Men experiencing sarcopenia who also have been diagnosed with chronic obstructive pulmonary disease (COPD) are at a significantly higher risk of developing osteopenia and osteoporosis than are men who do not suffer from COPD, according to a new study published in Chest.
“Muscle depletion has been considered a risk factor for low [bone mineral density (BMD)] in the healthy general population [but] data on the association between sarcopenia and osteopenia/osteoporosis in COPD patients are lacking,” wrote the investigators of the study, coauthored by Moo Suk Park, MD , of Yonsei University in Seoul, South Korea ( Chest. 2017 Jan. doi: 10.1016/j.chest.2016.12.006 ).
“Although previous studies showed that loss of fat-free mass (FFM) was related to BMD loss in COPD patients, it is difficult to know the genuine relationship between skeletal muscle mass and BMD because whole body FFM contains a large proportion of water-retaining organs and nonmuscle soft tissue,” the authors continued.
The investigators examined data from the Korean National Health and Nutritional Examination Survey (KNHANES), looking for men at least 20 years of age with COPD who had both pulmonary function test and the dual-energy x-ray absorptiometry (DXA) performed on them during the years 2008-2011. A total of 864 men were deemed eligible for inclusion, and were scored for sarcopenia and osteopenia/osteoporosis; the former was assessed via the appendicular skeletal mass index (ASMI), with the latter done via T-score.
“Sarcopenia and presarcopenia were defined according to the presence of ASMI values that were less than two standard deviations (SDs) and between 2SDs and 1SD, respectively, below the mean value of a young male reference group aged 20-39 years,” according to the investigators. “Osteoporosis, osteopenia, and normal BMD were identified according to the lowest T-score of the three measured locations and were defined according to the World Health Organization criteria.”
Results showed that sarcopenia in men with COPD led to a higher risk of having low BMD, with an odds ratio of 2.31 (95% CI 1.53-3.46, P less than .001). A higher percentage of men categorized as having presarcopenia had low BMD (157/445, 35.53%), compared to just 15.4% (15/332) of those with normal BMD (P less than .001). Similarly, while only 1.2% (4/332) of those with sarcopenia had normal BMD, 8.3% (37/445) had low BMD (P = .017). The ASMI to T-score ratio of 0.408 (P less than .001) indicated a significant association between appendicular skeletal muscle mass and BMD.
“This study affirms the systemic nature of COPD, as it is not merely a disease that manifests as breathlessness and other respiratory complaints, but affects many aspects of a patient’s functionality and overall health,” explained Eric J. Gartman, MD , of Brown University, Providence, Rhode Island. “In clinical practice, this study reminds us that we need to consider these other issues in a COPD patient’s care, since the outcomes from these problems (e.g. hip fractures) can be devastating.”
Echoing those thoughts in a separate interview, Vera De Palo, MD – also at Brown University – explained that this study will help health care providers “deepen our understanding of these associations and contributing factors, [and] it may lead to targeted interventions that help to slow the sarcopenia that contributes to the dysfunction and fragility in our patients.”
A critical limitation of this study, however, is the sample population, according to Dr. Gartman. “It is solely made up of Korean men, thus somewhat limiting the generalizability to a larger population [and] especially to women, given that there are several other considerations surrounding effects on BMD.”
No funding sources were disclosed. The authors reported no conflicts of interest.