Investigating the Relationship between COPD Severity and Inflammatory Markers ESRe and CRP in Hospitalized Patients

3. Student Research Committee, Zabol University of Medical Sciences, Zabol, Iran

*Corresponding author: Dadkhoda Sofi, Department of Internal Medicine, School of Medicine, Zabol University of Medical Sciences, Zabol, Iran. Email: d_sofi@zbmu.ac.ir

EXTENDED ABSTRACT

Background

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disorder characterized by persistent airflow limitation and symptoms such as dyspnea, cough, sputum production, and wheezing. Long-term exposure to cigarette smoke is a major contributor to COPD, while passive smoking, air pollution, occupational dust and fumes, and other inhaled irritants may also participate in disease development and progression [1, 2]. Chronic lung damage leading to COPD has been linked particularly to prolonged smoking [3], while other inhaled exposures may also contribute [4, 5]. Clinical assessment of COPD incorporates symptoms, medical and exposure history, and complementary testing [6]. Systemic inflammation may accompany COPD and has been investigated as a marker of disease activity, severity, exacerbation, and prognosis. Erythrocyte sedimentation rate (ESR) is a nonspecific marker influenced by acute-phase proteins and changes in red blood cell aggregation, whereas C-reactive protein (CRP) is an acute-phase protein released in response to inflammatory stimuli [8]. Previous studies cited in the source article have reported associations between increased inflammatory markers and advanced COPD, functional impairment, frequent exacerbation, or mortality, although findings have not been entirely consistent across populations [8-14]. The present study was therefore conducted to determine the relationship of ESR and CRP with COPD severity and clinical outcome among hospitalized patients.

Methods

This descriptive-analytical study included patients with COPD admitted to the internal medicine ward of Amir al-Momenin Hospital in Zabol during 1401-1402. COPD was diagnosed by internal medicine specialists. Patients with a history of collagen vascular disease, lung or other malignancy, heart failure, COVID-19, AIDS, active infection, or tuberculosis were excluded. Clinical and exposure information was extracted from medical records and a researcher-designed checklist. A complete history was obtained during hospitalization, including current or previous cigarette smoking, inhaled opium use, and duration of exposure to fossil fuels, particularly among patients exposed during household cooking. ESR and CRP were measured at admission in addition to routine laboratory testing, and the duration of hospitalization and outcome were recorded. Disease severity was classified into three categories according to the criteria used in the source study: mild COPD was defined by dyspnea during heavy activity with mild airflow limitation; moderate COPD by dyspnea during moderate activity with limited impairment in daily activities; and severe COPD by dyspnea while walking on level ground with limitation of routine daily activities. Data were analyzed in SPSS version 22. Descriptive statistics included frequency, mean, and standard deviation. Chi-square, Fisher exact, independent t, and Mann-Whitney tests were used as appropriate. Receiver operating characteristic (ROC) curve analysis was used to evaluate the ability of ESR and CRP to predict disease severity and outcome. Statistical significance was defined as P<0.05. The study was approved by the Research Ethics Committee of Zabol University of Medical Sciences (IR.ZBMU.REC.1402.045), and patient information was handled confidentially.

Results

A total of 200 hospitalized patients with COPD were evaluated; 95 (47.5%) were men and 105 (52.5%) were women. Patients older than 60 years represented 56% of the study population, those aged 45-60 years represented 34.5%, and patients younger than 30 years represented 1%. Mild COPD was the most frequent severity category (44.5%), followed by moderate COPD (33%) and severe COPD (22.5%). The article reports that 16.5% of the patients died during hospitalization. The overall mean ESR was 54.68 with a standard deviation of 81.49, and the overall mean CRP was 1.50 with a standard deviation of 1.02.

Inflammatory marker levels differed significantly according to clinical outcome. Mean ESR was 46.41±28.98 in patients who were discharged and 54.96±77.32 in patients who died; this difference was statistically significant (P=0.0001). Mean CRP was 1.29±0.93 among discharged patients and 2.54±0.83 among those who died, again with a statistically significant difference (P=0.0001). Thus, both markers were higher in patients with an unfavorable hospital outcome.

A clear gradient was also observed across COPD severity categories. Mean ESR increased from 26.46±6.51 in mild COPD to 54.60±15.83 in moderate COPD and 110.62±16.06 in severe COPD, with a statistically significant difference among the three groups (P=0.0001). CRP showed a similar stepwise increase: mean values were 0.61 in mild COPD, 1.75 in moderate COPD, and 2.86 in severe COPD, and the between-group difference was statistically significant (P=0.0001). These results indicate progressively higher systemic inflammatory marker levels with greater clinical severity.

Table 3. Comparison of mean ESR according to COPD severity.

ROC analysis demonstrated high discriminatory performance of both markers for predicting COPD severity. The area under the ROC curve was 0.994 for ESR and 0.971 for CRP. These values indicate that, within the population studied, both ESR and CRP were strongly associated with severity classification, with ESR showing the numerically higher AUC. The source article also interprets the outcome analyses as showing significant relationships of both ESR and CRP with COPD outcome. In its discussion, the study relates the observed findings to previous reports in which elevated CRP was associated with functional impairment or mortality and increased ESR and CRP were observed among patients with more severe COPD or recurrent exacerbations [9, 11, 12, 14]. Other studies cited by the authors reported less consistent associations in stable COPD populations [8, 10, 13], emphasizing that inflammatory marker performance may vary according to the clinical population and study context. The authors identified incomplete medical records requiring replacement with complete records as an implementation limitation.

Conclusion

Among hospitalized patients with COPD, ESR and CRP were significantly associated with both disease severity and hospital outcome. Both markers increased substantially from mild to severe disease, and levels were higher among patients who died than among those discharged. ESR and CRP also demonstrated high AUC values for discrimination of COPD severity. Within the conditions of this study, these routinely available inflammatory markers may therefore provide useful adjunctive information for assessing the severity and prognosis of hospitalized patients with COPD.

Keywords: Blood Sedimentation, C-Reactive Protein, Chronic Obstructive Pulmonary Disease

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