ORIGINAL ARTICLE   Open access

European Journal of Physical and Rehabilitation Medicine 2025 February;61(1):119-29

DOI: 10.23736/S1973-9087.24.08496-X

Copyright © 2024 THE AUTHORS

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lingua: Inglese

Association between muscle strength and echogenicity using greyscale ultrasound software: a diagnostic accuracy study in kidney transplant candidates

Carolina ACUÑA-PARDO ^{1, 2}, Elena MUÑOZ-REDONDO ^{1, 2}, Lou DELCROS-FORESTIER ^{1, 2}, Yulibeth G. CURBELO ¹, Carlos RODRÍGUEZ-HERNÁNDEZ ¹, Delky MEZA-VALDERRAMA ^{2, 3, 4}, Dolores SÁNCHEZ-RODRÍGUEZ ^{2, 5, 6}, Julio PASCUAL ^{7, 8}, Maria J. PÉREZ-SÁEZ ^{7, 9}, Ester MARCO ^{1, 2, 10} ✉

¹ Department of Physical Medicine and Rehabilitation, Hospital del Mar, Barcelona, Spain; ² Rehabilitation Research Group, Hospital del Mar Research Institute, Barcelona, Spain; ³ National Institute of Physical Medicine and Rehabilitation (INMFRE), Panama City, Panama; ⁴ Department of Physical Medicine and Rehabilitation, Caja de Seguro Social (CSS), Panama City, Panama; ⁵ Department of Geriatrics, Brugmann University Hospital, Université Libre de Bruxelles, Brussels, Belgium; ⁶ WHO Collaborating Center for Public Health Aspects of Musculo-Skeletal Health and Ageing, Division of Public Health, Epidemiology and Health Economics, University of Liège, Liège, Belgium; ⁷ Nephropathies Research Group, Hospital del Mar Research Institute, Barcelona, Spain; ⁸ Department of Nephrology, Hospital Universitario 12 de Octubre, Madrid, Spain; ⁹ Department of Nephrology, Hospital del Mar, Barcelona, Spain; ¹⁰ Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain

BACKGROUND: Advanced chronic kidney disease disrupts the delicate equilibrium between protein anabolism and catabolism, leading to alterations in muscle quantity, quality, and function. Musculoskeletal ultrasound emerges as a promising assessment tool due to its widespread availability and high reliability.
AIM: To evaluate the efficacy of rectus femoris (RF) echogenicity, measured using greyscale software, in identifying diminished muscle quality and strength in candidates for kidney transplant.
DESIGN: Post-hoc diagnostic accuracy study.
SETTING: Outpatients in a multimodal prehabilitation program pre kidney transplantation (KT).
POPULATION: Patients on the waiting list for KT.
METHODS: Sensitivity, specificity, likelihood ratios and area under the curve (AUC) for diagnostic efficacy of echogenicity (index test) assessed with the ImageJ software greyscale as a potential marker of quadriceps muscle weakness (reference test) were calculated. Muscle weakness was considered as maximal voluntary isometric contraction of the quadriceps (Q-MVIC) <40% of body weight. Other variables included body composition parameters derived from multifrequency electrical bioimpedance, upper limb muscle strength (handgrip), and RF thickness assessed by ultrasound. Statistical tests: Chi-square, t-Student, Pearson correlation coefficients (r), bivariate and multivariate logistic regression models. Statistical significance level ≤0.05.
RESULTS: Of 112 patients (mean age: 63.6, 76% male), 72 (63.7%) exhibited quadriceps weakness, while 80 (70.8%) had some degree of overhydration (extracellular water/total body water ratio >0.390). The echogenicity cut-off point of highest concordance with muscle weakness was 70, boasting a sensitivity of 83%, specificity of 57%, and AUC of 0.671 (CI 95% 0.570-0.772 [P=0.003]). Echogenicity >70 was associated with a 3.4-fold higher risk of muscle weakness (crude OR = 3.4 [CI95% 1.4 to 8.0]), which persisted after adjusting for age, height, weight and RF thickness.
CONCLUSIONS: The RF echogenicity exhibits fair validity in identifying muscle weakness among candidates for KT. However, it cannot be endorsed as a standalone diagnostic tool in this population.
CLINICAL REHABILITATION IMPACT: Early identification of muscle weakness would advance efforts to mitigate morbidity and mortality through targeted measures.

KEY WORDS: Muscles; Ultrasonography; Muscle strength; Kidney transplantation