Better approach for autoimmune pulmonary alveolar proteinosis treatment: inhaled or subcutaneous granulocyte-macrophage colony-stimulating factor: a meta-analyses

Abstract Background Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare pulmonary disease caused by functional deficiency of granulocyte-macrophage colony-stimulating factor (GM-CSF). GM-CSF therapy in aPAP has been reported effective in some studies. This meta-analyses aimed to evaluate whether GM-CSF therapy, including inhaled and subcutaneous GM-CSF have therapeutic effect in aPAP patients. Methods We analyzed 10 studies searched from PubMed, EmBase, Web of Science, Wiley Online Library and Cochrane Collaboration databases to evaluate the pooled effects of GM-CSF treatment in aPAP patients. Results Ten observational studies involving 115 aPAP patients were included. The pooled analyses of response rate (81%, p < 0.001), relapse rate (22%, p = 0.009), PaO2 (13.76 mmHg, p < 0.001) and P(A-a)O2 (19.44 mmHg, p < 0.001) showed that GM-CSF treatment was effective on aPAP patients. Further analyses showed that inhaled GM-CSF treatment was more effective than subcutaneous GM-CSF therapy, including a higher response rate (89% vs. 71%, p = 0.023), more improvements in PaO2 (21.02 mmHg vs. 8.28 mmHg, p < 0.001) and P(A-a)O2 (19.63 mmHg vs. 9.15 mmHg, p < 0.001). Conclusions As two routes of exogenous GM-CSF treatment, inhaled and subcutaneous were both proven to have effect on aPAP patients. Furthermore, inhaled GM-CSF therapy showed a higher response rate, more improvements on PaO2 and P(A-a)O2 than subcutaneous GM-CSF treatment in aPAP patients, suggesting inhaled GM-CSF therapy could have more benefits on aPAP patients. Therefore, GM-CSF therapy, especially inhaled GM-CSF, might be a promising therapeutic option in treating aPAP