B108-14 Sex-stratified Reliability of SARC-F in Predicting Low Muscle Mass or Phase Angle in COPD

Background

Sarcopenia (i.e., skeletal muscle loss) is common in chronic obstructive pulmonary disease (COPD) and is a major contributor to adverse clinical outcomes. Questionnaire-based screening tools such as the Strength, Assistance with walking, Rise from a chair, Climb stairs, and Falls (SARC-F) rely on self-reported symptoms and may fail to accurately identify sarcopenia when compared with objective measures. We sought to determine whether the SARC-F questionnaire could predict sarcopenia defined by low skeletal muscle mass or low phase angle measured by bio-impedance analysis.

Design

COPD patients (n = 103) evaluated in a subspecialty clinic between September 2024 and November 2025 completed SARC-F screening as part of routine care and underwent bio-impedance analysis for body composition assessment. Sarcopenia was defined by low skeletal muscle index (SMI) (<7.0 kg/m² in males and <5.5 kg/m² in females) (PMID: 30312372). Low phase angle, a marker of muscle function, was defined as < 5.0° in males and <4.6° in females (PMID: 34845859). SARC-F scores ≥4 were considered symptomatic. Diagnostic performance was assessed using area under the receiver operating characteristic curve (AUC).

Results

Participants were classified as NormalSMI (n = 51; age 69.6 ± 7.0 years) or LowSMI (n = 52; age 67.4 ± 8.7 years), with 58.3% female overall. Skeletal muscle mass and body mass index (BMI) differed significantly between groups (p < 0.001 for all), whereas SARC-F scores did not (p = 0.598). Weak correlations between SARC-F scores and skeletal muscle mass (R = −0.03) and phase angle (R = 0.04) were noted. SARC-F demonstrated poor discrimination for low SMI overall (AUC 0.49). However, among individuals with BMI <23, predictive performance modestly improved (AUC 0.61). When stratified by sex within this subgroup, SARC-F showed improved discrimination in males (AUC 0.71) but not females (AUC 0.49). Similarly, SARC-F demonstrated poor discrimination for low phase angle overall (AUC 0.45), which did not improve when BMI or sex-stratified. However, event rate for low phase angle was very high in the cohort (82%), which likely contributed to poor discrimination.

Conclusion

SARC-F scores show weak associations with both SMI and phase angle in COPD. However, SARC-F demonstrated improved diagnostic performance for LowSMI among males with BMI <23, suggesting that questionnaire-based sarcopenia screening may require sex- and body-composition-specific interpretation. These findings indicate that SARC-F should not be used as a standalone tool for sarcopenia detection in COPD.

This abstract is funded by: None