Red Blood Cell and Platelet Indices for Predicting Outcomes in Acute Exacerbations of COPD

Chronic Obstructive Pulmonary Disease (COPD) is a progressive respiratory disorder characterized by persistent airflow limitation and a heightened inflammatory response in the airways. While traditionally viewed strictly as a pulmonary condition, COPD is now widely understood to encompass systemic inflammation, oxidative stress, and immune dysregulation. The clinical trajectory of COPD is frequently punctuated by acute exacerbations (AECOPD), defined as a sudden and severe worsening of respiratory symptoms. These exacerbations accelerate lung function decline, increase the risk of acute respiratory failure (ARF), and are associated with recurrent hospitalizations and high mortality rates.

During an AECOPD, patients experience high-grade systemic inflammation, which is typically reflected by elevated conventional markers such as C-reactive protein (CRP). However, there is a pressing clinical need for more accessible, rapid, and cost-effective biomarkers to aid in early risk stratification upon hospital admission.

Routine hematological analysis, specifically the complete blood count (CBC), offers several promising, non-invasive prognostic markers.

Red Cell Distribution Width (RDW) is a quantitative measure of anisocytosis (variability in red blood cell size). Evidence indicates that elevated RDW is not just a marker of anemia, but reflects underlying chronic inflammation, oxidative stress, and impaired erythropoiesis. In COPD, elevated RDW has been correlated with disease severity, hypercapnia, prolonged hospital stays, and increased risk of in-hospital and ICU mortality.

Furthermore, platelets are critical mediators in inflammatory processes and endothelial dysfunction. Platelet activation plays a role in the pathophysiology of COPD exacerbations. Inflammatory cytokines can interfere with megakaryopoiesis, altering platelet production and activation dynamics. Consequently, indices such as Mean Platelet Volume (MPV), Platelet Distribution Width (PDW), Plateletcrit (PCT%), and the Platelet Large Cell Ratio (P-LCR) undergo significant changes during an acute exacerbation.

Despite this evidence, the combined clinical utility of RDW and specific platelet indices in predicting distinct severity grades and clinical outcomes in real-world AECOPD management remains incompletely defined.

This prospective cohort study aims to evaluate the combined prognostic utility of these basic hematological indices. Patients admitted to the Chest Diseases and Tuberculosis Department with a primary diagnosis of AECOPD will be evaluated.

Upon enrollment, all participants will undergo a comprehensive clinical assessment, including a detailed medical history and physical examination. Dyspnea severity will be clinically graded.

The diagnostic and assessment workflow includes:

• Laboratory Investigations: A comprehensive metabolic and hematological panel will be drawn, focusing heavily on RBC indices (MCV, MCH, MCHC, RDW, Hct), Platelet Indices (PDW, PCT, MPV), and inflammatory ratios (Lymphocyte-to-Monocyte and Lymphocyte-to-Neutrophil ratios). Additional tests include kidney and liver function tests, coagulation profiles, ESR, and CRP.
• Arterial Blood Gases (ABG): To assess respiratory failure status and gas exchange parameters (PaO2, PaCO2, SaO2, HCO3).
• Pulmonary Function Tests (PFTs): To quantify airflow limitation (FEV1, FVC, and FEV1/FVC ratio) in accordance with the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines, as patient condition permits.
• Radiological Assessment: High-Resolution Computed Tomography (HRCT) of the chest will be utilized as a non-invasive tool to characterize anatomical changes and identify further COPD phenotypes or complications.

Inclusion criteria

• Patients above 18 years admitted to the department with AECOPD defined as an event characterized by increased dyspnea and/or cough and sputum that worsens in ≤14 days.

Exclusion criteria

• Primary reason for admission other than AECOPD.
• The patient has a diagnosis of connective tissue disorder, inflammatory bowel disease, or hematological system diseases (such as malignancy, thalassemia, hemolytic anemia).