Accuracy of Ultrasound Measurements of Muscle Thickness in Identifying Older Patients With Sarcopenia and Its Impact on Frailty: A Systematic Review and Meta-Analysis.

Objectives: The aim of this systematic review was to assess the diagnostic test accuracy of muscle ultrasound for identifying older patients with sarcopenia and to investigate its association with frailty.

Design: Systematic review and meta-analysis of observational studies. Comprehensive searches were conducted in PubMed, MEDLINE, Cochrane Library, Scopus, and Embase through October 2024.

Setting and participants: Clinical and community settings across 7 countries, with 2537 adults aged ≥65 years.

Methods: Two reviewers assessed study quality using QUADAS-2. Data on participant characteristics, ultrasound methods, and diagnostic outcomes were extracted. Pooled sensitivity, specificity, diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) curve were calculated with a random-effects model. Sensitivity analyses ensured robustness.

Results: Pooled sensitivity was 0.85 (95% CI, 0.78-0.93), specificity was 0.74 (95% CI, 0.65-0.81), DOR was 16.65 (95% CI, 4.90-96.67), and SROC-area under the curve was 0.87, indicating moderate to high diagnostic accuracy. Association with frailty yielded an odds ratio of 7.91 (95% CI, 6.15-10.17). Most studies received an "unclear" rating in several QUADAS-2 domains, especially in patient selection and reference standards, indicating limitations in study design that may impact the generalizability of results.

Conclusions and implications: Ultrasound is a reliable, noninvasive, and cost-effective tool for diagnosing sarcopenia in older patients. Further research should standardize cutoffs and explore integration with other methods.