Association Between C-Reactive Protein Levels with Severity and Outcome of Chronic Obstructive Pulmonary Disease: A Cross-Sectional Study

Abstract

Background: Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of morbidity and mortality worldwide, characterized by chronic inflammation and progressive airflow limitation. While spirometry remains the diagnostic cornerstone, it fails to capture the systemic inflammatory burden, highlighting the need for accessible biomarkers. C-Reactive Protein (CRP), a sensitive marker of systemic inflammation, has shown potential in reflecting disease severity and predicting adverse outcomes, yet regional evidence from low-resource settings remains limited. Objective: To evaluate the association between CRP levels and clinical indicators of COPD severity, including dyspnea grade, breathlessness level, and exacerbation frequency, among patients attending a tertiary care facility. Methods: This cross-sectional observational study was conducted at Medical Unit 3, Sheikh Zayed Hospital, Rahim Yar Khan, Pakistan, from December 2024 to March 2025. A total of 138 clinically and spirometrically diagnosed COPD patients aged ≥40 years were recruited using non-probability consecutive sampling. Patients with acute infections, malignancies, recent surgeries, or autoimmune conditions were excluded. Data were collected via structured questionnaires, the modified Medical Research Council (mMRC) dyspnea scale, and high-sensitivity CRP (hs-CRP) assays. Ethical approval was obtained from CPSP (Ref No: CPSP/REU/MED-2021-110-18581) in accordance with the Declaration of Helsinki. Statistical analyses, including ANOVA and Chi-square tests, were performed using SPSS v27. Results: Elevated CRP levels were significantly associated with higher dyspnea grades (χ² = 17.64, p = 0.040), increased breathlessness severity (χ² = 13.56, p = 0.035), and frequent exacerbations (χ² = 14.22, p = 0.027). Patients in moderate and high CRP groups experienced more clinically significant limitations and disease instability compared to those with normal CRP. Conclusion: CRP is a valuable, low-cost biomarker reflecting systemic inflammation in COPD and correlates with symptom severity and exacerbation risk. Its integration into routine COPD evaluation could enhance risk stratification, early intervention, and personalized care, particularly in resource-constrained settings.