Sex- and Race-Based Differences in the Treatment of Interstitial Lung Diseases in North America and Australasia

Background: Biological sex, gender, and race are important considerations in patients with interstitial lung diseases (ILDs).

Research question: Does a patient's sex assigned at birth, and race, influence ILD treatment initiation?

Study design and methods: Patients with ILD from three longitudinal prospective registries were compared in this observational study. ILD-related medications included antifibrotics and immunomodulating medications. Race was dichotomized as "White" vs "non-White." Time to treatment initiation was determined from the date of the initial ILD registry visit to the date of first medication initiation. Proportions of treated patients were compared between groups by χ² test. Cox proportional analysis was used to determine how sex and race were associated with time to treatment initiation stratified by ILD diagnosis.

Results: A total of 4,572 patients were included across all cohorts. The proportion of men who received treatment was higher than for women in the Canadian cohort (47% vs 40%; P < .001), and the proportion of White patients who received treatment was also higher compared with non-White patients (46% vs 36%; P < .001). In contrast, the proportion of treated men in the Chicago cohort was lower compared with women (56% vs 64%; P = .005), and that of White patients was lower compared with non-White patients (56% vs 69%; P < .001). No sex- or race-based differences in proportions of patients treated were found in the Australasian cohort. White race was significantly associated with earlier treatment initiation compared with non-White race across diagnoses in the Canadian cohort, whereas the opposite association was found in the Australasian cohort.

Interpretation: Sex- and race-based differences exist in the initiation of ILD treatment, with variability across different cohorts in different countries. Reasons for these differences need to be further explored in future studies.