Recurrence risk factors for organizing pneumonia: a single-center retrospective cohort study

<bold>Introduction:</bold> Organizing pneumonia (OP) carries a favorable life prognosis, but its recurrence significantly diminishes patients’ quality of life. The risk factors associated with OP recurrence remain unclear. <bold>Objectives:</bold> This study aims to identify risk factors for OP recurrence to understand its prognosis and inform treatment strategies. <bold>Methods:</bold> We included patients with OP diagnosed by chest imaging and pathological findings who received steroid treatment at Kameda Medical Center, from April 2004 to March 2023. Patient demographics, laboratory findings, imaging results, and outcomes were assessed. Logistic regression analysis was employed to calculate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for recurrence-associated risk factors. <bold>Results:</bold> The study included 108 patients, with a median age of 69.5 years (59% men), of whom 43 (40%) experienced recurrence. Disease distribution included cryptogenic OP in 49 cases, drug-induced OP in 24 cases, and other secondary OP in 35 cases. AORs of recurrence highlighted the following: age > 69.5 years 1.57 (95%CI; 0.64–3.86), alkaline phosphatase > 215.5U/L 1.28 (95%CI; 0.48–3.39), C-reactive protein > 3.45mg/dL 1.37 (95%CI; 0.53-3.59), men 1.13 (95%CI; 0.43-3.00), krebs von den lungen-6 (KL-6) > 423.3U/mL 1.95 (95%CI; 0.74–5.11, p=0.176), and drug-induced OP 0.24 (95%CI; 0.07–0.79, p=0.019). Notably, drug-induced OP significantly reduced recurrence risk, while KL-6 levels > 423.3U/mL were marginally linked to increased recurrence risk. <bold>Conclusion:</bold> Our findings indicate a significant association between drug-induced OP and reduced recurrence risk. Conversely, elevated KL-6 levels may predict higher reccurence risk.