Chest
Volume 142, Issue 5, November 2012, Pages 1118-1125
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Original Research
COPD
Relation Between COPD Severity and Global Cardiovascular Risk in US Adults

https://doi.org/10.1378/chest.11-2421Get rights and content

Background

COPD is associated with the risk of cardiovascular events (CVEs), but its impact on overall mortality has not been well quantified. We determined the impact of global CVE risk assessment on CVE and total mortality in subjects with COPD.

Methods

We examined the severity of COPD in 6,266 US adult patients aged ≥ 40 years in relation to the estimated 10-year risk of CVEs. COPD was defined by spirometry, and severity was classified as mild (FEV1 ≥ 80%), moderate (50% ≤ FEV1 < 80%), or severe (FEV1 < 50%). Cox proportional hazards regression was used to evaluate the relationship of global CVE risk combined with COPD status to CVE and all-cause mortality over a mean follow-up of 98.8 ± 51.3 months.

Results

The proportion of individuals at high risk for CVEs ranged from 25% (without COPD) to > 50% (with moderate to severe COPD) (P < .05). When global CVE risk scores were low, CVE mortality was also low (< 10/1,000 person-years) regardless of COPD severity, and CVE mortality was high when CVE global risk was high (> 40/1,000 person-years). Global CVE risk improved prediction for both CVEs and total mortality in patients with COPD (P < .0001), with a net reclassification improvement of 17.1% (P < .0001) and 13.0% (P < .0001), respectively, beyond lung function measures.

Conclusions

The addition of global CVE risk scores to lung function data significantly improves risk stratification of patients with COPD for CVE and total mortality and, thus, adds to predicting long-term survival of these patients.

Section snippets

Study Sample

We used data from 6,266 individuals (projected to 66.8 million) aged ≥ 40 years who participated in the National Health and Nutrition Examination Survey III (1988-1994) in whom spirometry and CVE risk factor data were available and who did not have asthma (self-reported or physician diagnosed). The clinical and demographic data of these patients were then linked with National Death Index-linked mortality data through 2006. CVE mortality was defined by International Classification of Diseases,

Results

The prevalence of mild, moderate, and severe COPD was 12.1%, 8.7%, and 1.7%, respectively. Patients with vs without COPD had a higher mean age, systolic BP, history of smoking, and FRS, and those with severe COPD were more likely to have a family history of CVEs. They were also more likely to belong to intermediate and high global risk groups and to die of pulmonary events and CVEs. With increasing severity of COPD, FEV1, FEV1/FVC, and diastolic BP, the proportion of patients at low global risk

Discussion

The most important and novel finding in this study was that the addition of global CVE risk scores to lung function data significantly improved prognostic classification of individuals with COPD and, thus, should be used in risk stratification of patients with COPD. The findings also support previous observations that impaired lung function is a significant predictor of CVEs and mortality.19 However, by itself, measures of lung function have relatively poor resolution in predicting these events

Acknowledgments

Author contributions: Dr Lee had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Dr Lee: contributed to the study design, supervision of all project activities, and writing of the manuscript.

Ms J. Lee: contributed to the majority of analyses, interpretation of the results, and writing of the manuscript.

Ms K. Lee: contributed to additional analyses and editing of the manuscript.

Ms Luo: contributed to

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  • Cited by (0)

    Funding/Support: The authors have reported to CHEST that no funding was received for this study.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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