Defining and diagnosing sarcopenia

Sarcopenia is a growing health problem, particularly in countries with disproportionately aging populations. Sarcopenia is of course also possible in younger persons too, albeit less commonly. It's identified by several criteria, taking into account low muscle strength, quality, and physical performance. In recent years, muscle strength has come to the forefront as a better indicator than mass in predicting adverse outcomes.

Muscle strength
Source: Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing, 2019 Jan 1;48(1): 16-31

For most people, muscle mass develops during early life, reaching a peak in both mass and strength in the 20s and 30s, after which both tend to decrease with age.
 
There are currently two major groups whose standards and diagnostic protocols are commonly adopted for sarcopenia - the European Working Group on Sarcopenia in Older People (EWGSOP), and the Asian Working Group for Sarcopenia. (AWGS). The purpose of such protocols and testing procedures is to allow for early identification of people at risk for sarcopenia and enable timely intervention.
 
Overall, both diagnostic protocols are largely similar, beginning with basic tests or questionnaires to help identify people that may potentially be at risk for sarcopenia, with more advanced tests to follow if there are warning signs.
 
Strength, Assistance with walking, Rising from a chair, Climbing stairs, and Falls (SARC-F) and Calf Circumference (SARC-CalF) questionnaire
  Question Score
Strength How much difficulty do you have in lifting and carrying 10 pounds?
None: 0
Some: 1
A lot or unable: 2
Assistance in walking Assistance in walking: How much difficulty do you have walking across a room?
None: 0
Some: 1
A lot, use aids, or unable: 2
Rise from a chair How much difficulty do you have transferring from a chair or bed?
None: 0
Some: 1
A lot or unable without help: 2
Climb stairs How much difficulty do you have climbing a flight of 10 stairs?
None: 0
Some: 1
A lot or unable: 2
Falls How many times have you fallen in the past year?
None: 0
less than 3 falls: 1
4 or more falls: 2
Calf circumference Measure patient's exposed right calf circumference with legs relaxed and feet 20 cm apart from each other
Male:
> 34 cm: 0; ≦ 34 cm: 10
Female:
> 33 cm: 0; ≦ 33 cm: 10

 
If preliminary screening results indicate subject may be at risk, further tests for muscle strength, muscle quality, and physical performance are recommended, detailed below. Note that different cutoff definitions are used between Europe and Asia, taking into account anthropometric and cultural or lifestyle-related differences at a population level.

Cutoff definitions
  EWGSOP AWGS
  Questionnaire / Anthropometric measurement
Preliminary Screening SARC-F
SARC-F ≧ 4
Or
SARC-CalF ≧ 11
or
Calf circumference (M: < 34 cm; F: < 33 cm)
  Low muscle strength
Grip strength
Male < 27 kg
Female < 16 kg
Male < 28 kg
Female < 18 kg
Chair stand 5 repetitions in > 15s 5 repetitions in ≧ 12s
  Low muscle quality
Appendicular Skeletal Muscle Index (ASM/height2)
Male < 7.0 kg/m2
Female < 5.5 kg/m2
Male < 7.0 kg/m2
Female < 5.7 kg/m2
  Low physical performance
Gait speed < 0.8 meters/s (4 meters) < 1.0 meters/s (6 meters)
Short Physical Performance Battery (SPPB) ≦ 8 points ≦ 9 points
Timed-up-and-go-test (TUG) ≧ 20 seconds  
400 meter walk Unable to complete or ≧ 6 minutes  
Sources:
Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing, 2019 Jan 1;48(1): 16-31
Asian Working Group for Sarcopenia: 2019 Consensus Update on Sarcopenia Diagnosis and Treatment. JAMDA 21 (2020) 300-307
 
Updated versions of sarcopenia typically categorize subjects into different levels.
  Muscle strength Muscle mass Physical performance
No sarcopenia Normal Normal Normal
Probable sarcopenia Low Normal Normal
Sarcopenia Low Low Normal
Severe sarcopenia Low Low Low

Find-Assess-Confirm-Severity
To summarize the recommended method of detecting and diagnosing sarcopenia, the process is effectively to identify, assess, and confirm.
 
Sarcopenia Assessment Flowchart
 
 
As can be seen in the assessment and diagnosis algorithms recommended, handgrip and muscle measurements are key methods used, in addition to circumference and physical sitting/standing/walking tests.
 
Utilizing certified and professionally calibrated grip strength dynamometers like the Charder MG4800 help ensure that measurement results are accurate. For increased convenience, models with automatic wireless transmission help save time and reduce error rate, streamlining the measurement process.
 
Similarly, the muscle quantity/quality assessment can be done using BIA Body Composition Analyzers like the Charder MA601 and MA801. As muscle assessments can vary significantly between different brands, it is important to choose a certified device with sufficient research and validation backing, and also make sure you follow the recommended BIA measurement protocol, such as measuring at a consistent time of day on an empty stomach.

Recommended reading

Top