Loss of muscle mass and strength — known as sarcopenia — may affect up to 55% of patients with systemic sclerosis (SSc), a study suggests.

Moreover, sarcopenia was found to be associated with several clinical and nutritional parameters of disease severity.

The study, “ Sarcopenia in systemic sclerosis: the impact of nutritional, clinical, and laboratory features ” was published in the journal Rheumatology International.

People with rheumatic diseases — including rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, systemic lupus erythematosus, and fibromyalgia — are more prone to develop sarcopenia, the loss of muscle mass and strength that may progress to disability.

SSc is a chronic autoimmune rheumatic disease, and two recent studies have estimated a prevalence of 20.7% to 22.5% of sarcopenia among SSc patients. In one of the studies, sarcopenia was associated with duration and severity of the disease, namely lung and skin involvement.

Now, a team led by researchers at the University of Siena, Italy, evaluated the presence of sarcopenia in 62 SSc patients — 50 with limited cutaneous SSc and 12 with diffuse cutaneous SSc — using two common tools to assess muscle wasting, the hand grip strength (HGS) and the Relative Skeletal Mass Index (RSMI) test.

The researchers also evaluated clinical and lab parameters, as well as patients’ nutritional status, including lean body mass (LBM) and vitamin D levels.

According to RSMI, sarcopenia is defined as a score below 7.26 kilograms per square meter in men, and below 5.50 in women. According to these values, researchers found that 26 SSc patients (42%) in the cohort analyzed were positive for sarcopenia.

Age, as well as malnutrition and LBM, influenced the prevalence of sarcopenia. Longer disease duration, and higher scores in the modified Rodnan skin score (mRSS), as well as increased inflammation (as measured by the erythrocyte sedimentation rate) were also associated with sarcopenia.

“mRSS was on an average four times higher in sarcopenic cohort than in non-sarcopenic one,” researchers stated.

Researchers also found that the presence of antinuclear antibodies — those reacting against proteins inside cells — and a reduction in the lungs’ diffusing capacity for carbon monoxide (DLCO) — a test of the lungs’ capacity to transfer oxygen from the air sacs into the blood — also correlated with sarcopenia.

Quality of life, measured by the Short Form Health Survey (SF-36), was significantly lower in sarcopenic SSc patients.

Using the HGS, whose scores below 30 identify sarcopenia in men and below 20 in women, the prevalence of sarcopenia in this SSc population was 54.8% (34 patients affected).

The team also emphasized that “all patients with [diffuse cutaneous] SSc resulted [as] sarcopenic according to the HGS index.”

Overall, “by using both RSMI and HGS to assess sarcopenia in SSc, the results of this study demonstrated that this condition correlates with different nutritional, clinical, and biochemical parameters associated with the worsening of the disease,” the team concluded.