to health care providers as they consider the best treatment options for some of their patients, particularly those over the age of 50.”
Still, how many people will benefit from lowering their systolic blood pressure goal to less than 120 mm Hg remains to be seen. Recently, researchers have come to far different conclusions, suggesting the discussion will likely continue for years to come.
A cross-sectional, population-based study published in the Journal of the American College of Cardiology found 16.8 million U.S. adults met the SPRINT trial’s eligibility criteria and may benefit from a systolic blood pressure goal of less than 120 mm Hg. The researchers, who evaluated NHANES (National Health and Nutrition Examination Survey) data, also estimated that 25.5 million U.S. adults older than 50 who have a systolic blood pressure of greater than 120 mm Hg are at an increased cardiovascular risk.
Meanwhile, Alan H. Gradman, MD, of Temple University in Philadelphia, wrote an editorial in the same issue of the Journal of the American College of Cardiology and mentioned that it was important to consider SPRINT’s inclusion criteria before making any wholesale changes in blood pressure guidelines. For instance, he noted the study excluded patients with diabetes, cerebrovascular disease and drug-resistant hypertension and included a large number of patients with mild chronic kidney disease and elderly people with well-controlled hypertension. In addition, only 16.7 percent of patients had cardiovascular disease.
“The differing results of SPRINT and ACCORD, 2 studies of similar design conducted by the same research group evaluating the same [blood pressure] targets, are likely due to the composition of the 2 patient populations,” Gradman wrote. “Although the SPRINT results are likely valid for the study as a whole, its therapeutic implications cannot be automatically applied to every patient who met the inclusion criteria. A patient may belong to a subgroup (e.g., patients with [coronary artery disease]) that made a very small statistical contribution to the overall results. It is possible that a study conducted exclusively in that subgroup would yield very different results.”
Physicians Eduardo Ortiz, MD, MPH, and Paul A. James, MD, in an editorial published in the Annals of Internal Medicine, also warned that the targets should only be applied to a small group of patients. They estimated that for every 1,000 adults, only 16 would benefit from having a target systolic blood pressure of less than 120 mm Hg instead of the standard of less than 140 mm Hg.
They also noted that serious adverse drug events were nearly twice as common in adults in the 120 mm Hg group and were more likely to be related to the intervention and lead to more emergency department visits.
“We do not believe that the small absolute benefit seen in SPRINT provides convincing evidence that large segments of the population should be treated with additional drugs to a systolic [blood pressure] goal less than 120 mm Hg, especially when the adverse events, costs, and burden of such treatment are considered,” they wrote.