Kari Gillmeyer, MD, MSC - phaware® interview 537

Sep 10, 2025

Delays in diagnosing and treating pulmonary hypertension (PH) can have life-altering consequences. In this episode, Dr. Kari Gillmeyer, discusses her groundbreaking study on PH care networks. She explores why so many patients experience delays, how geography and provider access play a role, and what can be done to improve timeliness of care.

This Special Edition Episode Sponsored by: Johnson & Johnson

My name is Kari Gillmeyer. I am a pulmonary and critical care physician and a clinical and health services researcher at Boston University and VA Boston. I've been doing pulmonary hypertension research pretty much since the start of my research career, probably six or seven years ago.

I am excited to be here today to tell you about a study that we did on exploring care networks for pulmonary hypertension and some of the implications that our findings may have on improving timeliness of pulmonary hypertension care.

Our motivation for this study really came from an awareness and an appreciation of the substantial documented gaps in both the timeliness and the quality of pulmonary hypertension care. For example, we know that the time from symptom onset to diagnosis for folks with pulmonary hypertension, specifically pulmonary arterial hypertension, is two to four years. For those with chronic thromboembolic pulmonary hypertension, it's more than a year. Unfortunately, over the last two decades or so, those delays in making a diagnosis for pulmonary hypertension have not improved, despite the efforts, including the efforts of people like phaware® and this podcast to improve the awareness of the disease. We know that these delays in making the diagnosis for pulmonary hypertension have significant long-term impacts and outcomes for patients.

The delay to diagnosis is certainly not improving, and we would expect to see improvements over time given all the efforts to improve the awareness of the disease, all the efforts in the research realm to try to improve our understanding of the disease, and yet it's not improving. I think that we can kind of hypothesize what some of these reasons are for the delay. I think we know some of them and we can hypothesize other reasons.

For example, we know that patients often present with very nonspecific symptoms, especially earlier in their disease. They may come in feeling a little short of breath. They may have some lightheadedness. These types of symptoms can be seen in a whole host of other diseases. I think that's one reason why this disease gets missed. Then, I think some of the other reasons include just a lack of awareness and a lack of comfort with managing this disease, particularly among general practitioners and primary care providers. But I would say even among some specialists, cardiologists, and pulmonologists who don't see folks with pulmonary hypertension that often.

A lot of those factors, a lot of those, what we call social determinants of health broadly, certainly have an impact on delays in care. Not this specific study, but in parallel to this work, we're looking at trying to identify what those specific factors are. For example, we know that patients who are on Medicaid experience greater delays in getting into care. That's been shown in other disease processes as well. These folks have fewer options for who they can receive care from. They have greater barriers to overcome from an insurance perspective. That's just one example, but certainly a lot of these issues are at play here.

Recognizing these significant delays in care and recognizing that we don't really have a full grasp on why these are happening, we sought to conduct a population level study to try to evaluate care networks for pulmonary hypertension, to try to understand where patients are receiving their pulmonary hypertension care, from whom they're receiving their pulmonary hypertension care, meaning what type of specialists are providing the care, and then to look at kind of referrals for patterns of care as sort of a first step to understanding where some of these gaps in getting patients into expert care might lie.

We used a database called the all-payer claims database, which as the name implies, includes claims data for all payers, meaning commercial payers, Medicaid, Medicare. This is a really strong and powerful type of database where we can kind of look at the entire population and see where patients across the entire population are receiving their care. Importantly, this data set also includes something called the National Provider Identification Number from the provider standpoint, so we can connect this claims database with provider data so that we can understand very specifically what types of providers are caring for patients with pulmonary hypertension.

Then, using that database, we used a tool called Social Network Analysis, which for those who have not heard of this term before, is basically a way to look at relationships within a network. A network can be made up of any type of people. In this case, we're interested in looking at providers in the network. Then, the relationships between those providers are patients that they share. For example, if provider A saw a patient with pulmonary hypertension and provider B also saw that same patient with pulmonary hypertension, those two providers would be connected in the network.

By seeing what providers are sharing patients, it allows us to kind of understand where these referral patterns might be happening, and importantly, where there might be gaps, where people who are seeing, for example, a primary care doctor who aren't getting in to see a specialist or who aren't getting in to see a PH expert, where those gaps might be happening across the population level.

We found about 9,000 patients in our database that have pulmonary hypertension, and we found about 5,000 providers who take care of those patients. We created these networks from these patients and providers. Some of the main things that we found were that in the state of Massachusetts, which is where this database came from, we found only 35 pulmonary hypertension experts. That represents one pulmonary hypertension expert to every 250 patients with pulmonary hypertension.

This data set only captured about four years of data. so we think that that number is significantly higher, meaning that there are far more patients with pulmonary hypertension that we identified. So, we think that ratio is even higher. Obviously, pulmonary hypertension experts are a limited resource. There are far too few of them to be providing care for patients with pulmonary hypertension. That's one of the main findings that came out of this work.

Most patients did see a specialist for their pulmonary hypertension, meaning that they saw either a cardiologist or a pulmonologist at least once for their pulmonary hypertension. However, a number of patients, nearly a quarter of patients, only saw a primary care provider and had no contact whatsoever with any relevant specialists. No cardiology visits, no pulmonary visits. Importantly, among a subset of patients who are on PH therapies, in this case, we define these as pulmonary vasodilators, about 8% of patients never saw a cardiologist, never saw a pulmonologist, were only cared for by primary care providers who we know don't have the knowledge and the expertise to be taking care of this very complicated and very complex disease.

Then, in terms of patients who saw a pulmonary hypertension expert over the study period, only about 8% of patients in the entire network saw a PH expert, which is not surprising given how few PH experts there are. But even among patients who are on therapies, even among patients who are on pulmonary vasodilators, fewer than half of those patients saw a pulmonary hypertension expert during our study period. In summary, I think a lot of these patients are being cared for by folks who don't have the expertise and the knowledge necessarily to provide the really complicated care that is required to care for these patients.

We already talked about how pulmonary hypertension experts are a limited resource. I think there definitely needs to be really concerted efforts in the PH community to try to build that capacity. I think that needs to happen probably on multiple levels. We need to improve the pipeline of providers going into this specialty. So, increasing the number of training programs, for example, that can train pulmonary hypertension experts. I think there also needs to be a building up of the PH expert centers to be able to accommodate more patients. So, that might be building more infrastructure, bringing in support staff who can help PH providers see more patients. At the end of the day, a PH expert only has so many hours in their clinic that they can see patients. We need to think a little bit more broadly about how we can provide high quality care to these patients, recognizing that PH experts are a limited resource and they can't see everybody.

So, does that mean creating some sort of hub and spoke type model where PH expert centers can help support maybe the cardiologists and the pulmonologists who don't have specific PH expertise in the community to help support them care for these patients in kind of a collaborative fashion?

Maybe some of this is patient preference with them wanting to stay kind of with their local provider, but I think more of it is just an awareness on the provider level that they ought to be referring these patients. I think we need to be disseminating clearer referral guidelines for folks in the community. For folks, meaning providers out in the community who are not within an expert center, I think we need broader efforts to try to disseminate to these folks who don't see pulmonary hypertension as often, what patients they need to be referring, and importantly, when they need to be referring.

We also know from prior work that patients, when they ultimately end up seeing a PH expert in one of these PH care centers, they often have very advanced disease at the time. They're often like what we call a functional class III or IV, meaning that they are very symptomatic, they're very short of breath. We know that patients, when they present late like that, it affects their long-term outcomes. I think we need do a better job of making sure that folks out in the community know when and how and for what patients they need to be referring into expert care.

Some of the other findings that we found from this specific study looking at care networks was we found significant kind of geographic patterns to referral patterns. When we looked visually at the networks of providers taking care of patients with pulmonary hypertension, and this tool that we use, Social Network Analysis, allows us to visually graph out what these networks look like. We found that patient sharing between providers tended to land pretty squarely within geographic regions of the state. So, providers within the Greater Boston area, for example, primary care providers, cardiologists, PH experts, they all shared patients really readily.

But then when you look out to the western part of the state, Western Massachusetts, which is much more rural, there was far fewer sharing of patients across providers across these geographic boundaries. We saw that visually in the network graphs that we created and we also saw that sort of quantitatively in some of the analytic work that we did. You can imagine that Massachusetts is a fairly small state. There are many PH expert centers or many PH experts. Most patients in our sample actually lived within 25 miles of their nearest PH center. This is a state that geographically is probably less challenging for patients to actually get to a PH expert or get to a PH care center.

You can imagine that there are a number of states across the country, a lot of rural areas across the country where there are zero PH centers or zero PH experts. So, you can imagine that some of these gaps in referrals to PH experts are probably even much more pronounced in states across the country that are more rural, in states that don't have as many PH experts and PH care centers.

I think the importance of getting patients into expert care cannot be understated. Not only do they get the expertise that comes with being seen by somebody who has specific training and experience in pulmonary hypertension, but they get all of the resources that come along with it. They get access to pharmacists, for example, who would have more knowledge about pulmonary hypertension therapies and can help these patients navigate the very complex issues with dealing with specialty care pharmacies, with dealing with insurance companies. They get access to clinical trials, they get access to other research opportunities. They get better connection to patient associations and other patient support groups where community providers, primary care providers and other specialists who don't see PH may not just have the awareness of all of these resources that are out there that are available to patients. So, I think patients who don't ultimately make it into a PH care center miss out on this whole host of opportunities, not just the opportunities to see an expert and to receive higher quality care.

This is a hard problem to fix. Obviously, we can't increase the number of PH providers and the PH care centers overnight. That will take time. It'll take effort on the provider level, on healthcare center levels, on health policy levels to address some of these gaps. I think we'll probably need a multifaceted approach to try to improve the access to expert pulmonary hypertension care and decrease some of these delays in care that we're seeing.

This includes investing in the pipeline of pulmonary hypertension experts, as we've already talked about. This might include expanding use of technology, expanding use of telehealth, for example, to try to reach some of these folks who are a little more remote, who may have geographic or other socioeconomic barriers to getting in to a PH expert. This may include developing AI tools, using the electronic health record within some of these centers outside of PH care centers to identify patients who are appropriate for referral and maybe flag for the provider to say, "Hey, this patient meets all the criteria for referral. You ought to think about getting them in." This might include building telementoring models so that PH experts can be mentoring providers out in the community to make sure that they're providing the highest quality of care. I think that we need to think outside the box. I think it's going to take a lot of creative efforts to try to tackle this really important problem of improving access and timeliness to pulmonary hypertension care.

My name is Dr. Kari Gillmeyer, and I'm aware that my patients are rare.\

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