Pulmonary embolism in patients with interstitial lung disease admitted for acute respiratory worsening

<title>Abstract</title> <p> <bold>Introduction</bold> : Acute respiratory worsening (ARW) in interstitial lung disease (ILD) is a critical clinical event with a broad differential diagnosis. Pulmonary embolism (PE) is a potential trigger, but its prevalence, predictors, and impact in this setting remain poorly defined. <bold>Objective</bold> : To evaluate PE prevalence, clinical predictors, and prognostic significance in patients with ILD presenting with ARW. <bold>Methods</bold> : This retrospective cohort study analyzed ILD patients admitted to a tertiary center (2017–2023) for ARW who underwent CT pulmonary angiography (CTA) within 72 hours. Data was retrieved using the MDClone platform, including demographic, clinical, and laboratory variables. A non-ILD control group was matched based on age, sex, and smoking status. <bold>Results</bold> : Of 2,564 ILD admissions, 439 were due to ARW, CTA was performed in 77 (17.5%). PE was diagnosed in 14 of these (18.2%). Conventional predictors (tachycardia, hypoxemia, elevated D-dimer, malignancy, and clinical signs of deep vein thrombosis) did not differ between PE-positive and PE-negative patients. In the setting of ARW in ILD, risk of PE was significantly elevated in never-smokers compared to current or former smokers (30.6% vs. 7.3%; OR 5.43; 95% CI 1.3–21.4) and was numerically higher compared to matched controls (18.2% vs. 11.9%, p=0.11). PE was not associated with short- or long-term survival difference. <bold>Conclusion</bold> : PE was a frequent finding in ILD patients with ARW, particularly among never-smokers. Since conventional diagnostic markers and clinical prediction rules appear unreliable in this population, clinicians should maintain a low threshold for CTA to identify this potentially reversible contributor to respiratory deterioration. </p>