Hypoxemia severity and survival in ILD and COPD on long-term oxygen therapy – The population-based DISCOVERY study

Abstract

Background and aim: Whether long-term oxygen therapy (LTOT) improves survival in interstitial lung disease (ILD) is unclear. A recent study reported similar survival in ILD patients with severe hypoxemia on LTOT vs. moderate hypoxemia without LTOT, and proposed that LTOT could be indicated in ILD already at moderate hypoxemia. The aim of this study was to compare survival by severity of hypoxemia in patients with ILD and COPD, respectively, treated with LTOT. Methods: A population-based, longitudinal study of adults starting LTOT for ILD or COPD 1987-2018. Transplantfree survival was compared between moderate (PaO2 7.4-8.7 kPa) and severe (PaO2<7.4 kPa) hypoxemia using Cox regression, adjusted for age, sex, BMI, smoking status, WHO performance status, year of starting LTOT, diagnosis of heart failure, ischemic heart disease and diabetes mellitus. Results: In total, 17,084 patients were included, with ILD and moderate (n = 470) or severe hypoxemia (n = 2,408), and COPD with moderate (n = 2,087) or severe hypoxemia (n = 12,119). Compared with in COPD, ILD patients on LTOT had lower transplant-free survival after one year (41.9 vs. 67.1%) and two years (20.3 vs. 46.5%). In COPD worse hypoxemia was associated with slightly increased risk of death/lung transplantation, aHR 1.07 (1.00-1.14), a difference not shown in ILD, aHR 0.91 (0.80-1.03). Conclusion: Transplant-free survival did not differ in ILD patients between moderate and severe hypoxia despite LTOT.

A study on the prevalence and prognosis of progressive pulmonary fibrosis: A retrospective observational study

“…[21][22][23] Additionally, the use of home oxygen has been reported as a significant risk factor for mortality and an important prognostic indicator in ILD patients in previous studies. [21,24,25] Accordingly, patients using home oxygen or undergoing combined therapy with a steroid and an immunosuppressant may require more proactive management because of the higher possibility of further disease progression. The introduction of alternative treatments, such as antifibrotic agents, should be actively considered based on the course of the disease.…”

“…[21–23] Additionally, the use of home oxygen has been reported as a significant risk factor for mortality and an important prognostic indicator in ILD patients in previous studies. [21,24,25]…”

Altered Lipid Profile in COVID-19 Patients and Metabolic Reprogramming

“…Interestingly, the lipid levels in patients with COPD changed and compared with the healthy population, but it was similar to patients with COVID-19. In addition, hypoxia is a common characteristic of patients that can change the metabolism ( Grieb et al, 2021 ; Palm and Ekström, 2021 ). Hence, the patients were artificially ventilated, a procedure that can cause intraoperative complications but also can remit glycolysis or further metabolic reprogramming.…”

Oxygen in interstitial lung diseases

“…The authors hypothesised that LTOT may be indicated earlier in ILD than in COPD. In response to these findings, the population-based retrospective DISCOVERY study [ 20 ] collected data from the Swedish registry on 2408 ILD patients with moderate (56–65 mmHg (7.4–8.7 kPa)) or severe (<55 mmHg (<7.4 kPa); 56–60 mmHg (7.4–8 kPa) with hypoxic damage) hypoxaemia treated with LTOT. After controlling for confounders, no difference was observed in transplant-free survival in ILD patients with moderate compared with severe hypoxaemia despite LTOT.…”