Diagnostic uncertainty in respiratory sarcopenia: accuracy of available tests and clinical implications: a systematic review and meta-analysis

Purpose Respiratory sarcopenia (RS) is an emerging clinical condition associated with pneumonia and mortality, but its diagnosis remains uncertain because standardized criteria are lacking. This systematic review and meta-analysis evaluated the diagnostic accuracy of peak expiratory flow rate (PEFR), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP) for identifying RS in older adults. Methods Eight databases were systematically searched for studies involving adults aged ≥60 years. Risk of bias was assessed using QUADAS-2. Test-specific and overall pooled sensitivity and specificity were calculated for PEFR, MIP, and MEP according to the operational definitions adopted by the primary studies. Results Seven studies comprising 2,466 participants were included (mean age range, 70.2–80.6 years). Overall pooled sensitivity was 0.614 (95% CI 0.453–0.753) and specificity was 0.726 (95% CI 0.443–0.898), with substantial heterogeneity (bivariate I 2 =0.929). Test-specific analyses showed distinct profiles: MEP-based approaches had relatively higher sensitivity and lower heterogeneity, MIP-based approaches had comparatively higher specificity, and PEFR-based approaches showed lower and more variable diagnostic performance. Meta-regression found no statistically detectable differences by sex or sarcopenia diagnostic criteria; however, these analyses were exploratory and underpowered. Conclusion Respiratory muscle-related measures show variable diagnostic performance for identifying RS. Current evidence is insufficient to establish the superiority of any single test or recommend a clinical reference standard. Prospective multicenter studies using standardized criteria and diverse populations, together with international consensus on RS definition, are needed to support future clinical recommendations. Registration Number PROSPERO—CRD42023494910.