Fig. 4

Forrest plot of the result of univariate analysis for age at the onset of acute exacerbation as a prognostic factor. The result of univariate analysis in three studies was pooled for meta-analysis. There was no significant difference in age at the onset of acute exacerbation (AE) between decedents and survivors of AE of systemic autoimmune disease-associated interstitial lung disease (ILD) with a mean difference (MD) of 0.41 (95% confidence interval: − 8.74 to 9.57, p = 0.93). There was no heterogeneity (chi² = 0.17, p = 0.92, I² = 0%)