Research hints that severe cases linked to persistent pain

Host Amber Smith: Upstate Medical University in Syracuse, New York, invites you to be The Informed Patient with the podcast that features experts from Central New York's only academic medical center. I'm your host, Amber Smith.

Does the severity of a COVID-19 infection predict the development of long COVID conditions, such as chronic pain?

Upstate researchers were curious to find out, and today I'm talking with Dr. Jamie Romeiser, who led research on this topic. She's an assistant professor of public health and preventive medicine at Upstate.

Welcome to "The Informed Patient," Dr. Romeiser.

Jamie Romeiser, PhD: Thank you so much for having me, Amber.

Host Amber Smith: So you set out to determine if COVID-19 severity might be a new risk factor for chronic pain. Is that right?

Jamie Romeiser, PhD: Yes, that's correct. So, when we think about chronic pain, there's a pretty well-known slate of risk factors or characteristics that might put you at a higher risk for developing chronic pain.

And some of these factors might include increasing age or having certain comorbid (simultaneous) conditions, like arthritis or a higher BMI (body mass index) or different socioeconomic factors, even. So what we wanted to know was, above and beyond all of those types of factors, if a severe COVID infection might actually be an emerging new risk factor for chronic pain.

Host Amber Smith: So what inspired you to look into this?

Jamie Romeiser, PhD: Well, it was a combination of things. And if I'm going to be completely honest, I think my initial curiosity was piqued sometime back in October of last year when I was listening to a story on NPR about long COVID. But since that time, it's really becoming recognized that some individuals who have had a COVID-19 infection, they may experience long COVID, and so long COVID is described as having symptoms that persist for longer than three months, and that didn't exist prior to the virus.

And, for example, frequently we think about fatigue or memory problems or even brain fog when we think about long COVID.

But after digging into the (medical) literature a little bit more, a commonly reported lingering symptom is actually pain. And this could be musculoskeletal pain, it could be pain in your joints or in your muscles or even neurological pain. So, when I started looking into this a little bit, at relatively the same time, I was part of a few conversations with people who were actually experiencing this lingering pain after a COVID infection.

So, we thought that, you know what, this might be the right time to look at this at, potentially, a population level. So, chronic pain itself is such a huge public health issue, and if it seems like COVID is contributing to this public health issue, then we really need to be aware of it.

Host Amber Smith: What did you think you might find?

Jamie Romeiser, PhD: Well, there really were a handful of studies that found new instances for chronic of pain after a severe infection. So, we thought we might be able to see something similar at the population level, but truly we didn't really know.

Host Amber Smith: So is there, are you saying that there are previous viruses that have been connected to chronic pain before COVID?

Jamie Romeiser, PhD: There might be. But in terms of the smaller studies that we were looking at, they were actually more small, clinical-based studies that looked at severe infections from COVID and then looked at new instances of chronic pain.

Host Amber Smith: I see. Well, can you tell us about the data that you used in your study?

Jamie Romeiser, PhD: Sure.

So, in terms of where the data came from, we used data from the National Health Interview Survey. So, this is a survey that was collected in 2021, but it's been collected since somewhere around the 1950s, every year. This is a survey that's collected from the National Center for Health Statistics, which is part of the CDC (Centers for Disease Control and Prevention).

So, one of the main objectives of this survey is to monitor that overall health of the United States' population. So there's really a great deal of effort that's put into this data and the survey itself and ensuring that it's nationally representative of the United States' population.

Host Amber Smith: So, how many people were represented in the data that you worked with?

Jamie Romeiser, PhD: Well, in our study we used that 2021 data, and after we applied a certain inclusion criteria, we had over 15,000 people who met this criteria. But because of the way that this survey is collected -- so, it's collected to represent a national population -- you can actually take that number and extrapolate it to that population level.

So in a way, our study represented over 135 million people in the U.S.

Host Amber Smith: Did it include as many people with mild COVID infections as with severe infections? And did it include people with no infection of COVID?

Jamie Romeiser, PhD: It included all three, but these groups were really different, proportionally speaking.

So, the majority of people in our 15,000-person sample, actually 76% of those, reported never testing positive for COVID infection, which was a little bit surprising, but then, when you think back, this was collected in 2021, so it's easy to lose time between the beginning of the pandemic and now.

But when you talk about the rest of the people who did report having an infection, this was broken down then into people who reported either no symptoms or mild symptoms, and so that group made up about 11% of our sample. And then those who had a moderate or severe infection made up about 13%.

Host Amber Smith: And how did you define pain in the study?

Jamie Romeiser, PhD: Chronic pain in general is defined as pain that lasts for over three months. This is different from acute pain, which is usually from an injury that goes away. Chronic pain can be there either all the time, or it could potentially come and go, but it still occurs on most days.

So, in this survey, participants were asked, "In the past three months, how often have you had pain?" And people responded. Those who did respond at "most days" or "every day" met that definition of chronic pain. And the people who reported either never having pain or maybe just pain on some days, they were classified as not having chronic pain.

Host Amber Smith: So, how did you tell if it was chronic pain that was there before COVID or if it was caused by something else?

Jamie Romeiser, PhD: That's one of the difficulties of cross-sectional data, and that's one of the big limitations, for this particular study, is that we can't necessarily distinguish that particular time window.

The best thing that we can do is potentially control for that whole slate of risk factors, or all of those conditions that very likely predict your chance of getting a chronic pain and then isolate really what's happening with a severe COVID infection.

Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith.

I'm talking with Dr. Jamie Romeiser. She's an assistant professor of public health and preventive medicine at Upstate, and she's done research on COVID-19 and its connection to chronic pain.

So let's go over some of the results. How did the severely infected compare with the never infected?

Jamie Romeiser, PhD: We ran these results in a couple different ways, so let me just quick tell you about the information that I'm going to present you.

We first looked at this in simply prevalence of chronic pain. So how common was this in our different groups here, in our three different groups? And then the next thing we did was to try to control for all of those risk factors and say, well above and beyond, what happens here, with a severe infection.

And then we did this third technique, which was actually matching. So we were able to create these three different groups that were really matched on their risk profiles so that we were more comparing apples to apples to apples, in a way.

So, when it comes to that first type of analysis, just looking at how common pain was in the severe group versus the never-infected group, in that broad a scope, we found that about 25% of those who had a severe infection reported also having chronic pain, whereas only 19% of those who never experienced that COVID infection reported chronic pain. So that's a difference of about 6%, which might seem small, but when you scale that to that population level, we're talking about, like, over 3 million people, so, 3 million additional people, when you take a look at this data and you control for all of those factors that usually predict chronic pain.

So, in that adjusted analysis, what we found was that the odds of chronic pain were 20% higher in the severe-infection group compared to that never-infected group.

And then when you take that analysis one more step further, and when we look at these matched groups, so matching people on all of those factors, now what is that isolated effect of COVID? And at least for the severe group, we did see about 45% higher odds of chronic pain in that severe group versus the never group.

Host Amber Smith: That does sound significant. Did your study show that COVID-19 causes chronic pain?

Jamie Romeiser, PhD: We're not able to establish that causal link with this data, and that's a really important clarification for the studies, that because of the way that the data are collected, that is a limitation.

But, after we did the matching component, after we were able to try our best to create these balanced groups, we did see that association. And so we really do think that there's a signal there.

Host Amber Smith: Well, let me ask you a little bit more about the pain that was described. Did you notice anything in common in how people described their pain?

Jamie Romeiser, PhD: Unfortunately, we weren't able to look at that specific distribution of types of pain here. We were kind of limited to what was collected within the survey, but in general, from previous literature, what we think is, this is mostly joint pain and muscle pain, pain in your hands, headaches, that type of thing.

And this type of distribution of pain should certainly be something that's examined in future studies of long COVID.

Host Amber Smith: Did you ask or look at other long COVID symptoms?

Jamie Romeiser, PhD: In our study, we didn't. So, we just focused specifically on chronic pain. But again, there are certainly other opportunities in the future to investigate those outcomes.

Host Amber Smith: Now, I know you're a PhD, not an MD, but from your research, if moderate COVID-19 infection may increase a person's risk of developing chronic pain, are there any lessons to be learned from that?

Jamie Romeiser, PhD: I think so. You know, as the broader literature stands, it does seem like anybody who has had COVID could develop long COVID.

But from this study and many other studies, it really does appear that that risk is increased for those who have had that more severe infection. So, that being said, it's really important that those who are most susceptible to that severe infection, so those who are older, those who have serious medical conditions, that they try to reduce their risk of that severe infection as much as they possibly can.

Host Amber Smith: So, trying not to get infected with COVID in the first place.

Jamie Romeiser, PhD: Right. Something that you can do to reduce that risk would be not only knowing your personal level of risk, but I'd say be aware of the general risk level in your community because that really does change over time, and you might moderate your behavior a bit due to this community risk.

And I will say to date that vaccinations still remain one of the strongest defenses against developing severe COVID infections and those subsequent long-haul symptoms, like chronic pain. The efficacy of these vaccines really does remain higher against those severe infections compared to the mild infections, but they can wane over time with all these emerging variants, so it's important to be up to date on your boosters. It's still an essential component of prevention against severe infection.

Host Amber Smith: In your research, did you come across any indication that the chronic pain that develops after COVID-19 is any different in terms of symptoms or in how it's treated than chronic pain caused by an injury or something else?

Jamie Romeiser, PhD: As you pointed out earlier, I'm a PhD and not an MD. I'm not exactly sure about that underlying biological mechanism of long COVID and those pain manifestations, but what I do know is that chronic pain and the way that people respond to treatment of chronic pain is really different in every individual.

And so it would be important to speak to your primary care physician or pain specialist to discuss those treatment options.

But we do look forward to more research coming out about this in the future.

Host Amber Smith: Thank you for making time for this interview, Dr. Romeiser.

Jamie Romeiser, PhD: Thank you so much for having me.

Host Amber Smith: My guest has been assistant professor of public health and preventive medicine Jamie Romeiser. " The Informed Patient" is a podcast covering health, science and medicine, brought to you by Upstate Medical University in Syracuse, New York, and produced by Jim Howe. Find our archive of previous episodes at upstate.edu/informed.

This is your host, Amber Smith, thanking you for listening. Does the severity of a COVID-19 infection predict the development of long-COVID conditions, such as chronic pain? Upstate researchers studied this question, using a database collected from thousands of people. Jamie Romeiser, PhD, who led the research, explains the findings. Romeiser is an assistant professor of public health and preventive medicine at Upstate.