Lower levels of serum sclerostin (SOST) were significantly associated with increased risk of lung exacerbations and hospitalizations in adults with chronic obstructive pulmonary disease (COPD), based on data from 139 individuals.
COPD exacerbations contribute to poorer prognosis and diminished quality of life, but many potential triggers of these exacerbations, including serum biomarkers, have not been well studied, wrote Carlos A. Amado, MD, of Hospital Universitario Marqués de Valdecilla, Santander, Spain, and colleagues.
These biomarkers include sclerostin, which is associated with bone metabolism and may play a role in “muscle-bone crosstalk,” thereby impacting lung function, they said.
In a study published in Pulmonology, the researchers recruited 139 adult outpatients with stable COPD and normal kidney function who were treated at a single center. The patients were followed for 12 months after study enrollment and a baseline assessment of serum SOST, bone metabolism parameters, body composition, clinical characteristics, and lung function. The mean age of the participants was 65.8 years, and 71% were men. Notably, 41.7% of the participants were current smokers. Body composition was assessed using fat-free mass index (FFMI), and lung function was assessed using forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC).
A total of 55 patients had SOST levels of 20 pmol/L at baseline, and 84 had SOST levels greater than 20 pmol/L. In a multivariate analysis, only age and FFMI were positively correlated with SOST levels (beta = 0.264 and beta = 1.241, respectively).
Patients in the lower tertile of SOST levels had a significantly higher risk of moderate COPD exacerbation (hazard ratio [HR] 2.015, P = .017) and hospital admission related to COPD (HR 5.142, P = .015) compared to the other patients. Also in a multivariate analysis, low levels of SOST were independently associated with FFMI (odds ratio [OR] 1.936, P = .004) but not with any of the other variables.
“We can only speculate about the possible causes and effects of low SOST in COPD,” the researchers wrote in their discussion. However, “We found that SOST and FFMI were positively associated in patients with COPD; therefore, lower levels of circulating SOST might reflect sarcopenia,” they noted. Low levels of muscle mass are associated with COPD exacerbations, they added.
The study findings were limited by several factors, including the use of patients from only one center, and the high prevalence of hypovitaminosis D in the study population. The study also was not designed to show causality, the researchers said.
However, the results were strengthened by their specific design and overall well-selected population, as well as the evaluation of bone metabolism, they said.
The study offers the first evidence of an association between SOST and clinical outcomes in COPD, “and may have a role as a biomarker to evaluate the risk of exacerbation and hospitalization in COPD,” but more research is needed in other populations to fully evaluate the therapeutic aspects of the study findings, the researchers concluded.
The study was supported by the Instituto de Investigación Sanitaria of Cantabria. The researchers disclosed no financial conflicts.
Pulmonology. Published online August 11, 2022. Full Text.
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