High Ferritin Predicts Mortality in Patients With Interstitial Pneumonia and an Underlying Autoimmune Disease

To identify early predictive markers in patients with chronic interstitial pneumonia (IP) associated with an underlying autoimmune disease (AIP), aiming to facilitate personalized follow-up and treatment.

We assessed the predictive value of process and host factors on mortality in a cohort of 124 patients (86 women) with autoimmune interstitial pneumonia (AIP). This cohort comprised 66 cases of connective tissue disease-associated interstitial pneumonia (CTD-IP), 40 patients with interstitial pneumonia with autoimmune features (IPAF), and 18 patients with undifferentiated autoimmune IP. All patients had a minimum follow-up of 2 years or a fatal outcome. We included demographics, clinical diagnostic subgroups, specific antibodies, morphological patterns, and relevant laboratory tests in our analysis. For the bivariate analysis, we employed Student's t-test, Fisher's exact test, and survival techniques. Prediction models for death risk were developed using logistic regression.

During the follow-up period, there were 29 deaths, resulting in an incidence rate of 3.09 per 100 patient-year. Factors associated with an increased risk of death included older age at diagnosis, cardio-respiratory comorbidities, and a simultaneous onset of intersticial pneumonia and systemic manifestations. In contrast, clinical diagnosis and radiographic patterns did not show a significant association with mortality risk. Additionally, elevated levels of lactate dehydrogenase, sedimentation rate, C-reactive protein, and ferritin were significantly linked to fatal outcomes. Among these, ferritin emerged as the most potent predictor in the multivariate model, with an odds ratio of 5.9 (p = 0.002).

Our data emphasize the importance of monitoring inflammatory markers, particularly ferritin levels, to assess prognosis across various subtypes of autoimmune intersticial pneumonia.