Sarcopenia: Defining the Diagnostic Landscape
Sarcopenia is a progressive loss of skeletal muscle mass and strength, significantly impacting quality of life and independence, especially in older adults. Defining what is the cut off point for sarcopenia is key for diagnosis, but there isn't a single universal threshold. Diagnostic criteria have evolved, with guidelines from groups like the European Working Group on Sarcopenia in Older People (EWGSOP) and its updated version, EWGSOP2, being widely used.
The EWGSOP2 Diagnostic Criteria (2018)
The EWGSOP2 guidelines prioritize low muscle strength as the primary indicator of probable sarcopenia. The diagnostic process is sequential:
- Probable Sarcopenia: Indicated by low muscle strength (grip strength < 27 kg for men, < 16 kg for women; chair stand test > 15 seconds for five rises).
- Confirmation of Sarcopenia: Low strength plus low muscle quantity or quality (ASM mass by DXA < 20 kg for men, < 15 kg for women; ASM/height² by DXA < 7.0 kg/m² for men, < 5.5 kg/m² for women).
- Severe Sarcopenia: Low muscle strength, low muscle mass, and low physical performance are all present.
The Role of Physical Performance in Diagnosis
Physical performance tests assess sarcopenia severity. Key cut-offs include a gait speed of ≤ 0.8 m/s, SPPB score ≤ 8, or TUG test ≥ 20 seconds.
Global Variations in Sarcopenia Cut-offs
Cut-off points vary across working groups due to differences in body size and demographics. The Asian Working Group for Sarcopenia (AWGS) and the FNIH Sarcopenia Project provide examples of regional and alternative criteria.
Measurement Techniques and Their Accuracy
The tools used to measure sarcopenia parameters vary. The table below compares common methods:
| Method | Primary Measure | Cost | Accuracy | Clinical Setting Suitability |
|---|---|---|---|---|
| Dual-energy X-ray Absorptiometry (DXA) | Appendicular Lean Mass (ALM) | Moderate to High | High | Good (Standard for routine assessment) |
| Bioelectrical Impedance Analysis (BIA) | Appendicular Skeletal Muscle Mass (ASM) | Low | Moderate (Affected by hydration) | Excellent (Portable, rapid) |
| Handgrip Dynamometry | Muscle Strength | Low | Good | Excellent (Simple, quick) |
| Gait Speed Test | Physical Performance | Low | Good | Excellent (Simple, predictive) |
| Computed Tomography (CT) & MRI | Muscle Mass/Quality | High | Very High (Gold Standard) | Limited (High cost, research focus) |
The Staging of Sarcopenia
Diagnosis allows for staging:
- Presarcopenia: Low muscle mass without reduced strength or performance.
- Sarcopenia: Low muscle mass plus either low strength or low performance.
- Severe Sarcopenia: Low muscle mass, low strength, and low performance.
Conclusion
There is no single cut off point for sarcopenia, but criteria from groups like EWGSOP2 are widely used. Diagnosis involves assessing muscle strength, mass, and physical performance. Regional differences exist. For more information, refer to {Link: NIH website https://pmc.ncbi.nlm.nih.gov/articles/PMC8658070/}.
