Physicians preach caution when interpreting and implementing SPRINT trial results

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 - Blood Pressure

Since the National Institutes of Health  announced preliminary results of the SPRINT (Systolic Blood Pressure Intervention Trial) study in September, the medical community and media have touted its findings. The researchers found that lowering the systolic blood pressure goal to less than 120 mm Hg in adults with increased risk of cardiovascular events had numerous benefits compared with the typical goal of 140 mm Hg.

Still, in an editorial published online in the  Annals of Internal Medicine on Feb. 22, physicians Eduardo Ortiz, MD, MPH, and Paul A. James, MD, warned that the targets should only be applied to a small group of patients. Their view differed significantly from a cross-sectional, population based study published on Feb. 1 in the  Journal of the American College of Cardiology that found 16.8 million U.S. adults may benefit from a goal of less than 120 mm Hg.

In the SPRINT trial, adults who had a target of less than 120 mm Hg  had a 25 percent relative risk reduction in the primary composite outcome of MI, stroke, heart failure or death from cardiovascular causes. However, Ortiz and James noted that a 25 percent relative reduction corresponds to a decrease in event rates from 6.8 percent to 5.2 percent over 3.2 years.

They also estimated that for every 1,000 adults, 16 will benefit, 22 will be seriously harmed and 962 will not benefit or experience harm if they are treated to a goal of less than 120 mm Hg compared with 140 mm Hg.

“With such low event rates, statistically significant differences may not necessarily correspond to differences that patients or their physicians consider clinically significant,” they wrote. “It would be helpful if such studies incorporated assessment of patient preferences into their design. This could be accomplished by asking all study participants about their willingness to continue the treatment regimens after they know the trial results. Such preferences would require an unbiased assessment and explanation of the results and estimates of prognosis with continued long-term treatment in both groups, including information that an average of 98.4 percent of persons receiving the medications will not benefit.”

Ortiz and James added that serious adverse drug events occurred in 4.7 percent of adults in the 120 mm Hg group compared with 2.5 percent of adults in the 140 mm Hg group. The SPRINT researchers noted that the adverse events were possibly or definitely related to the intervention and led to more visits to the emergency department.

“The prevailing emphasis on relative over absolute risk reduction while ignoring harms of treatment for [blood pressure] seems intent on labeling more patients with hypertension and pushing for more aggressive drug therapy, especially in older patients,” Ortiz and James wrote. “However, evidence suggests that patients expect greater treatment benefits than physicians to justify the use of daily antihypertensive medications when presented with similar data on benefits and harms, and specialists are more likely than primary care physicians to believe that more aggressive treatment is beneficial.”

Ortiz and James recommended an evidence-based approach to determine which patients may benefit from lowering the goal to 120 mm Hg. They wrote that the approach in treating a relatively healthy 55 year old adult with high cardiovascular risk who takes no or few medications may differ from treating a 79 year old with multiple comorbidities who is taking multiple antihypertensive drugs and other medications. They also wrote that studies have failed to show patients with low cardiovascular risk benefit from more aggressive blood pressure treatment.

“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.