Objective To systematic investigate whether phase angle of bioelectrical impedance is associated with the functionality, severity, and prognosis of individuals afflicted with chronic obstructive pulmonary disease (COPD). Methods Relevant literature from the PubMed, Embase, Web of Science, Scopus, CNKI, and WanFang databases was retrieved, and literature screening and data extraction in accordance with standardized methods were conducted. Literature quality was assessed by utilizing Mixed Methods Appraisal Tool. Subsequently, data pertaining to the results was extracted for summarization and induction, and descriptive analyzed through qualitative synthesis. Results A total of 11 studies, encompassing 2189 subjects, were included in this review, and the overall quality of the literature was deemed relatively high. Of these studies, three examined the correlation between phase angle and the severity of COPD, eight studies examined the correlation between phase angle and pulmonary and physical function in COPD, and seven studies reported the association between phase angle and adverse outcomes such as hospitalization time, nutritional risk, acute exacerbation and mortality in COPD. The collective findings suggestted that reduced levels of phase angle are linked to severe illness, diminished function, and unfavorable prognosis among individuals with COPD. Phase angle emerged as an independent predictor of lung function, physical exercise endurance, acute exacerbation and mortality in COPD patients. Conclusion The phase angle level of COPD patients is associated with their disease severity, function, and prognosis, and is an potential available indicator for clinical management of COPD patients.
Objective To investigate the correlation between granulocyte-macrophage colony-stimulating factor (GM-CSF) antibody levels and disease severity in autoimmune pulmonary alveolar proteinosis (PAP). Methods A retrospective analysis was conducted on 18 patients with autoimmune PAP. Serum GM-CSF antibody levels were measured, and pulmonary function [diffusion capacity of the lung for carbon monoxide as a percentage of predicted value (DLCO%pred) and forced vital capacity as a percentage of predicted value(FVC%pred)], oxygenation index, high-resolution CT imaging scores (percentage of ground-glass opacification/consolidation in each lobe and proportion of Hounsfield unit partitions) were evaluated. Spearman correlation analysis and comparison between high- and low-antibody groups were performed. Results A total of 18 patients were enrolled, with GM-CSF antibody levels ranging from 66.2 to 445 U/mL. Correlation analysis showed that GM-CSF antibody levels were not significantly correlated with DLCO%pred, FVC%pred, oxygenation index, disease severity score, or the percentage of whole-lung ground-glass opacification/consolidation. No statistically significant differences were observed in any severity indicators between the high-antibody group (>400 U/mL) and the moderate-to-low antibody group (≤400 U/mL) (P>0.05). Conclusions Although GM-CSF antibody level is a key diagnostic marker for autoimmune PAP, it cannot serve as a reliable biomarker for assessing disease severity. In clinical practice, judging disease severity based on antibody titer should be avoided.