Predictors of Pulmonary Embolism in Interstitial Lung Disease With Worsening Symptoms

Overview

People with interstitial lung disease (ILD) can sometimes experience a sudden and severe worsening of their breathing. While this can be caused by a flare-up of the lung disease itself, it can also be caused by a blood clot in the lungs, known as a pulmonary embolism (PE). It is often difficult for doctors to tell the difference between these two emergencies because their symptoms, such as shortness of breath and low oxygen levels, are very similar. Traditional scoring systems used to predict blood clots are often less accurate for patients who already have chronic lung diseases like ILD. The main goal of this observational study is to find better, more reliable ways to predict which ILD patients with worsening breathing symptoms actually have a pulmonary embolism. Researchers will observe 70 adult patients with ILD who come to the hospital with a sudden worsening of their symptoms (such as shortness of breath, chest pain, or low oxygen) and who require a specific type of CT scan (Computed Tomography Pulmonary Angiography, or CTPA) as part of their standard medical care to check for blood clots. The study will compare the patients whose CT scan confirms a blood clot to those whose scan does not show a clot. By comparing these two groups, the research team will evaluate various clinical signs, routine blood tests, novel inflammatory markers, and heart/lung imaging details. Identifying strong predictors of pulmonary embolism in this specific group of patients could help doctors diagnose lung blood clots faster and more accurately, leading to better clinical decision-making and improved patient outcomes

Interstitial lung diseases (ILDs) comprise a heterogeneous group of diffuse parenchymal lung disorders characterized by inflammation and fibrosis, often leading to progressive respiratory failure. Patients with ILD carry a heightened risk of venous thromboembolism, specifically pulmonary embolism (PE), driven by chronic inflammation, endothelial dysfunction, hypoxemia, reduced mobility, and a systemic pro-thrombotic state. The development of PE in ILD patients is associated with prolonged hospitalization, increased morbidity, and poor survival outcomes. Diagnosing PE in this specific population remains clinically challenging because the acute manifestations, such as worsening dyspnea and hypoxemia, closely mimic those of an acute ILD exacerbation. Furthermore, conventional clinical prediction models, such as the Wells and Revised Geneva scores, frequently exhibit limited diagnostic accuracy in this cohort because respiratory distress and baseline hypoxia are already common underlying features of ILD. To address this diagnostic gap, this prospective observational study will evaluate patients with a confirmed diagnosis of ILD who present with an acute, unexplained worsening of respiratory symptoms and undergo Computed Tomography Pulmonary Angiography (CTPA). Comprehensive clinical, laboratory, and radiological data will be systematically collected for all participants to identify independent predictors of PE. The study workflow includes: * Clinical Scoring: Calculation of established pre-test probability and mortality risk scores, including the traditional and simplified Wells score, Revised Geneva score, Pulmonary Embolism Severity Index (PESI), and Simplified PESI (SPESI). * Laboratory Assessment: Evaluation of novel inflammatory indices, including the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR). Additional laboratory profiling includes D-dimer, C-reactive protein (CRP), serum total protein, serum albumin, renal and liver function tests, and arterial blood gas analysis to calculate the A-a oxygen gradient. * Radiological \& Echocardiographic Evaluation: High-Resolution CT (HRCT) will be used to quantify ILD disease severity and extent via the Warrick Score. CTPA scans will be analyzed for embolus location, right ventricular (RV) diameter, RV/LV diameter ratio, and main pulmonary artery diameter. When available, transthoracic echocardiography will assess RV size and systolic function, TAPSE, fractional area change, McConnell sign, the 60/60 sign, and inferior vena cava collapsibility. Through multivariable logistic regression and Receiver Operating Characteristic (ROC) curve analysis, the study will compare these parameters between patients with CTPA-confirmed PE and those with negative scans. The goal is to validate the predictive strength of these biomarkers and imaging parameters, supporting the development of a disease-specific diagnostic prediction model to enhance clinical decision-making for ILD patients.