Sarcopenia Assessment in Resource-Constrained Settings: Expert Agreement on Surrogate Measures

Purpose

Sarcopenia, the progressive loss of muscle mass and function with age, is diagnosed by assessing muscle strength, physical performance, and muscle mass. However, the tools required are often costly, inaccessible, or unsuitable for use in low-resource or remote settings. This study aimed to identify practical surrogate measures that are conceptually aligned with established sarcopenia diagnostic criteria and can be integrated into digital health platforms to enable remote screening and monitoring using an expert agreement process.

Methods

A narrative literature review was conducted to identify proxy measures for muscle strength (HGS), physical performance, and muscle mass. This was followed by two rounds of expert agreement. The Content Validity Index (CVI), defined as the number of experts in agreement divided by the total number of experts for each pragmatic proxy, was calculated after each round to assess the relevance and appropriateness of each measure. A pragmatic proxy with a CVI of 0.7 or higher was included.

Results

Eight proxies for HGS were identified across ten studies, with the five-times sit-to-stand test (5STS) being the most common. The 5STS has a higher agreement and was considered a relevant and appropriate surrogate by the expert panel for both muscle strength (CVI = 0.8 for both relevance and appropriateness) and physical performance (CVI = 1 for relevance and 0.8 for appropriateness), whereas the TUG could be a promising measure for physical performance (CVI = 1 for both relevance and appropriateness). Calf circumference (CC) offers a low-cost alternative for assessing muscle mass (CVI = 1 for relevance and 0.7 for appropriateness).

Conclusion

The 5STS, TUG, and CC were identified as relevant and appropriate pragmatic proxy measures for assessing sarcopenia, with potential for integration into digital screening tools in low-resource settings. Further clinical studies are required to establish their validity, reliability, and feasibility for remote assessment.

Author Summary

Sarcopenia is an age-related condition involving the loss of muscle strength, physical ability, and muscle mass. Identifying it usually requires specialised equipment and face-to-face assessment, which may not be available in remote or resource-limited settings. We therefore aimed to identify simple, practical measures that could support sarcopenia screening through digital health platforms.

We reviewed the existing literature to identify possible alternatives to conventional assessments of muscle strength, physical performance, and muscle mass. We then asked a panel of experts to evaluate these measures through a two-round agreement process based on their relevance and suitability. The experts identified the five-times sit-to-stand test, which measures how quickly a person can rise from a chair five times, as a practical indicator of muscle strength and physical performance. The Timed Up-and-Go test was considered a promising measure of physical performance, while calf circumference was identified as a simple, low-cost indicator of muscle mass.

Together, these measures could make sarcopenia screening more accessible and suitable for digital use in low-resource settings. Further clinical research is needed to determine whether they provide accurate, reliable, and feasible assessments when used remotely.