Muscle Loss Common in Women in Long-term Remission
Loss of muscle mass, also known as sarcopenia, is common among people with Cushing’s syndrome in long-term remission, and is associated with a poorer quality of life, a study reported.
Its researchers also found the Sarcopenia Index, a blood test that can be used to estimate a patient’s muscle mass, may serve as a way of identifying Cushing’s patients at risk of developing sarcopenia.
The study, “Prevalence of sarcopenia after remission of hypercortisolism and its impact on HRQoL,” was published in the journal Clinical Endocrinology.
Around 70% of Cushing’s syndrome patients experience muscle weakness, and researchers have observed more muscle loss in these people, relative to healthy people of a similar body mass index (BMI; a measure of body fat).
Even effectively “cured” women with this syndrome — those in long-term remission — often show poor muscular performance, despite maintaining the same amount of muscle mass.
Just how prevalent sarcopenia is among those in long-term remission and how it impacts their quality of life remains an open question. To answer this, clinicians needed a biomarker capable of indicating which people might be at a higher risk of sarcopenia.
Researchers in Spain, along with colleagues in Belgium and the U.K., evaluated changes in muscle function in 36 women who had been in remission from Cushing’s for a minimum of three years.
They compared their findings in these patients to 36 women of approximately the same age, BMI, menopausal status, and level of physical activity who never had the disease (controls).
They also tested whether the Sarcopenia Index reliably correlated with their findings, to determine its potential usefulness as a sarcopenia biomarker.
Overall, sarcopenia occurred more often in women who were in remission from Cushing’s than in those who never had the disorder (19% vs. 3%).
Investigators also found that sarcopenia was associated with a poorer quality of life, as measured by the Sarcopenia Quality of Life (SarQoL), the Cushing’s Disease Quality of Life Instrument (CushingQoL), and the Short-Form 36-Item (SF-36) questionnaire, all standard scales used to assess life quality.
Participants with sarcopenia reported more pain, easy bruising, greater concerns about their physical appearance, and generally worse physical functioning on the CushingQoL and the SF-36, compared with patients without sarcopenia.
Patients with sarcopenia also had lower Sarcopenia Index scores — indicating poorer muscle quality and lower muscle mass — compared with those without sarcopenia (71 vs. 77).
Low Sarcopenia Index scores were also found to be associated with a greater muscle fat content, as well as with several measures of physical disability on the SarQoL scale, including worse performance on the 30-second chair stand test, slower walking speed, and lower scores in other quality-of-life measures related to muscle weakness.
Based on these findings, researchers assigned a Sarcopenia Index cutoff value of 72 to distinguish patients with sarcopenia from those without it. Considering the defined threshold, researchers estimated the Sarcopenia Index was able to correctly identify Cushing’s patients at risk of developing sarcopenia with a sensitivity of 73% and a specificity of 90%.
Of note, sensitivity reflects a test’s ability of correctly identifying people with a condition (true positives), while specificity is its ability to correctly identify individuals who do not have a condition (true negatives).
“Future prospective studies are needed to confirm the usefulness of the [Sarcopenia Index] in the clinical setting,” the researchers wrote, “to evaluate physical function in [Cushing’s] patients at every stage of the disease, and monitor the responsiveness to specific treatments aimed at improving muscle performance.”
Sarcopenia is both common in Cushing’s syndrome patients in long-term remission, and is quality of life affecting, the team concluded, suggesting that physical activity programs be part of these patients’ ongoing care.
“The Sarcopenia Index is a potential biomarker allowing clinicians to identify patients at high risk of muscle dysfunction,” they added.