Delayed diagnosis and use of oxygen therapy are associated with worse outcomes in patients with fibrotic ILD

Two posters presented earlier this month at the CHEST 2024 annual meeting in Boston, Massachusetts, highlight that delays in diagnosis of fibrotic interstitial lung disease (ILD) may shorten overall survival (OS) while supplemental oxygen therapy (O2) may increase their clinical burden, leading to higher rates of acute exacerbations and hospitalizations.

Impact of late diagnosis on overall survival of patients with fibrotic ILD

The first poster assessed the real-world impact of delayed diagnosis of fibrotic ILD on overall survival.¹ The researchers emphasized that the diagnosis of ILD is often delayed due to problems in differentiating common symptoms and/or referring patients to pulmonologists; this results in a delay in the initiation of appropriate treatment and regular monitoring of respiratory diseases. However, the extent of these delays and their impact on patient outcomes is not fully understood.

To study the impact of delayed diagnosis, the researchers used Henry Ford Health administrative and electronic health records for patients over 18 years of age who met criteria for fibrotic ILD and were enrolled in the Health Alliance Plan (HAP) for a 5-year period before treatment. diagnostic period. They determined the date of onset of patients’ earliest symptoms associated with ILD during the 5-year period before diagnosis based on chart review and classified time of diagnosis as timely (6 months or less from earliest symptom) or delayed (less than 6 months from the earliest symptom). months from earliest symptom).

The researchers estimated OS, defined as the interval (in months) between the date of diagnosis and death, using the weighted Kaplan-Meier methodology. In addition, they estimated the mortality rate, which they expressed per 100 person-years (PY), using the total duration of enrollment after the date of diagnosis as the “at-risk” time.

Of the 238 patients who met all eligibility criteria, 57.6% (n = 137) were diagnosed late and 42.2% (n = 101) were diagnosed timely. Additionally, a larger proportion of participants in the delayed cohort died during follow-up (60%) compared with those in the timely cohort (50%; P = .23).

Thus, mortality rates were 16.6 (95% CI, 14.0-19.6) per 100 years and 12.5 (95% CI, 10.4-14.9) per 100 years in the delayed and timely cohorts respectively (incidence rate ratio (IRR) 1.33). 95% CI, 1.04-1.70; P = 0.021). Finally, the investigators found that survival duration was nominally shorter among the delayed treatment cohort (median 52.7 months; 95% CI 38.1–69.8) compared with the prompt treatment cohort (median 70.7 months; 95% CI 33.8–104.2).

“Given the observed detrimental impact of late diagnosis on survival, increased attention should be paid to earlier clinical recognition of fibrotic ILD,” the authors concluded. “Predictors of delayed diagnosis need to be developed and validated to ensure early identification of patients with ILD.”

Impact of supplemental oxygen therapy on outcomes of fibrotic ILD

Based on the previous author’s findings on the impact of late diagnosis of ILD on patient outcomes, the second bench assessed the impact of O2 therapy on clinical outcomes among patients newly diagnosed with fibrotic ILD.² Despite the frequent use of O2 in this population, the researchers noted a lack of studies evaluating the impact of O2 therapy on patient outcomes.

Therefore, they analyzed the effect of treatment on patient outcomes using the Optum Market Clarity database from October 1, 2015 to June 30, 2022. Eligible patients were over 18 years of age with two or more diagnoses of ILD fibrosis on different dates within the past year. The researchers matched those who started O2 therapy after ILD diagnosis (exposed group) in a 1:1 ratio with those who had not yet started O2 therapy (unexposed group).

Patients were followed until disenrollment from the health plan, death, or end of the study period; Hospitalizations and acute exacerbations during follow-up were compared between cohorts. In addition, the researchers defined disease progression as a relative decline in forced vital capacity (FVC) of 10% between the pre-index period and the follow-up period.

So the researchers matched 24,680 patients who started O2 therapy with 24,680 patients who did not. During the follow-up period, they found that a significantly higher percentage of the exposed cohort experienced acute exacerbations than the unexposed cohort (7.3% vs. 4.4%; P <0.001). Similarly, at 12 months after the index date, the exposed cohort had a higher rate of all-cause hospitalizations (41.4% vs. 31.7%; P <0.001) than in the non-irradiated cohort.

Additionally, the researchers found that the exposed cohort had a shorter mean time to first all-cause hospitalization (20.8 vs. 35.9 months); a similar trend was observed for fibrotic ILD-related hospitalizations. Finally, among the 162 exposed and 110 unexposed patients with FVC results, more exposed patients experienced disease progression (14.2% vs. 13.6%; P = 0.889); however, this difference was not significant.

“Although O2 therapy is a common treatment for patients with fibrosing ILD, it may be clinically burdensome for patients in the long term,” the authors concluded. “This suggests that future treatments that reduce the need for O2 therapy could potentially improve clinical outcomes among patients with fibrosing ILD.”

Taken together, the results of both posters highlight the urgent need for early diagnosis of fibrotic ILD and exploration of alternative treatments that may reduce the long-term clinical burden associated with O2 supplementation.

Links

1. Shetty S, Berger A, Shah S, et al: Real-world impact of delayed diagnosis of fibrotic interstitial lung disease on overall survival. Poster presented at CHEST 2024 Annual Meeting; October 6–9, 2024; Boston, Massachusetts. doi:10.1016/j.chest.2024.06.2101
2. Yang J, Steffens A, Olson A, et al. Effect of supplemental oxygen therapy on clinical outcomes in patients with fibrosing interstitial lung disease in the United States. Poster presented at CHEST 2024 Annual Meeting; October 6–9, 2024; Boston, Massachusetts. doi:10.1016/j.chest.2024.06.2072