Abstract Rationale Subspecialty interstitial lung disease (ILD) clinics provide coordinated, multidisciplinary care that improves diagnostic accuracy and outcomes. Yet, even within a single health system, many patients with ILD receive care in non-specialty settings due to geographic, socioeconomic, and referral barriers. The characteristics of patients seen in non-subspecialty care pathways and the impact of care setting on diagnosis, management, and outcomes remain poorly defined. Methods We conducted a retrospective cohort study of adults with ILD seen at an academic medical center with ILD expertise between 2013-2024 using a de-identified clinical data warehouse integrating structured and unstructured electronic health record data and state death records. Patients with ILD were identified using an institutional ILD database and a validated ILD machine-learning classification algorithm, then stratified by care setting: ILD subspecialty clinic vs. other ambulatory settings. Primary outcomes included diagnostic testing, medication use, healthcare utilization, and survival. Multivariable regression and Cox proportional hazards models were adjusted for age, sex, race/ethnicity, ILD subtype, comorbidity, and socioeconomic status. Results Among 6,637 patients with ILD, two-thirds were seen in the ILD clinic and one-third in non-specialty settings. Patients in non-specialty pathways were more likely to be younger, identify as Black or Latinx, reside in lower-socioeconomic areas, and have nonspecific ILD diagnoses (p 0.001 for all). In adjusted analysis, ILD-clinic patients had higher odds of undergoing CT chest (OR 3.32, 95% CI 2.84-3.88, p 0.01) and lower odds of lung biopsy (OR 0.52, 95% CI 0.45-0.59, p 0.01) as part of diagnostic evaluation, as well as a higher odds of treatment with an antifibrotic (OR 2.85, CI 2.31-3.51, p 0.001) and lower odds of treatment with chronic prednisone (OR 0.72, CI 0.66-0.82, p = 0.04). Additionally, ILD-clinic patients had a longer time from diagnosis to first emergency room visit or hospitalization and significantly lower hazard of death compared to those seen in other ambulatory settings (HR 0.57, 95% CI 0.45 to 0.72, p 0.001). Conclusions Within a single academic health system, ILD patients managed in a subspecialty clinic received more guideline-concordant diagnostics and therapy, reduced healthcare utilization, and significantly improved survival compared to those managed in non-specialty settings. Patients in non-specialty settings were disproportionately from racially and ethnically minoritized and socioeconomically disadvantaged groups. This study highlights the implications of inequitable access issues within institutions offering sub-specialty ILD care. Health systems can address this gap with streamlined referral pathways, interventions to mitigate structural access barriers, and scalable strategies to expand ILD expertise. This abstract is funded by: Boehringer Ingelheim
Farrand et al. (Fri,) studied this question.