Delayed Diagnoses, Oxygen Therapy Use Linked to Worse Outcomes in Patients With Fibrotic ILD

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

Delays in diagnosing fibrotic interstitial lung disease (ILD) can negatively impact overall survival, while supplemental oxygen therapy may exacerbate clinical burdens through increased rates of acute exacerbations and hospitalizations. | Image Credit: PH alex aviles - stock.adobe.com

Impact of Delayed Diagnoses on Overall Survival in Patients With Fibrotic ILD

The first poster assessed the real-world impact of delayed fibrotic ILD diagnoses on OS.¹ The researchers highlighted that diagnosing ILD is often delayed due to challenges in differentiating common symptoms and/or referring patients to pulmonologists; this leads to delayed initiation of appropriate treatments and routine respiratory follow-up. However, the extent of these delays and their impact on patient outcomes is not fully understood.

To explore the impact of delayed diagnoses, the researchers used Henry Ford Health administrative and electronic medical record data for patients older than 18 who met the criteria for fibrotic ILD and were enrolled in a Health Alliance Plan (HAP) for the 5-year pre-diagnosis period. They identified the date of patients’ earliest ILD-related symptom during the 5-year pre-diagnosis period based on chart review and categorized the time to diagnosis as either timely (6 months or less from the earliest symptom) or delayed (less than 6 months from the earliest symptom).

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

Of the 238 patients who met all selection criteria, 57.6% (n = 137) experienced delayed diagnosis, while 42.2% (n = 101) experienced a timely diagnosis. Additionally, a greater proportion of those in the delayed cohort died during follow-up (60%) compared with those in the timely cohort (50%; P = .23).

Therefore, the mortality rates were 16.6 (95% CI, 14.0-19.6) per 100 PY and 12.5 (95% CI, 10.4-14.9) per 100 PY in the delayed and timely cohorts, respectively (incidence rate ratio [IRR], 1.33; 95% CI, 1.04-1.70; P = .021). Lastly, the researchers found that OS duration was nominally shorter among the delayed cohort (median, 52.7 months; 95% CI, 38.1-69.8) compared with the timely cohort (median, 70.7 months; 95% CI, 33.8-104.2).

“Given the observed deleterious impact of delayed diagnosis on survival, increased attention should be given to earlier clinical recognition of fibrotic ILDs,” the authors concluded. “Predictors of delayed diagnosis should be developed and validated to enable early identification of patients with ILD.”

Effects of Supplemental Oxygen Therapy on Fibrotic ILD Outcomes

Building on the previous poster’s findings on the impact of delayed ILD diagnoses on patient outcomes, the second poster evaluated the effect of O2 therapy on clinical outcomes among patients newly diagnosed with fibrotic ILD.² Despite its frequent use in this population, the researchers noted a lack of studies evaluating the impact of O2 therapy on patient outcomes.

Therefore, they analyzed the treatment’s impact on patient outcomes using the Optum Market Clarity database from October 1, 2015, to June 30, 2022. Eligible patients were older than 18 years with 2 or more fibrotic ILD diagnoses on different dates within the past year. The researchers matched those who initiated O2 therapy following an ILD diagnosis (exposed cohort) 1:1 with those who had not yet initiated O2 therapy (unexposed cohort).

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

Consequently, the researchers matched 24,680 patients who initiated 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 < .001). Similarly, 12 months after the index date, the exposed cohort had a higher rate of all-cause hospitalizations (41.4% vs 31.7%; P < .001) than the unexposed cohort.

Also, the researchers found that the exposed cohort had a shorter median time to the first all-cause hospitalization (20.8 vs 35.9 months); a similar trend was observed for fibrotic ILD-related hospitalizations. Lastly, among 162 exposed patients and 110 unexposed patients with FVC results, a higher amount of the exposed cohort experienced disease progression (14.2% vs 13.6%; P = .889); however, this difference was not significant.

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

Together, the findings from both posters underscore the critical need for earlier diagnosis of fibrotic ILD and the exploration of alternative therapies that may reduce the long-term clinical burden associated with supplemental O2 use.

References

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 Annual Meeting 2024; October 6-9, 2024; Boston, MA. doi:10.1016/j.chest.2024.06.2101
2. Yang J, Steffens A, Olson A, et al. Impact of supplemental oxygen therapy on clinical outcomes in patients with fibrosing interstitial lung disease in the United States. Poster presented at: CHEST Annual Meeting 2024; October 6-9, 2024; Boston, MA. doi:10.1016/j.chest.2024.06.2072