In this episode of Stories of Care, Dr Shannon Novosad, Epidemic Intelligence Service Officer at CDC Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases discusses a recent Morbidity and Mortality Weekly Report on disparities in the rates of Staphylococcus aureus bloodstream infections in dialysis patients. In general, dialysis patients are 100 times more likely to get Staph aureus bloodstream infections. Race, ethnicity and socioeconomic factors affected infection rates and distribution among dialysis patients. Dr Novosad joins us to discuss the details of this report and its implication for patients and physicians.
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Welcome to Stories of Care, a podcast from the American Medical Association and CDC's Project Firstline. In this episode, we are joined by Dr Shannon Novosad, Team Lead of the Dialysis Safety Team at the Division of Healthcare Quality Promotion at the Centers for Disease Control and Prevention. She and her colleagues recently published data in the Morbidity and Mortality Weekly Report on rates of Staphylococcus aureus bloodstream infections in dialysis patients. They found that, in general, dialysis patients are 100 times more likely than other patients to get Staph aureus bloodstream infections. They also found that despite a lower rate of central venous catheter use, Hispanic dialysis patients had the highest risk of developing infection. Race, ethnicity and socioeconomic factors also affected infection rates and distribution. Dr Novosad joins us to discuss the details of this report and its implication for patients and physicians. To earn CME for listening, visit amafirstlinestories.org and click on the title of this episode to complete the quiz.
Megan Srinivas, MD: Well, hello, Dr Novosad. Thank you so much for joining us today.
Shannon Novosad, MD: Yeah, thanks. Thanks for having me. Excited to talk about this work with you guys.
Srinivas: Oh, we're excited to hear about it. I mean, there has been so many developments in the world of nephrology and equity and infection prevention. So first off, how did you get involved in looking at dialysis-related infections?
Novosad: Well, that's actually kind of interesting because my background is in pulmonary critical care medicine. I had long been interested in public health, even before I started medical school, even though I'm not actually sure I quite understood what public health was at that time. It just sounded like an interesting field.
But the more I learned about it, the more I really realized it was a great way to, you know, broaden what I was able to do kind of on an individual patient level. So that ultimately led me here to CDC, where I was working in the division of Healthcare Quality Promotion, which does a lot of different things in health care, but primarily is focusing on infection prevention across a variety of health care settings.
And through the variety of work they do, there is a team that focuses on dialysis and I was particularly drawn to that team given what I had seen previously, in my clinical work and the high risk of infections in patients on dialysis and the fact that I felt there was still a good amount of work to do.
And so, it was an area where I thought I could have some impact.
Srinivas: So, with dialysis infections, what was it that made you say, "Hey, I wanna look at the rate of dialysis infections from a racial equity standpoint?"
Novosad: Yeah, that was probably, what we were just seeing about this population of patients in general. Probably not a surprise to you or others.
You know, patients on dialysis in general are disproportionately represented, different racial and ethnic minority groups, which has been well documented for a long time. And there's also lots of disparities in terms of, you know, for example, which treatment modalities patients might get offered that have end-stage kidney disease.
Dialysis versus transplant and even the types of dialysis. And then things down to nephrology care prior to developing that. And so, I think it just piqued our interest because we knew that those disparities were there. But what there isn't a lot in the literature on is really infections.
Which we know obviously are a significant burden for these patients. And so, trying to understand if some of those same themes also meld over into the infections. We were interested in exploring more.
Srinivas: Well, and you touched on something that has actually been a personal passion of mine that I always discuss with people, was the whole interpretation and misunderstanding that we have around kidney functionality based on race.
And I know there have been a few studies that have been published on this, 2021 there was one study. But looking at how we have different values on interpreting what's a functioning kidney based on what race you are and how that might not be accurate. How the GFR for black patients is interpreted differently according to a lot of EMRs. But in reality that's not very accurate.
And so, we've been interpreting their GFR for so long and causing delays in care. How have you seen this manifested when you're talking about treatment modality inequities, you're talking about the ways that people can even access the types of care they get. Have you seen that manifest on your end?
Novosad: Yeah, so some of the disparities that we see are, again, I think related back to one, just, who's developing end-stage kidney disease and kind of the factors related to that. I think, thinking through some of the things that you mentioned, deciding when actually someone's going to get diagnosed with a certain level of kidney disease and then where they're gonna get referred to more advanced care to manage that and hopefully prevent progression or to start planning for different modalities.
Once someone has progressed to end stage disease, what modalities again that they're offered. So, it can range from in-center hemodialysis, which we traditionally think of. But there's also opportunities for dialysis at home with peritoneal dialysis and even home hemodialysis, which I think fewer people know about. And then a transplant.
So obviously thinking through those, I mean, there could be some reasons why someone has to do in-center dialysis, but it shouldn't also always be the default for people. I mean, there's obviously modalities that may provide better lifestyle and better other things for patients that may or may not be offered to patients or being planned for early enough that they can become a reality when they're needed more urgently.
Srinivas: When you control for other factors, what are some of the racialized inequities that you see when it comes to treatment modality offering, between PD versus in-center hemodialysis, home hemodialysis and transplant?
Novosad: Unfortunately, I will say our [CDC's] data is a bit limited.
[Based on other national data sources,] White patients, for example, have the lowest percentage of that group getting in-center hemodialysis, and the highest number of transplants. Around 50% of white patients with end-stage kidney disease will end up getting in-center hemo.
While closer to higher thirties or 40% will end up getting offered a transplant. Whereas for Black patients, about 70% of those prevalent patients will end up on in-center hemodialysis. And transplant numbers are more in the low twenties. And then there's other groups which, you know, we didn't focus on in some of our work just because we had like less data to look at the infections in them. But thinking back to these treatment modality disparities, Native Americans and Native Hawaiian and Pacific Islanders, definitely [have] disparities there as well.
Srinivas: Have we looked at this from a standpoint of controlling for the socioeconomic factors so we can say, hey, this is directly only different because of the racialized factor?
Novosad: We haven't in our work cuz we don't have that data here at CDC, but I think there has been some ongoing work on that in the past.
And I think as you'll see with our analysis, these relationships are so complex that, and it's hard to probably always have the exact right data to control for those factors that you wanna understand that I think it's hard to say a hundred percent the conclusions.
I think the end of the day they all find disparities, but the exact pathway is I think still undefined.
Srinivas: So I mean, it's great though that the CDC and so many organizations are really trying to focus on trying to fix this problem right now. When you're talking about the different modalities again, and so we're looking at it and seeing that disparities exist and the modalities you receive. What impact does this have on infections that are related to dialysis?
Are there certain modalities that have a higher risk of infection than others?
Novosad: So that's also interesting. So currently with our data at CDC, our surveillance is for bloodstream infections, primarily in outpatient hemodialysis. So, you'll also, that's kind of what our work has centered on.
But the different modalities have differing risks of, I would say, certain types of infections. So, for hemodialysis, you know, we're primarily focusing here on the bloodstream infections where vascular access plays a big factor in increasing that risk. But not to downplay also that peritoneal dialysis also has infection risk with peritonitis and we don't currently have national level surveillance data for peritonitis.
Srinivas: Of course. And some of your recent work has specifically looked at the linkage between that access type when it comes to dialysis and Staph aureus, right? Can you tell me a little bit about the link right there between Staph aureus and access type?
Novosad: Yeah, so I won't say that our findings are new for this, for sure.
So, we kind of undertook some of this current work to better understand that association between Staph aureus bloodstream infections specifically and different racial, ethnic, social determinants of health disparities and such. But given that we know vascular access is such a big risk factor for bloodstream infections in this patient group, we felt like there's no way you can go into an analysis like this without still looking at vascular access and thinking it through.
So, I think our findings were pretty similar to what we kind of already know about this risk. So, they're kind of three primary types of vascular access that patients on hemodialysis use. So, there's catheters, central venous catheters, which are typically tunneled. So, similar to what other patients may use, who need more long-term access like oncology patients or others.
Then there's fistulas and grafts. Both fistulas and grafts end up being connections kind of between the artery and the vein, creating like a high flow state for dialysis. The difference is fistulas is actually like a connection that's made using more of like a surgical procedure and no artificial material is used. Whereas a graft, an artificial material is used to make that connection.
So, we know that catheters have the highest risk. You know, probably not surprising given what we know about catheters and the fact that they're an artificial material implanted in your body and they stay there. High risk of contamination and all that. And then it kind of goes stepwise next to grafts and then next then to fistulas, which will have the lowest risk.
And again, I think makes sense, you know that grafts are lower than catheters, but then higher than fistulas. Cuz again, they're kind of that artificial material in a patient's body. So anytime you have anything like that in there, higher risk for infection. So, we saw, we actually used two different data sources for this current work.
And both of the sources that we found, found obviously a much higher risk of infection with catheters compared to fistulas. So, in one, the risk was about six times higher and then about two times higher with grafts compared to fistulas. So again, pretty similar to what we've seen in other data sources, but we made, wanted to make sure to include that.
Srinivas: No, that's, and that's an interesting breakdown. And do we see some of the disparities we were discussing before in even the choice of modality between venous catheter versus fistula versus graft?
Novosad: It's actually really interesting. I think going into trying to answer questions like this, about disparities in their association with infections, the natural assumption, and I think I've definitely had it in the past before I explored the data more, is to assume that a lot of this is driven by a big difference in the number of patients that have catheters or who have fistulas, and it's really not as far as we can tell. The best data that we currently have, I think to look at just what the numbers are nationally, is from USRDS, which is an NIH-funded system that collects data on both chronic kidney disease and end-stage kidney disease.
And they produce an annual report every year describing some of these factors. So, a lot of the data that we have on that we get from them. But in general, they describe both obviously initiation, the vascular access initiation of dialysis, so with incident patients and then more of the prevalent patients.
And on average, about 80% of most patients start dialysis with a catheter. And there are like there are small percentage differences between the groups, but there's not large percentage differences between the groups that you would think you would need to see to drive some of these differences.
And then when you move on to prevalent patients, the number on average we quote is that about 20% of these patients end up having a catheter, over time. And again, we actually don't see a lot of difference in those either. And actually, of the prevalent patients, the highest percentage is in white patients.
Again, it's only a couple of percentage points higher. But it's actually higher than in Black or Hispanic or other groups of patients. One of the biggest differences we actually see is, in Black patients on dialysis, a much higher use of graft than in other patients.
And what that means, it's hard to know, but that's like one of the most well documented, I'd say, differences between the racial groups there. So, I know I kind of said a lot on that, but I think it boils down to, we don't see big differences.
Srinivas: Yeah, no, that makes sense. So not really seeing much in the actual modality of receiving dialysis. How about when it comes to the actual manifestation of bloodstream infections?
Can you give us a little bit more information on the disparities you see there?
Novosad: We found the results on this really interesting. So, I think as we already mentioned, vascular access in general was the highest association we saw with infections. But even after controlling for that, we were able to see some differences amongst different groups.
So, particularly after controlling for vascular access, Hispanic ethnicity still had a 40% higher risk of Staph bloodstream infection. After controlling for vascular access to some other factors, we didn't see a difference with Black patients. But we did in the unadjusted rates, I probably should have started with that, but in the unadjusted rates, we did see a difference there, with Black patients and then Hispanic patients having a higher rate of infections.
And so then, again, we went to the multi-variable analysis and adjusting for it. That's when we still saw Hispanic ethnicity with that 40% higher risk. You might ask like, well, why do you present us the unadjusted rates? You know, when after you controlled for it, some of the differences went away.
But I mean, we thought the unadjusted rates were really important because those are, I mean, that's actually the real-life experience of people, right? Like at the end of the day, they probably don't care as much about us controlling away the factors and then saying it's not a risk. Like, so we know that these patients have the higher rate of bloodstream infections in general and that the factors behind it are probably pretty complex, especially given that we were able to control away some of that in the model.
Srinivas: What were some of the factors that you adjusted for that kind of changed the final outcome a little bit?
Novosad: We were limited to things that we were able to get in our surveillance data set.
So, there were some factors we weren't able to control for that we would've loved to be able to control for more, like insurance coverage and that kind of stuff. But what we were able to control for was the state of residence of the patients, their age, sex, and then the vascular access type.
Srinivas: And how about looking at socioeconomic status? Did you find any links that were to other factors outside of the racialized aspect?
Novosad: Yeah, so we were able to match the surveillance data that we had with census data to get a better idea of some of those factors that you're talking about there.
And what we did find was that there were higher, disproportionately higher numbers of patients on hemodialysis who had these Staph aureus bloodstream infections living in US census tracts that had higher poverty, more household crowding and then lower education levels. So able to hone in a little bit more on those factors there.
Which again, unfortunately we weren't able to control for in the model, but we were able to use the US census data to at least start to get a better handle on what some of these other factors might be.
Srinivas: These findings are so interesting, and it seems like there's so many implications for them already. What would you recommend, looking at the data?
How would you recommend that somebody in the clinical setting takes this data when they're looking at a patient and utilizes it in their decision making?
Novosad: Probably one, I think we need better data. I think we need better data on a national level, but I also think there's a role for individual organizations or facilities to think more closely about their own data and what they have access to and how they could actually use that to better understand some of these disparities and maybe help better target patients who might be at risk on a more micro level.
But then I think there's also the fact that we have strategies that we know work to prevent bloodstream infections in patients. And so, making sure that those are applied equitably amongst all patients and in all facilities, I think is a great place that people can start.
We have a group of practices at CDC specific to preventing bloodstream infections in dialysis called the Core Interventions. And so those have been shown in, and I know clinics who participated in projects implementing them to actually prevent bloodstream infections and have that sustained over time.
So again, making sure that things that we currently know work are implemented on a wide scale. I think it's also a great place to start. We can't explain all of the factors. But I think we can start exploring specifically how we educate these patients about infection risk and their access to resources and supplies to help prevent infections when they're outside the clinic as well.
So, making sure that any educational materials are culturally appropriate and targeted specifically for these patients. Especially for the higher risk we found in Hispanic patients, I think that might highlight a big gap that many of us could start working on now.
And then there's also better understanding, if some of the factors too are more related to lack of insurance and that type of stuff. Are they able to get access to supplies they would need to care for their vascular access site at home? Even just bandages, dressings to change and that kind of stuff.
Srinivas: What is the next study or the next areas that we really need to explore further to better understand all of these issues?
Novosad: I think we need to explore better ways to more systematically collect some of this other information that we want.
Obviously, we want consistent reporting of racial and ethnic kind of categorizations. But there's also all of these other factors that we're also talking about that are super important. And so, I think we need to explore how to collect that information, but also balance this with the burden of busy health care providers and organizations who already report a lot of data.
So, figuring out better ways to do that, hopefully maybe through some kind of automated reporting or something. So, I think that's like the pie in the sky dream to be able to capture this data in a systematic way without burdening providers.
Srinivas: The ultimate goal.
Novosad: The ultimate goal.
Obviously, goals like that take a while to achieve. Not that we shouldn't still be working towards them, but in the meantime, I don't think it should stop us from maybe working on a smaller scale. More in targeted areas or with individual facilities to try to gather data on some of these factors at the same time.
Srinivas: And so, with all these interesting findings from your study, you've been sharing it with different groups, including patients. Can you tell us a little bit about sharing your findings with patient groups?
Novosad: We had the opportunity to present this data and our findings to a patient group, which was really, I'd say really eye-opening for us to relate these findings to the patients.
I think one of the most interesting things was they immediately picked up on where the holes are in the data that we have. I think that, we discussed a little bit previously how we focus on white patients, Black patients and Hispanic patients, but we don't cover some of these other groups that have some of the disparities that we talked about in terms of treatment modalities and stuff.
And so, they immediately honed in on that, which I thought was very perceptive. And we, we talked through some of the challenges with that. And then they related a lot of their more first line experiences in the dialysis facility, particularly as it relates to infection prevention and seeing gaps in practice by the frontline staff. And kind of feeling like maybe they weren't sure where their place was in improving those practices and wanting to feel, I think, more empowered to speak up about those. And so, I also think that is a big area that these findings could be used to target is empowering patients themselves to speak up when they're in the dialysis facility, if they're seeing any gaps in practices.
And perhaps that education on how to do that might be something that needs to be more tailored to make sure it's culturally relevant and stuff for patients.
Srinivas: What type of group was this? Was this a very diverse group? Was it all people getting in-center hemodialysis? Was it a mix of modalities?
Novosad: It was a mix. It was a group, actually, that works with the ESRD networks, which are funded by CMS to help do quality improvement in dialysis facilities. So, I will say it is a highly motivated group of patients who is interested in, you know, affecting change in their facilities and across kind of the treatment modalities for ESKD.
But yeah, a variety of patients. So, some are still getting in-center hemodialysis. Some have had transplants, PD, so kind of across the board, which is also nice to get that kind of broad perspective.
Srinivas: It's so interesting to see that just sharing the data created a whole new avenue for study, potentially, with trying to create more education around something that hadn't been the center focus before.
Novosad: We have a little bit on our side worked in the past on thinking through how we can better increase patient engagement in these activities. But I don't think we had ever thought about it kind of through this other focus that, well, maybe we created a resource in general to improve patient engagement.
Maybe it's not actually getting to the groups of patients who actually, who need that. Or maybe it's not tailored in the right way or in the right language even. And so, I think it's given us a lot to think.
Srinivas: So, when you're talking about the core prevention strategies, just things that clinicians can apply, after hearing all the information you've shared from your studies, what are some of the biggest and most effective strategies there that you can tell our listeners if they're taking care of a patient, these are the things you wanna make sure you do.
Novosad: We call 'em the, again, the Core Interventions from CDC, and they're again, a group of interventions that were studied and implemented as a bundle to better understand their role in preventing infections in dialysis. And this was work that was done several years ago.
And it was inspired a bit by the success of bundles in the inpatient setting to prevent CLABSIs [central line associated bloodstream infections]. And so given you know, what we've already talked about and what we know about the high burden of bloodstream infections in this group the thought was like, well, why wouldn't some kind of approach like this also work in the outpatient setting?
They involve different types of things. So, for example, using chlorhexidine for skin antisepsis, which, which sounds maybe like low hanging fruit, but particularly when these were implemented, it may or may not have been actually the most common agent that was used in dialysis at that time.
Catheter hub disinfection is also heavily emphasized, and then there's a lot in there about actually working with staff to better understand what's going on with infections in their facility. So doing surveillance and feedback for infections. Again, really emphasizing that feedback to the frontline clinical staff about what's happening.
Doing observations for different IPC practices like hand hygiene and catheter and other vascular access care, staff education and competency, patient education, catheter reduction. I probably missed a few, but I think you got, you can probably see kind of generally where we're going with this.
So, some of these practices, you may think of them even more as just standard of care now in dialysis, but they weren't always. And a dialysis unit is a very, very busy place with lots of competing activities going on. So, always good to get back to what we wanna call the basics there too, to prevent infections cuz I mean they're what we know works definitely the best right now.
Srinivas: Well, this has been absolutely fascinating. If you were to tell our listeners what one of the biggest things you want them to learn, one of the things that you want them to take away from what we talked about today, what would that be?
Novosad: The relationship between these Staph bloodstream infections in dialysis patients is very complex. And we talk a lot about data and the factors behind it. But we were able to show that there were associations with some specific factors, again Hispanic ethnicity to throw out there again and some of those socioeconomic factors that we discussed.
So, I think the biggest thing is for them to understand that while we still have more to learn, we think we've identified a starting place here that we can all start focusing efforts on and learning about.
Srinivas: Well, that's awesome. At least we have a place to go from here. We have some information to start with and ways in which we can improve our patient care every day.
Thank you so much for sharing your knowledge, your experience, your expertise, and all the great work that you're doing in this area.
Novosad: Yeah, thanks so much. I enjoyed the discussion.
Stories of Care is a publication of the AMA and CDC's Project Firstline. Project Firstline is a national infection control training collaborative, working to provide all health care professionals with the foundational infection control knowledge they need and deserve to protect themselves, their patients, their coworkers, and their communities. For more information, trainings and other infection control resources, visit CDC.gov/projectfirstline and AMAfirstline.org.
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