An exploratory multi-biomarker panel including fecal calprotectin, Brain-Derived Neurotrophic Factor, Fibroblast-Growth Factor-21 and irisin shows poor diagnostic accuracy for detecting probable sarcopenia in community-dwelling older persons

BACKGROUNDS: Serum and fecal biological markers that reflect underlying drivers of sarcopenia, may aid in novel predictive or diagnostic tools for sarcopenia. AIMS: To explore the potential of five specific myokines and fecal calprotectin (fCPT) as biomarkers for diagnosing the presence of at least probable sarcopenia in community-dwelling individuals aged ≥ 65 years. METHODS: This cross-sectional, exploratory study included 156 participants (median age 73y), of whom 59 (20♂, 39♀) had at least probable sarcopenia per EWGSOP2 criteria, and 97 (33♂, 64♀) controls. Myostatin, irisin, Brain-Derived Neurotrophic Factor (BDNF), Insulin-like Growth Factor-1 (IGF-1), Fibroblast Growth Factor-21 (FGF-21), and fCPT were measured using Enzyme-Linked ImmunoSorbent Assay (ELISA). Muscle mass and function were assessed via appendicular lean mass (ALM), hand grip strength (HGS), 5-time chair stand test (CST), gait speed, and the Short Physical Performance Battery (SPPB). Linear and logistic regressions analyses were performed. Diagnostic accuracy was evaluated using Area’s Under the Curve (AUC). RESULTS: Participants with fCPT < 50 µg/g walked faster than those with fCPT ≥ 200 µg/g. Higher fCPT associated with slower gait speed (β: -0.003; 95% CI [-0.001; -0.00002]), while IGF-1 associated with higher HGS (β: 0.077; 95% CI [0.039; 0.116]). BDNF alone diagnosed at least having probable sarcopenia (AUC: 0.63; sensitivity 53%, specificity 71%). A multi-biomarker panel comprising BDNF, irisin, FGF-21 and fCPT modestly improved accuracy (AUC: 0.71; sensitivity 64%, specificity 77%), but this improvement was not statistically significant compared with the single biomarkers BDNF (p = 0.330) and fCPT (p = 0.180). DISCUSSION: The multi-biomarker panel significantly diagnosed at least having probable sarcopenia, but with high false negative (36%) and positive (23%) rates, respectively. CONCLUSION: The clinical relevance of this specific multi-biomarker panel may be limited due to moderate diagnostic accuracy. Validation in larger cohorts is needed.