ILD treatment differs by sex, race across countries

Key takeaways:

• More men vs. women received ILD treatment in Canada; the opposite was observed in Chicago.
• ILD treatment started earlier in white vs. nonwhite patients in Canada, but this differed in Australasia and Chicago.

The prevalence of patients with interstitial lung disease who receive treatment varied across countries, with some sex- and race-based differences, according to results published in CHEST.

“We have shown that ILD care, specifically treatment initiation, varies substantially across countries and registries,” Deborah Assayag, MD, assistant professor in the department of medicine at McGill University, and colleagues wrote. “Patient sex and race may have a significant impact on the decision to initiate ILD treatment.”

In an observational study, Assayag and colleagues analyzed 4,572 patients with ILD from three longitudinal prospective registries, each in a different location (Canada, Chicago and Australasia), to determine if the prevalence of ILD treatment receipt (antifibrotics and immunomodulating medications) differed based on sex assigned at birth and race.

Within the total cohort, the Canadian group made up most of the patients (n = 3,060; mean age, 63 years; 1,608 women; 78% white), whereas the Chicago cohort (n= 1,046; mean age, 63 years; 560 women; 64% white) and the Australasian cohort (n = 466; mean age, 68 years; 184 women; 82% white) contributed fewer patients.

Overall, patients in the Australasian cohort had the highest prevalence of treatment receipt (71%), followed by the Chicago cohort (61%) and the Canadian cohort (43%).

Across the three cohorts, idiopathic pulmonary fibrosis was more common in men, and connective tissue disease (CTD)-ILD and hypersensitivity pneumonitis were more common in women, according to researchers.

Sex-based differences

When evaluating sex-based differences in ILD treatment, researchers found that more men vs. women (47% vs. 40%; P < .001) received treatment in the Canadian cohort, with the opposite finding in the Chicago cohort, where more women received treatment (64% vs. 56%; P = .005).

Divided by ILD diagnosis, the significant sex-based differences favoring men observed in the Canadian cohort appeared most pronounced among those with IPF (55% vs. 46%; P = .02) and those with CTD-ILD (47% vs. 41%; P = .04), whereas the differences observed in the Chicago cohort favoring women only continued among those with unclassifiable ILD (51% vs. 38%; P = .013).

The prevalence of treatment did not significantly differ between men and women in the Australasian cohort.

Race-based differences

The impact of race on ILD treatment also differed across the Canadian and Chicago cohorts, with more white patients treated than nonwhite patients (46% vs. 36%; P < .001) in the Canadian cohort and more nonwhite patients treated than white patients (69% vs. 56%; P = .005) in the Chicago cohort. The significant differences favoring white patients observed in the Canadian cohort continued among those with IPF (53% vs. 35%; P = .001) and those with CTD-ILD (47% vs. 37%; P = .003), and the differences favoring nonwhite patients observed in the Chicago cohort also continued in those with CTD-ILD (70% vs. 52%; P = .009).

Similar to sex, researchers observed no race-based differences among Australasian patients.

Researchers also evaluated how sex and race were related to time to treatment initiation using Cox proportional analysis, with differences found only based on race, according to researchers.

Among Canadian patients, ILD treatment started earlier among white patients vs. nonwhite patients (median, 28 days vs. 153 days after registry visit; P = .04); however, nonwhite patients received earlier treatment in the Australasian cohort (median, 5 days vs. 57 days: P < .001) and Chicago cohort (median, 0 days vs. 210 days; P < .001).

In an analysis that accounted for sex, age, FVC percent predicted, and diffusing capacity of the lungs for carbon monoxide (DLCO) percent predicted, researchers additionally found that white patients in the Canadian cohort specifically with IPF had a greater likelihood for early treatment than white patients without IPF (HR = 2.07; 95% CI, 1.23-3.48). White patients vs. nonwhite patients without IPF still had a higher likelihood for early treatment (HR = 1.6; 95% CI, 1.13-2.25).

When assessing the Australasian cohort with the same adjustments, white patients had a decreased likelihood for early treatment than nonwhite patients (HR = 0.54; 95% CI, 0.3-0.97).

Further, researchers found that reduced FVC and DLCO percent predicted were significantly linked with earlier treatment within the three cohorts and for almost all ILD diagnoses.

“Substantial heterogeneity exists in treatment initiation for interstitial lung disease across prospective cohorts,” Assayag and colleagues wrote. “Although patient sex and race influence treatment in some cases, further research needs to explore the reasons behind geographical and sex- and race-based discrepancies.”