Clinical Characteristics and Outcomes of Patients with Anti-MDA5 Antibody Associated Rapidly Progressive Interstitial Lung Disease (RP-ILD): A Case Series.

Objective: To describe the clinical profile and treatment outcomes of a longitudinal series of patients with rapidly progressive interstitial lung disease (RP-ILD) associated with anti MDA 5 antibody.

Methods: RP-ILD patients were identified from a prospective cohort of adult patients with idiopathic inflammatory myopathy (IIM). Clinical, demographic, and serological parameters of all patients were recorded using a structured proforma. Rapidly progressive ILD was defined as the development of radiological deterioration and hypoxemia within 3 months of the onset of respiratory symptoms. The diagnosis of RP-ILD was made after high-resolution CT chest and multidisciplinary discussion. RPILD patients were followed up with serial pulmonary function tests (PFT) every 3 months and echocardiography every 6 months.

Results: Among 58 patients with IIM, five patients (3 female, 2 male) had RP-ILD. All the five patients had amyopathic presentation with polyarthritis, negative anti-nuclear antibody (ANA) and strong positivity (3+) for anti MDA 5 antibody by line immunoblot assay. The patients were treated with various combinations of immunosuppressants/immunomodulators. Two patients expired, one had stabilisation of lung function and the other two patients showed improvement of lung function over a median follow up of 24 months. High levels of serum ferritin and LDH were seen in non-survivors.

Conclusion: A clinically amyopathic presentation with polyarthritis, negative ANA and a favourable long-term response to combination immunosuppressive therapy defined the clinico-serological profile and treatment response of our anti MDA5 positive RP-ILD patients.