The role of ultrasound of the quadriceps femoris in people with cystic fibrosis: a systematic review and meta-analysis.

OBJECTIVE

To conduct a systematic review and meta-analysis of the evidence on the use of ultrasound to assess quadriceps morphology in people with cystic fibrosis (PwCF), focusing on muscle thickness, cross-sectional area, and associations with clinical outcomes.

METHODS

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered on the International Prospective Register of Systematic Reviews platform (ID: CRD42024590549). The PubMed, Embase, Scopus, Web of Science, SciELO, and Cumulative Index to Nursing and Allied Health Literature databases were comprehensively searched without time restrictions. Gray literature and manual reference screening were also included. Observational studies assessing quadriceps morphology via ultrasound in people with CF and reporting quantitative outcomes were eligible. Two reviewers independently conducted study selection, data extraction, and risk of bias assessment using the Joanna Briggs Institute tool. Meta-analysis was performed with Cochrane's Review Manager software.

RESULTS

Five studies met the inclusion criteria. People with CF showed reduced quadriceps thickness and cross-sectional area, particularly those who were malnourished. Moderate correlations were observed between ultrasound measurements and clinical parameters such as pulmonary function, fat-free mass index, and muscle strength. Meta-analysis revealed a significant reduction in rectus femoris muscle thickness in people with CF when compared with controls (mean difference: -0.50 cm; 95% CI, -0.78 to -0.22; p = 0.0004), with high heterogeneity (I2 = 94%). Risk of bias was moderate because of small sample sizes and methodological variability.

CONCLUSIONS

Although the evidence is limited and heterogeneous, people with CF appear to show reduced quadriceps morphology, with associations with nutritional and functional status. Further high-quality studies are needed to confirm our findings and determine the clinical utility of ultrasound in this population.