Impact of Oxygen Therapy on Inflammatory Markers and Lung Function in Interstitial Lung Disease: A Comparative Study

Background: Interstitial lung disease (ILD) is characterized by chronic inflammation and fibrosis of the lung parenchyma, often leading to progressive hypoxemia requiring long-term oxygen therapy (LTOT). While inflammatory biomarkers are known to reflect disease activity, the impact of LTOT on these markers remains incompletely understood. Aim and Objectives: To compare serial changes in inflammatory and biochemical markers—including highsensitivity C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR), D-dimer, interleukin-6 (IL-6), procalcitonin, and lactate dehydrogenase (LDH)—in ILD patients receiving LTOT versus those not on oxygen therapy. Materials and Methods: A prospective, observational study was conducted on 112 ILD patients divided into two groups: 56 patients on LTOT and 56 without oxygen therapy. Blood samples were collected at baseline and after one month to measure hs-CRP, ESR, D-dimer, IL-6, procalcitonin, and LDH. Data were analyzed using Shapiro– Wilk test for normality, followed by appropriate parametric (independent/paired t-tests) or non-parametric (Mann–Whitney U, Wilcoxon signed-rank) tests. Correlations between post-therapy inflammatory markers, lung function (FVC), and oxygen requirement were assessed using Spearman’s rank correlation. Results: At baseline, both groups had elevated inflammatory markers, with significantly higher mean LDH and D-dimer in the LTOT group. After one month of oxygen therapy, significant reductions were observed in hs-CRP, ESR, IL-6, and D-dimer (p < 0.05), while LDH and procalcitonin also showed mild but consistent declines. Correlation analysis revealed a weak positive association between post-therapy LDH and oxygen flow rate (r = 0.62, p < 0.01), while hs-CRP and IL-6 showed minimal correlation with FVC. Conclusion: Long-term oxygen therapy in ILD patients led to a measurable reduction in systemic inflammation, as evidenced by decreased hs-CRP, IL-6, ESR, and D-dimer levels. LDH, though less specific, showed a moderate relationship with oxygen requirement, suggesting its potential role as an adjunctive marker for tissue injury and hypoxia. Monitoring LDH alongside traditional inflammatory markers may enhance clinical assessment of disease activity and therapeutic response in ILD patients on LTOT.