Respiratory medicine
October 20, 2026 · via Europe PMC
Foot-to-foot lower-limb phase angle as a predictor of reduced exercise capacity in patients with interstitial lung disease: A comparative study with muscle mass and pulmonary function.
Kaneko K, Ishizaka M, Hara T, +7 more, Izumo T.
AI summary — for doctors, generated from the abstract only
Foot-to-foot lower-limb phase angle predicted reduced exercise capacity in interstitial lung disease better than muscle mass or lung function measures.
What was studied
Retrospective study of 68 ILD patients comparing bioelectrical impedance phase angle with CT erector spinae muscle area and pulmonary function for predicting reduced 6-minute walk distance, with bootstrap internal validation.
Key findings
- Phase angle was independently associated with reduced exercise capacity (OR about 0.21-0.23 in the two models).
- Its AUC (0.802) exceeded %DLCO (0.729) and muscle area (0.701).
- Combining age, %DLCO and phase angle reached an AUC of 0.833.
Clinical relevance
A simple, non-invasive bedside measure may flag early functional decline in ILD that spirometry and DLCO miss.
Who should care
Limitations
Small, retrospective, single-cohort sample with only internal validation, and the abstract is partly cut off on how reduced capacity was defined.
Consider phase angle as a screening adjunct for exercise limitation in ILD, pending external validation.
This is an AI-generated summary of the published abstract, not a clinical recommendation. It may not reflect the full text or subsequent updates — verify against the original source before acting on it.
Abstract
Background
Reduced exercise capacity, measured by the 6-min walk distance (6MWD), is a critical prognostic factor in interstitial lung disease (ILD). However, conventional physiological markers often fail to identify early functional decline. We aimed to evaluate whether the foot-to-foot lower-limb phase angle (F-F PhA), a non-invasive surrogate marker of muscle quality, predicts reduced exercise capacity better than traditional muscle mass and pulmonary function indices.
Methods
In this retrospective study of 68 patients with ILD, F-F PhA was measured using bioelectrical impedance analysis, and erector spinae muscle area (ESM_CSA) via computed tomography. Reduced exercise capacity was defined as 6MWD CO or %FVC), with internal validation performed via 1000-resample bootstrapping.
Results
In multivariable analysis, F-F PhA was independently associated with a 6MWD CO (OR: 0.228, 95% CI: 0.088-0.591, p = 0.002; bootstrap p = 0.005) or %FVC (OR: 0.213, 95% CI: 0.091-0.496, p = 0.001; bootstrap p = 0.001). ROC analysis showed F-F PhA had the highest discriminative accuracy (AUC: 0.802), outperforming %DLCO (AUC: 0.729) and ESM_CSA (AUC: 0.701). Combining age, %DLCO, and F-F PhA achieved the highest performance (AUC: 0.833).
Conclusions
F-F PhA serves as a robust, independent indicator for predicting reduced exercise capacity in ILD, outperforming conventional muscle mass. As a non-invasive tool, F-F PhA complements established functional tests in screening for early physical decline.
DOI
10.1016/j.rmed.2026.109236
PMID
42901131
Research metadata (titles, abstracts, authors, publication dates) is sourced from Europe PMC, which aggregates content from PubMed/MEDLINE, PubMed Central, and other providers under the U.S. National Library of Medicine (NLM/NCBI). NLM does not claim copyright on abstracts; the original journal publishers or authors may hold rights to the full articles. AI-generated summaries are derived only from the abstract, never the full text, and are always labeled as AI-generated.
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