C-reactive protein as a biomarker of response to inhaled corticosteroids among patients with COPD

Aims: C-reactive protein (CRP) is an important biomarker in systemic inflammation in COPD; reports have suggested inhaled corticosteroids (ICS) attenuate CRP levels. We evaluated the risk of moderate-to-severe exacerbations, severe exacerbations and all-cause mortality among patients with COPD currently exposed to Inhaled corticosteroids (ICS) stratified by CRP levels compared to never ICS users with low CRP levels. Methods: We included subjects age 40 or more who had a diagnosis of COPD from January 1, 2005 to January 31, 2014 from the UK Clinical Practice Research Datalink (CPRD). ICS exposure was determined time-dependently, as current, recent, past or never users. We evaluated the risk of moderate-to-severe exacerbations, severe exacerbations and all-cause mortality among ICS users stratified by CRP levels. Results: 17,722 subjects diagnosed with COPD met the inclusion criteria. Among current or never ICS with elevated CRP levels we found, no significantly reduced risk of moderate-to-severe or severe exacerbations. For patients currently exposed ICS with CRP levels >= 8 mg/L there was no reduced risk of moderate-to-severe exacerbations (adjusted hazard ratio [adj. HR] 0.99; 95% confidence interval [CI] 0.76-1.31) or severe exacerbations (adj.HR 1.52; 95% CI 0.71-3.27). However, we found an increased risk of all-cause mortality among COPD patients with CRP levels >= 8 mg/L irrespective of ICS exposure. Conclusion: We did not find a reduced risk of moderate and/or severe COPD exacerbations among COPD patients with varying CRP levels currently exposed to ICS. However, low-grade systemic inflammation was associated with all-cause mortality among COPD patients.