Treatment trajectories by radiologic pattern of lung injury in interstitial lung disease with myositis-associated antibodies: a retrospective cohort study

Abstract Objectives Lung involvement in interstitial lung disease (ILD) with myositis-associated antibodies (myositis-ILD) predominantly has two radiologic patterns—nonspecific interstitial pneumonia (NSIP) and organizing pneumonia (OP)—that often coexist, yet clinical outcomes of these patterns remain unclear. We aimed to describe functional and radiologic trajectories during immunomodulatory therapy by predominant radiologic pattern in myositis-ILD. Methods In this retrospective, single-center cohort study, we studied participants from the Northwestern University ILD Registry with a circulating myositis-associated antibody, ILD, and at least 6 months of immunomodulatory therapy during a 24-month observation period. Two thoracic radiologists assigned the predominant radiologic pattern (NSIP or OP). The primary outcome was change in forced vital capacity (FVC); secondary outcomes were change in diffusing capacity (DLCO) and qualitative and quantitative (Kazerooni score) radiologic change. Groups were compared with Fisher exact and Wilcoxon rank-sum tests. Results Forty-one participants were characterized (29 [71%] OP-predominant, 12 [29%] NSIP-predominant). Both subgroups had improved FVC on immunomodulatory therapy (OP + 0.36 L [p = 0.006]; NSIP +0.25 L [p = 0.09]). DLCO did not change significantly in either subgroup (OP + 1.22 [p = 0.11]; NSIP -0.75 [p = 0.37]). The OP cohort improved on qualitative imaging analysis (p < 0.05), driven by reduced groundglass/consolidative opacity (p = 0.006). Participants with NSIP/OP overlap had greater baseline radiologic severity. Conclusions In myositis-ILD, both radiologic subgroups showed measurable functional and radiologic change during immunomodulatory therapy, with larger improvements in the OP-predominant subgroup; the magnitude of change did not differ significantly between subgroups. These descriptive, hypothesis-generating findings require multicenter validation.