Association between SARC-F as a self-report screening tool for sarcopenia and muscle strength, physical performance, daily activity, patient-reported outcomes and body composition in patients with spondyloarthritis.

A notable proportion of SpA patients had a SARC-F score indicating higher sarcopenia risk, but DXA-confirmed sarcopenia was rare.

• Overall 54 of 213 patients with SpA had a SARC-F score ≥4 (24.4%)
• The cohort comprised 65.7% axSpA and 34.3% PsA patients
• DXA identified sarcopenia in only 4 patients and sarcopenic obesity in 4 patients (7.7% each among those with SARC-F ≥4)

Patients with SARC-F scores ≥4 had worse clinical and functional profiles compared to those with scores <4.

• Patients with SARC-F ≥4 were older, predominantly female or obese, and had longer disease duration
• These patients had higher disease activity, lower physical performance, decreased muscle strength, and lower daily activity
• They also had more unfavourable body composition on DXA assessment

Total SARC-F score was consistently associated with muscle strength, physical performance, patient-reported outcomes, and DXA body composition components.

• Linear regression was used to examine associations, adjusted for age and sex
• Associations were found across multiple domains including muscle strength, physical performance, PROs, and DXA components
• Higher body mass index and patient global assessment were independently associated with higher SARC-F scores

The SARC-F ≥4 threshold demonstrated moderate specificity but low sensitivity for identifying DXA-defined sarcopenia, with a high negative predictive value.

• Specificity for DXA-defined sarcopenia was 76%
• Sensitivity for DXA-defined sarcopenia was 50%
• Negative predictive value was 97%
• This suggests SARC-F is better at ruling out sarcopenia than confirming it in this population

The study used a cross-sectional design with DXA-based body composition assessment in a mixed SpA population.

• Total sample size was 213 patients with SpA
• Body composition was assessed by dual-energy X-ray absorptiometry (DXA)
• Variables were compared between patients with SARC-F score ≥4 and <4
• The study included both axial spondyloarthritis (65.7%) and psoriatic arthritis (34.3%) patients

Further research is needed to clarify SARC-F's clinical utility for risk stratification in rheumatic diseases.

• SARC-F showed limited ability to identify DXA-defined sarcopenia despite associations with disease activity and physical function
• The authors note that SARC-F's role in risk stratification for rheumatic disease populations requires further investigation
• The high negative predictive value (97%) suggests potential utility as a screening tool to exclude sarcopenia