Understanding stroke: 25-year study uncovers disparities & insights

0:00:54.0 Host: Hello and welcome to Population Healthy, a podcast from the University of Michigan School of Public Health. Join us as we dig into important health topics, stuff that affects the health of all of us at a population level, from the microscopic to the macroeconomic, the social to the environmental, from cities to neighborhoods, states, to countries and around the world.

0:01:17.7 Host: Every 40 seconds someone in the US has a stroke, which is a leading cause of long-term disability and death, especially among older adults. Today we're joined by two University of Michigan researchers who've been studying stroke for decades.

0:01:27.7 Lewis Morgenstern: I'm Lewis Morgenstern. I'm a professor of neurology and epidemiology at the University of Michigan Medical School and School of Public Health. 

0:01:37.3 Lynda Lisabeth: I'm Lynda Lisabeth. I'm a professor of epidemiology and research professor of neurology at the University of Michigan School of Public Health.

0:01:44.7 Host: Before we delve into their research, we ask Morgenstern and Lisabeth to tell us more about stroke and which populations are at highest risk.

0:01:51.4 LM: Stroke is a brain disease. It occurs when a blood vessel is blocked and blood does not get to a certain part of the brain and that part of the brain dies. The common symptoms of stroke are weakness or numbness on one side of the body, difficulty speaking or understanding, sudden unexplained clumsiness or falling. Another symptom is having a shade come down over your eye, so you're unable to see the brain is organized so that the right side of the brain controls the left side of the body, and the left side of the brain controls the right side of the body. So when people have a stroke, it usually affects one side of the brain and the other side of the body.

0:02:32.4 LL: Some of the main risk factors include hypertension or having high blood pressure. That's the largest stroke risk factor. Other risk factors include diabetes, atrial fibrillation, which is an irregular heartbeat. Having high cholesterol. Stroke is a disease that escalates with age. It also impacts certain minority groups more often and particularly at younger ages. This includes black Americans, Hispanic Americans, and the subgroup that we study. Mexican American persons. It also impacts women. Uniquely. Women have an elevated risk of stroke at elderly ages, partly because they live longer, but they also have worse stroke outcomes compared to men.

0:03:18.2 Host: Morgenstern and Lisabeth have been running a stroke research study called BASIC for nearly 25 years. The study focuses on health equity and stroke health disparities faced by Mexican Americans in Corpus Christi, Texas.

0:03:46.9 LM: The brain attack surveillance in Corpus Christi project or BASIC, was started in the 1990s. It was an offshoot of a project that was ongoing called the Corpus Christi Hart Project. This was run by a group of investigators outta the University of Texas Houston School of Public Health. And when I was down there, I started working with them. The whole basis of BASIC is health equity, trying to understand why Mexican Americans have a greater burden of vascular disease, both heart disease and stroke. And so we started a project where we counted every single stroke in Nueces County, Texas. The largest city in Nueces County is Corpus Christi, and we started that project in January 1st, 2000, and we've done it every day since. We wanted to know whether stroke was more common in Mexican Americans than non-Hispanic whites. We were interested in risk factor differences. We were interested to see whether Mexican Americans had stroke at younger ages than non-Hispanic whites. We were interested to see whether recurrence of stroke happen more in Mexican Americans and whether death following stroke was more common in Mexican Americans.

0:04:43.6 LL: Some of our early findings suggested, for example, that Mexican American persons were more likely to survive their stroke compared with non-Hispanic white persons. So one of the evolutions that we then turned to was trying to understand what that survival looked like, what were stroke outcomes in Mexican American persons. So started to follow stroke patients after they left the hospital, returned home. And measuring a number of different outcomes that we focus on in stroke, things like function and cognition and quality of life as examples. We also, were interested in understanding trends over time because we have collected data for such a long period of time. We look at how stroke risk has evolved over time, how stroke outcomes have evolved over time and know where differences occur. So that can tell us are we making progress towards reducing disparities, are new disparities emerging. We have also started to look at things like post-acute care and what kind of rehabilitation or informal caregiving are stroke patients receiving when they go home.

0:05:54.3 LM: We call BASIC, primarily a surveillance project, which means that we want to capture every single person who has a stroke in Nueces County, Texas since January 1st, 2000 up to the present and going forward, which means that we employ a set of University of Michigan staff who regularly interact with the medical teams at hospitals by screening the logs of patients who come through the emergency department or directly admitted, they go to the intensive care units and the floors and they find patients who have had a stroke. They then copy their records, removing all identifying information and electronically send it up to us so that the stroke neurologist can look at the case and determine whether it in fact was a stroke or not. That's a process that we call validation. Once we have validated the stroke, the staff then contacts the patient and caregivers and we interview the patient and obtain information about their risk factors, their living situations, other associated, information, socioeconomic status, et cetera.

0:07:13.2 LM: And we collect all that information in an encrypted password protected database. And then we use that information after statistical analysis to write our manuscripts. After somebody is identified, we go through an informed consent process to make sure that they want to participate. We explain the study, they agree and and sign the informed consent. We interview them. We also have a really important project that is at the heart of BASIC where we investigate the association of sleep apnea with stroke. And so we offer participants the opportunity to have a sleep study and to see whether they have obstructive sleep apnea and look at that as a risk factor for stroke among these two populations, Mexican Americans and non-Hispanic whites. And then we follow participants out for 90 days to see their outcome. And at 90 days we visit with them Again, we do a standardized neurologic assessment. We do several surveys and scales to determine how they're doing functionally, how they're doing cognitively and how they're doing neurologically. And we also look at other outcome measures that are very specific to patients. We look at depression, we look at other aspects of patient reported outcomes that reflect, you know, how people are thriving in life.

0:08:41.8 Host: Tell us a little bit more about your research on the connection between stroke and sleep apnea.

0:08:44.2 LL: We've Seen an explosion of research in recent years related to sleep disorder breathing. So one of the aspects that we've been able to bring is an understanding of the intersection of stroke and sleep disorder breathing, how that impacts stroke outcomes with the idea that if there is an association, sleep disorder breathing is something that could be treated and then potentially improve stroke outcomes. The other aspect that we focus on is health equity, and we've been able to show that Mexican Americans with stroke have a higher prevalence in more severe sleep, disordered breathing than non-Hispanic whites with stroke. And therefore, again, if we can treat sleep disorder breathing, it might also be a way for us to improve the disparities that we see in stroke outcomes. We have shown associations, between sleep disordered breathing and stroke outcomes. And we've also shown that in some cases they're stronger among the Mexican Americans with stroke.

0:09:42.1 Host: What Are some other interesting findings that you've uncovered?

0:09:49.5 LL: Early on, we were able to demonstrate that Mexican American persons have a higher risk of stroke, especially at younger ages. We've also demonstrated that Mexican Americans earlier in the study had a higher risk of stroke recurrence or going on to have a second stroke, but better mortality following stroke. We have demonstrated that Mexican Americans have worse stroke outcomes at 90 days following stroke, which is a common timeframe for assessing stroke outcomes compared with their non-Hispanic white counterparts. And this is really across the board, functional outcome, cognitive outcome, depressive symptoms, quality of life. And we're still trying to understand why that is, which has led to some of the evolution in terms of looking at post-acute care. We're also looking into whether or not some of these patient reported outcome measures are different. And so those differences in function and cognition that we saw early on have led us now to be thinking about what about things like returning to work and returning to driving and things that we know are really important to patients and families over time, we have seen some very favorable trends with stroke incidents going down over time, which is a positive finding from a public health perspective.

0:11:02.1 LL: And that's happening in both ethnic groups. We have recently seen some increases in stroke rates in the younger non-Hispanic white population that we study. And when I say younger, I mean 45 to 59, some increases and we don't really know why that is, but again, leads us to thinking about how we can tackle that in some of our next steps. Another thing that has sort of evolved, we've always been a health equity study and have made a lot of these ethnic comparisons over time to try to understand how stroke burden has changed. One of our more recent directions is now to do a deeper dive within the Mexican American stroke population to try to understand what explains variability and outcomes within that subgroup of the population. Because there is variability and there may be both positive factors, things that lead to better outcomes, or there could be factors that are detrimental or risk factors. And so we're doing a much deeper dive now to try to understand that.

0:12:04.7 Host: The earliest findings of the study were that there were these huge disparities between the populations and those disparities have shrunk dramatically. But there's interesting findings, as Linda mentioned, you know, the younger non-Hispanic whites seem to be doing not as well. And so there's always more questions, but it just shows that longitudinal studies like the one we have constantly bring up new information.

0:12:31.8 LL: There's a lot of administrative data that's available, for example, through Medicare or through the state of Texas, which really measure healthcare utilization. So what we're doing now to further expand the utility of BASIC is to link BASIC, which has this rich and very detailed population based data to these administrative data sources. And we're going to do that even more with this recent award by linking to Medicaid and by linking to Medicare Part D, which is drug utilization. And we really feel like we're gonna be able to answer some interesting questions about patterns of healthcare utilization before and after a stroke, how those might differ by different subgroups in our population, which might again speak to possible intervention points or other aspects of care and healthcare utilization in the community. You're.

0:13:22.2 LM: Managing all of this research in Corpus Christi, Texas from all the way here in Ann Arbor, Michigan. How does that Work?

0:13:29.7 LM: Running a project that is 1400 miles away from Ann Arbor involves a lot of collaboration and a lot of work by a lot of different people. We routinely maintain our strong collaborations with the two hospital systems in Nueces County, Texas. We have a number of physicians who we collaborate with and give us ideas about what's going on in the local community with respect to the medical care and stroke. Specifically, we work with several different hospital administrators in both hospital systems as well. And the nurses, in the hospitals are critical parts of what we do. They help us identify participants. They explain to the patients who we are.

0:14:10.0 LM: We've been in the community long enough that many of the patients and their families have already heard about us, which is an advantage. We have this, cadre of University of Michigan employees, anywhere between 10 and 25, depending upon how our grant funding is going, who walk around hospitals with their white coat on and their big maze m on the pocket and regularly talk to patients and families and involve them in the work. Then here in Ann Arbor, in addition to the faculty investigators, we have a variety of students, graduate students, master's students, PhD students from the School of Public Health in several different departments, as well as in the medical school, medical students, residents, fellows as well who have been involved. And then we have external collaborators around the country and around the world who have done research with us and used BASIC data to write papers.

0:15:03.5 Host: Morgenstern and Lisabeth were recently recognized with a prestigious Javits and Neuroscience investigator Award from the National Institute of Neurological Disorders and Stroke for their longstanding and impactful work. And that's not the only indicator of the impact of this important research.

0:15:25.6 LM: We've written like 150 papers. We've given hundreds of presentations at meetings, and I think BASIC is really known throughout the world when we submit papers. Now, most of the reviews say something like, you know, this is from the well-known BASIC project. We recently presented findings at the European Stroke Conference. Both of us have received lots of communications from people all over the world asking about our work and knowledgeable about our work. So yeah, I think that BASIC has really illuminated a lot of very interesting aspects, not only of health equity, which is its primary mission, but observations about the clinical care of stroke patients in a community setting. Most of the data about the medical care of stroke comes from big ivory tower hospitals like the one across the street, but BASIC is in a community that doesn't have a medical school. It's what we call kind of a real world setting. And so our observations about care in this community where there is very good medical care are really important.

0:16:20.6 LM: BASIC success is really due to a number of factors. Number one, there are a lot of really diverse people involved in the project, starting with Linda and myself, right? So Linda is a PhD epidemiologist, I'm a physician. And I think that our collaboration has really been fantastic in the ability to approach this project from two very different beginnings of our training and our evolution as professionals and then all the other collaborators that have brought so much to the study. You know, the fantastic questions that our doctoral students ask, the really interesting points of view that our stroke fellows have.

0:17:05.0 LM: I mean, so many different people from both the school of Public Health and the medical school have really contributed to this study. And then it's the community who have really opened their arms to us and just been so fantastic and so proud of this study. The patients, the families, the health systems. I love to go down to Corpus Christi. I just feel so at home there. I feel the warmth of the population and the fact that they're proud of this study. Linda and I, as scientists have always been very transparent and open about the findings and, you know, making sure that we publish all information no matter, you know, whether it looks good or bad for the study or for what's going on. So I think that all those factors have been really important.

0:17:48.9 LM: Stroke is the most preventable of all bad diseases, and you can tell that because the rates of stroke have declined dramatically in high income countries. Like the United States. Stroke used to be the third leading cause of death in the US. It's now sixth. And so these numbers have really emphasized that. We know a lot about how to prevent it, but these things need to be done by individuals. They're not done by health providers. So we know that it's really, really important for people to have their blood pressure checked. High blood pressure number one, cause a stroke throughout the world. If you have high blood pressure, reducing salt in your diet, getting plenty of exercise, getting medicines from your primary care doctor to try to keep that blood pressure 120 over 80, 120/80 or less. Exercise is very important. Not smoking, no tobacco products, staying away from secondhand smoke, important diet, really critical high-end protein, but lean protein.

0:19:07.3 LM: So fish and white meat, chicken, using olive oil, kind of a Mediterranean diet, staying away from saturated fats as you see in red meat and egg yolks and those types of things. So these are all things that you can talk to your primary care doctor about and try to get assessed, and it really makes a big difference. It's really, really important that if you observe anybody having any of the symptoms of stroke, that you immediately call 911 because the therapies that we have for somebody who is having a stroke are tremendously effective. We have drugs that break open the blood clot. We have the use of a catheter to go into the artery where the blood clot is and remove that clot. But the earlier we can do that, the better. Right? Nerve cells die in a time dependent fraction. So you really want to get to the hospital immediately. And calling 911 is important because not only will you get there fast, but in most hospitals, the ambulance driver calls ahead mobilizes the stroke team, so we're all prepped and ready to take care of the patient. So really, really important to call 911 for any of those stroke symptoms.

0:20:10.6 Host: Thanks for listening to this episode of Population Healthy from the University of Michigan School of Public Health. Visit our website, population-healthy.com for more resources on the topics discussed in this episode, and to find more episodes. If you enjoyed the show, remember to subscribe, rate and review wherever you listen to podcasts. Be sure to follow us on social media and consider sharing this episode with friends. Population Healthy is produced by Andrea LaFerle, Brian Lillie, and Crissy Zamarron and hosted by Michael Kasiborski. Hope you can join us for our next episode where we'll dig in further to public health topics that affect all of us at a population level.