C-reactive protein in patients with COPD, control smokers and non-smokers

TLDR

Patients with COPD exhibit elevated serum C‑reactive protein, likely reflecting systemic inflammation rather than smoking or ischemic heart disease. The study aimed to determine whether ischemic heart disease or smoking account for raised CRP in COPD and to assess the impact of inhaled corticosteroid use on CRP levels. Cross‑sectional analyses compared 88 COPD patients, 33 smokers, and 38 non‑smokers, measuring medical history, pulmonary function, exercise capacity, and high‑sensitivity serum CRP. COPD patients had markedly higher CRP than controls, showed no unstable IHD, and had lower CRP when treated with inhaled corticosteroids, indicating that elevated CRP is independent of smoking and IHD.

Abstract

<b>Background:</b> Patients with chronic obstructive pulmonary disease (COPD) have raised serum levels of C reactive protein (CRP). This may be related directly to COPD and its associated systemic inflammation or secondary to other factors such as concomitant ischaemic heart disease (IHD) or smoking status. The aim of this study was to evaluate IHD and smoking as potential causes of raised CRP levels in COPD and to test the association between inhaled corticosteroid (ICS) use and serum CRP levels. <b>Methods:</b> Cross sectional analyses comparing cohorts of 88 patients with COPD, 33 smokers (S), and 38 non-smoker (NS) controls were performed. Clinical assessments included a complete medical history, pulmonary function, 6 minute walk test (6MWT), cardiopulmonary exercise test, and high sensitivity serum CRP measurements. <b>Results:</b> Serum CRP levels were significantly higher in patients with COPD (5.03 (1.51) mg/l) than in controls (adjusted odds ratio 9.51; 95% confidence interval 2.97 to 30.45) but were similar in the two control groups (S: 2.02 (1.04) mg/l; NS: 2.24 (1.04) mg/l). There was no clinical or exercise evidence of unstable IHD in any of the subjects. CRP levels were lower in COPD patients treated with I.C.S. (3.0) mg/l <i>v</i> 6.3 (3.6) mg/l); this association was confirmed in an adjusted regression model (p&lt;0.05). <b>Conclusion:</b> CRP levels are raised in COPD patients without clinically relevant IHD and independent of cigarette smoking, and reduced in patients with COPD using I.C.S. CRP may be a systemic marker of the inflammatory process that occurs in patients with COPD.