Pleural effusion as a predictor of rapidly progressive interstitial lung disease and mortality in idiopathic inflammatory myopathies.

OBJECTIVES

This study aimed to evaluate the clinical significance of pleural effusion in adult patients with idiopathic inflammatory myopathies (IIM).

METHODS

We assessed a cohort of 158 consecutive patients with IIM. Clinical features and survival rates were compared between patients with and without pleural effusion.

RESULTS

Of those 158 IIM patients, 28 (17.7%) developed pleural effusion. 125 (79.1%) IIM patients had interstitial lung disease (ILD), 26 (20.8%) of which developed pleural effusion. Notably, pleural effusion was associated with a higher incidence of lower lung zone consolidation, rapidly progressive ILD (RP-ILD) and elevated high-resolution computed tomography (HRCT) score, and could robustly predict RP-ILD independently [HR 7.863 (2.160-28.617), p=0.002] in IIM-ILD patients. IIM patients with pleural effusion presented with increased systemic inflammatory response, including more fever, elevated white blood cell count, neutrophil/lymphocyte ratio, C-reactive protein, and erythrocyte sedimentation rate, alongside reduced lymphocyte percentage. Pleural effusion was also associated with more ILD, lower lung zone consolidation, pericardial effusion and RP-ILD, higher HRCT score, and lower HB and albumin levels in IIM. Except for neutrophil/lymphocyte ratio, ILD and pericardial effusion, other correlative variables were potential predictors of higher mortality in IIM. Furthermore, pleural effusion remained an independent predictor of higher mortality in IIM [HR 5.05 (1.633-15.62), p=0.005].

CONCLUSIONS

Pleural effusion showed a significant positive association with severe phenotypes of ILD and was the powerful predictor of RP-ILD in IIM-ILD. Furthermore, pleural effusion could reveal adverse disease phenotypes with higher systemic inflammatory level and predict higher mortality independently in IIM.