Doctors' belief in big numbers leads to study that could help prevent second stroke

The scale of his recent stroke prevention study with fellow neurologist Bruce Ovbiagele and biostatistician Kinfe Bishu at the Medical University of South Carolina was huge. They looked at more than a decade’s worth of data from National Health and Nutrition Examination Surveys. 

What they found suggests many lives might be saved if stroke survivors and their doctors follow new guidelines from the American College of Cardiology/American Heart Association that lower the threshold for high blood pressure.

“Hypertension, or high blood pressure, is arguably the strongest risk factor for a stroke,” Lekoubou said. “We also know that stroke survivors are at a higher risk of having a second stroke, and they die at a higher rate than people having a first stroke.” 

Last year, the ACC/AHA lowered the threshold for high blood pressure from 140 systolic and 90 diastolic, 140/90, to 130/80. “That’s a big difference,” Lekoubou said.

When he and his colleagues at MUSC saw the new guideline, they considered it long overdue. “We just jumped on it and said let’s look at how this will impact our stroke survivors.”

They set out to predict what might happen if stroke survivors followed the new guidelines, mining the National Health and Nutrition Examination Surveys. They compared the death rates of stroke survivors who kept their blood pressure under 140/90 to people who hit the lower mark of 130/80. Fewer people in the lower level group died during the study period. 

“One key message from this project is that we want to really raise awareness of the fact that we as physicians and medical providers should move from that inertia lane and be more proactive. Discuss with patients the need to go further down in their blood pressure target.”

He said there has been some reluctance to strive for the lower number, but it’s time for that to change. “One-40 over 90 for a stroke survivor is not enough. Let’s go as low as we can safely go.”

Lifestyle changes such as more exercise, weight loss and salt reduction can help lower blood pressure. There are also medications. “Stroke patients may have side effects if their blood pressure goes too low,” Lekoubou cautions. “But they’re not as common as people think they are.”

He also points out limitations to his team’s study. “It’s a top-down approach. We went back and looked at what people collected and analyzed that. One limitation is the way stroke was defined in this study — it was self-report.” That means there was no medical confirmation that the person had suffered a stroke. "The second limitation is that when the survey was done, they didn’t do three separate visits as recommended. They did three blood pressure checks at one visit.”

He hopes the research out of MUSC leads to larger studies. “We are privileged to have a very strong stroke program at MUSC. MUSC is sort of the rising star in terms of stroke in the nation.”