Serum creatinine and cystatin C-based index can be a screening biomarker for sarcopenia in older population

Considering the clinical impact of sarcopenia, it would be interesting to get a rapid and sensible screening tool. We conducted a cross-sectional study with the motive to use an index based on serum creatinine and cystatin C to screen sarcopenia in older people in outpatient settings.

100 participants above the age of 65 years were recruited from the outpatient department of Geriatric medicine of a tertiary care hospital in India. Muscle mass, muscle strength and physical performance were measured by DXA scan, hand-held dynamometer and 4 m gait speed, respectively. Sarcopenia was identified using Asian working group of sarcopenia (AWGS) criteria. Serum creatinine and cystatin C were measured for all participants. Serum creatinine/cystatin C ratio and biochemical total body muscle mass index (TBMM) were calculated and its association was checked with sarcopenia.

The prevalence of sarcopenia was 53%. Mean serum creatinine/cystatin C ratio was 74.79 ± 24.91. It was not significantly associated with sarcopenia. Mean biochemical TBMM index of participants was 36.40 ± 7.88 (males-38.77 ± 7.72, females-31.22 ± 5.13). The lower value of biochemical TBMM index was significantly associated with an increased risk of sarcopenia (p < 0.01). Cut-off value of 40.9 in males (sensitivity-79.41%; specificity-61.76%) and 32.2 in females (sensitivity-78.95%; specificity-66.67%) was proposed for identification of sarcopenia.

Out of the two indices, only low biochemical total body muscle mass index is significantly associated with sarcopenia and a value of less than 40.9 in males and 32.2 in females can be used to screen sarcopenia in older people.