C-reactive protein and mortality in mild to moderate chronic obstructive pulmonary disease
- 1The James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research and St Paul’s Hospital, Vancouver, British Columbia, Canada
- 2Department of Medicine (Pulmonary Division), University of British Columbia, Vancouver, British Columbia, Canada
- 3University of Minnesota School of Public Health, Minneapolis, MN, USA
- 4University of Manitoba, Winnipeg, Manitoba, Canada
- 5Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- 6University of California at Los Angeles School of Medicine, Los Angeles, California, USA
- Correspondence to:
Dr D D Sin
James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research, St Paul’s Hospital, 1081 Burrard Street, Vancouver, BC, Canada V6Z 1Y6;
- Received 26 January 2006
- Accepted 16 May 2006
- Published Online First 31 May 2006
Background: Although C-reactive protein (CRP) levels are increased in chronic obstructive pulmonary disease (COPD), it is not certain whether they are associated with adverse clinical outcomes.
Methods: Serum CRP levels were measured in 4803 participants in the Lung Health Study with mild to moderate COPD. The risk of all-cause and disease specific causes of mortality was determined as well as cardiovascular event rates, adjusting for important covariates such as age, sex, cigarette smoking, and lung function. Cardiovascular events were defined as death from coronary heart disease or stroke, or non-fatal myocardial infarction or stroke requiring admission to hospital.
Results: CRP levels were associated with all-cause, cardiovascular, and cancer specific causes of mortality. Individuals in the highest quintile of CRP had a relative risk (RR) for all-cause mortality of 1.79 (95% confidence interval (CI) 1.25 to 2.56) compared with those in the lowest quintile of CRP. For cardiovascular events and cancer deaths the corresponding RRs were 1.51 (95% CI 1.20 to 1.90) and 1.85 (95% CI 1.10 to 3.13), respectively. CRP levels were also associated with an accelerated decline in forced expiratory volume in 1 second (p<0.001). The discriminative property of CRP was greatest during the first year of measurement and decayed over time. Comparing the highest and lowest CRP quintiles, the RR was 4.03 (95% CI 1.23 to 13.21) for 1 year mortality, 3.30 (95% CI 1.38 to 7.86) for 2 year mortality, and 1.82 (95% CI 1.22 to 2.68) for ⩾5 year mortality.
Conclusions: CRP measurements provide incremental prognostic information beyond that achieved by traditional markers of prognosis in patients with mild to moderate COPD, and may enable more accurate detection of patients at a high risk of mortality.
- BMI, body mass index
- COPD, chronic obstructive pulmonary disease
- CRP, C-reactive protein
- FEV1, forced expiratory volume in 1 second
- FVC, forced vital capacity
Published Online First 31 May 2006
This work was funded by the Canadian Institutes of Health Research (Population Health) and by contract N01-HR-46002 from the Division of Lung Diseases of the National Heart, Lung, and Blood Institute (The Lung Health Study).
Competing interests: DDS, SFM, and RW have received research funding from GlaxoSmithKline (GSK) and have received honoraria for speaking engagements from GSK and AstraZeneca.