The clinical features and mortality predictors for idiopathic inflammatory myopathies: a retrospective study of 572 patients and the "AIRMT" Score.

INTRODUCTION/OBJECTIVES: Idiopathic inflammatory myopathies (IIM) accompanied with interstitial lung disease (ILD) are often rapidly progressive and associated with poor prognosis. This study aims to explore the different clinical characteristics and prognostic factors for IIM with and without ILD and to develop a simple predictive model.

METHODS

We retrospectively evaluated 572 consecutive patients with IIM from January 2017 to May 2022. Clinical characteristics, comorbidities, survival outcomes, and treatments were assessed. The predictors of all-cause mortality were investigated by Cox regression analysis. An ROC curve was drawn to evaluate the predictive value of independent risk factors.

RESULTS

Patients with IIM-ILD were older and exhibited more respiratory and arthritis symptoms, but fewer tumor comorbidities. The first-year survival rate was 86% for ILD and 95% for non-ILD. The mortality rate in IIM-ILD patients was higher than in non-ILD patients (15.9% vs 6.2%, P = 0.001). ILD patients were more susceptible to various types of infections (bacteria, Pneumocystis jirovecii pneumonia (PJP), fungi, cytomegalovirus, all P < 0.001) and had a higher incidence of intubation (5.1% vs 1.2%, P = 0.009). Age, respiratory failure (RF), tumor, and MDA5 antibodies were independent predictors of survival for both IIM and IIM-ILD. Then, we established the "AIRMT" score and simple "AIRMT" score, which demonstrated good predictive capabilities with an AUC of 0.816 (95% CI 0.766-0.866) and 0.791 (95% CI 0.737-0.846).

CONCLUSIONS

IIM-ILD patients have higher mortality rates and are more susceptible to infections than non-ILD. This study identified various clinical features and several risk factors associated with all-cause mortality in IIM. The "AIRMT" score was constructed as a reliable survival predictor, offering valuable guidance for further research. Key Points • Patients with IIM-ILD were older and exhibited more respiratory and arthritis symptoms but had fewer tumor comorbidities. • IIM-ILDs have higher all-cause mortality rates and are more prone to infections compared to non-ILD cases. • Age, respiratory failure, tumor comorbidity, and MDA5 antibodies are identified as independent predictors of survival for both IIM and IIM-ILD patients. • We developed a practical clinical model, the "AIRMT" score, which could be a reliable and easy-to-evaluate clinical tool to predict all-cause mortality.