Objectives: Anti-nuclear matrix protein 2 (NXP2) antibody is a rare myositis-specific antibody. Thus, the pattern and prognosis of interstitial lung disease (ILD) in NXP2-positive patients remain unclear. This study investigates the clinical features and effects of pulmonary complications on survival in NXP2-positive patients.
Methods: We retrospectively analysed the clinical and follow-up data of a cohort of 33 hospitalised adult patients with anti-NXP2 antibody positivity at three tertiary rheumatology centres from June 2017 to December 2020.
Results: Thirty-three patients were enrolled, and 87.9% (29/33) had dermatomyositis. The major pulmonary lesions manifested as various types of ILD (14/33, 42.4%), bilateral pleural effusion (2/33, 6.1%) and diffuse alveolar haemorrhage (1/33, 3%). Only 3 patients (3/33, 9.1%) had respiratory symptoms at onset. The most common lung imaging manifestations were non-specific interstitial pneumonia (NSIP) and/or organising pneumonia (OP) (11/14, 78.6%). Patients in the ILD group were older than those in the non-ILD group (p=0.002). Logistic regression analysis showed that age (p=0.008) was the only independent predictor for ILD. Kaplan-Meier survival curves displayed no association between ILD and all-cause death (log-rank p=0.84). None of the deaths during follow-up were directly related to ILD.
Conclusions: Adult patients with anti-NXP2 antibody positivity mainly had dermatomyositis. Concurrent ILD is not uncommon, but clinical manifestations are often latent. NSIP and/or OP are the most common patterns. ILD is more common in older age groups. Although the prognosis of patients in the ILD group is not very poor, early screening may help to improve prognosis and quality of life.