Prevalence and Clinical Outcome of Eosinophilic COPD

This study seeks to evaluate the clinical significance and prevalence of the eosinophilic phenotype in patients presenting with an acute exacerbation of Chronic Obstructive Pulmonary Disease (AECOPD). While elevated blood eosinophil counts have emerged as a practical biomarker for eosinophilic airway inflammation, often guiding treatment decisions, there is limited data regarding its prevalence and impact on clinical outcomes in Upper Egypt. Upon admission, enrolled patients will undergo a comprehensive clinical assessment as part of their standard care. The study procedures and data collection methods include the following: * Clinical History and Examination: Researchers will collect demographic data, smoking status (pack-years), and a history of comorbidities, such as cardiovascular diseases, diabetes, and obstructive sleep apnea. The frequency of previous exacerbations over the past 12 months will be recorded, alongside current maintenance therapies (e.g., LAMA, LABA, ICS, triple therapy, and long-term oxygen therapy). A full physical examination will be conducted to evaluate vital signs, Body Mass Index (BMI), and room air oxygen saturation. * Laboratory Investigations: A complete blood count (CBC) will be performed from a venous blood sample at admission and before discharge to measure the absolute peripheral blood eosinophil count. Arterial blood gases (ABG) will be analyzed on room air. To exclude parasitic infestations that could skew eosinophil counts, a stool analysis will be conducted. * Sputum Cytology: A single induced sputum sample will be collected following nebulization with 3% hypertonic saline. The sample will be homogenized, centrifuged, and stained to perform differential cell counts via light microscopy, allowing researchers to evaluate the correlation between sputum and blood eosinophilia. * Pulmonary Function and Radiological Assessment: Standard spirometry will be utilized to measure FEV1, FVC, and the FEV1/FVC ratio, classifying the patient's baseline COPD severity according to GOLD criteria (Mild to Very Severe). Radiological assessments will include a chest X-ray, with a CT scan performed if clinically indicated. * Exacerbation Management and Classification: The severity of the acute exacerbation will be classified (mild, moderate, or severe) based on GOLD 2026 thresholds, which incorporate dyspnea visual analog scale (VAS) scores, respiratory rate, heart rate, resting SaO2, and C-reactive protein (CRP) levels. Patients will receive standard pharmacological management for AECOPD as soon as possible, which may include short-acting bronchodilators, a short course of systemic corticosteroids, and antibiotics if purulent sputum or prior infection history is present.