Skeletal Muscle Adiposity and Lung Function Trajectory in the Severe Asthma Research Program
In this video, Matthew C. Tattersall, DO, MS, provides an overview of the results from the study “Skeletal Muscle Adiposity and Lung Function Trajectory in the Severe Asthma Research Program,” including the association of baseline paraspinal muscle density and lung function trajectory over a period of 5 years and stratified by sex.
Additiional Resource:
Tattersall MC, Lee KE, Tsuchiya N, et al. Skeletal muscle adiposity and lung function trajectory in the severe asthma research program. Am J Respir Crit Care Med. 2023;207(4):475-484. doi:10.1164/rccm.202203-0597OC
Matthew C. Tattersall, DO, MS, is an assistant professor of medicine in the Division of Cardiovascular Medicine in the Department of Medicine at the University of Wisconsin hospitals and clinics (Madison, Wisconsin).
TRANSCRIPTION:
Matthew C. Tattersall, DO, MS: My name is Dr Matthew Tattersall. I am an assistant professor of medicine at the University of Wisconsin at Madison, and I'm a general cardiologist and a preventive cardiologist. I'm the associate director of the preventive cardiology program here.
Consultant360: Please provide an overview of this study.
Yeah, so lung function decline in asthma is a feared result of the disease and is associated with increased morbidity mortality. So, while the pulmonary predictors of lung function decline in asthma have been described previously, the extrapulmonary measures are largely unknown. And skeletal muscles play a vital role in lung function and can directly influence lung function. But they can also serve as a cardiometabolic marker, which can, in turn, affect lung function.
Dr Tattersall: So, what we really wanted to do is determine whether skeletal muscle adiposity predicts longitudinal lung function trajectory in asthma. So, the severe asthma research program, or SARP, is a unique National Heart Lung Blood Institute-funded prospective cohort study, of enrolling patients from over nine clinical academic centers in the United States, all with significant amounts of asthma. So, we evaluated baseline CT scans of the chest among 219 participants who received baseline imaging, and we measured the per-muscle density, which is a reproducible metric of skeletal muscle adiposity. And we compared these participants with asthma to healthy controls recruited from the community. Then we wanted to evaluate how the paraspinal muscle density predicts lung function trajectory over a median of five years. So, basically, we looked at this paraspinal muscle density as a marker of tissue adiposity. So, how much fat tissue is within the muscle, and how does this influence lung function trajectory over a median of five years?
C360: What were the results and how do they impact clinical practice?
Dr Tattersall: Well, so we found four major results. First, the paraspinal muscle density was lower or worse, meaning there was more muscle adiposity among both men and women with asthma compared to the healthy controls. Second, among participants with asthma, women had lower paraspinal muscle density or more adipose tissue within the muscle compared to men. Third, among women with asthma, the baseline paraspinal muscle density was a strong and independent predictor of lung function trajectory over a median of five years, meaning the lower or the worse paraspinal muscle density measure or the more adipose tissue in the muscle, the more lung function decline over those five years. And finally, these results remain consistent and robust, even adjusting for markers of inflammation and glucose metabolism, which suggests that this paraspinal muscle density marker may be an early barometer of metabolic health.
C360: What is next for research on this topic?
Dr Tattersall: Well, there's a lot there unanswered regarding the paraspinal muscle density. One thing that we don't know is whether structured exercise programs can modify the paraspinal muscle density composition, improve it, and whether, in turn, this would improve lung function trajectory among asthmatics and even among non-asthmatics.
C360: What are the overall take-home messages from this study?
Dr Tattersall: Yeah, so paraspinal muscle density which is an easily obtainable measure of skeletal muscle adiposity, it's also very reproducible and is lower among participants or patients with asthma compared to controls. And its baseline measure robustly predicts long function trajectory over a median of five years, more so in women than men.