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07-05-2012 | Cardiology | Article

Heart disease risk can indicate long-term COPD fate

Abstract

Free abstract

MedWire News: Knowledge of cardiovascular disease (CVD) risk significantly improves prognostication among patients with chronic obstructive pulmonary disease (COPD), study findings indicate.

The study data highlight the importance of cardiac testing in patients with COPD, say Hwa Mu Lee (University of California, Irvine, USA) and colleagues.

Writing in Chest, the researchers explain that COPD is closely associated with CVD, with each condition complicating the prognosis of the other.

They hypothesized that accurate quantification of CVD risk in patients with COPD may help better predict long-term prognosis of these patients.

To investigate whether this is the case, Lee and team determined the severity of COPD in 6266 US adults aged 40 years and older, who participated in the Third National Health and Nutrition Examination Survey, in relation to their estimated 10-year risk for CVD.

COPD was defined by spirometry, and severity was classified on the basis of forced expiratory volume in 1 second (FEV1) as mild (FEV1≥80%), moderate (50%≤FEV1<80%), or severe (FEV1<50%).

The risk for CVD was calculated using the Framingham Risk Score, which includes, age, gender, total cholesterol, high-density lipoprotein cholesterol, systolic blood pressure, treatment for hypertension, history of smoking, and diabetes (fasting glucose ≥126 mg/dL, or ≥200 mg/dL if not fasting). Individuals with a history of myocardial infarction, stroke, or heart failure were automatically classified as very high risk.

The prevalence of mild, moderate, and severe COPD among the study participants was 12.1%, 8.7%, and 1.7%, respectively.

The researchers found that the proportion of patients with high or very high CVD risk ranged from 25% in those without COPD to over 50% in those with moderate or severe COPD.

In unadjusted analyses, individuals with intermediate and high CVD risk were 2.5 and 4.5 times more likely than those with low CVD risk to have COPD, respectively.

Cardiovascular and total mortality was monitored over a mean follow-up period of 8.3 years. Lee and team observed a progressive increase in CVD and total mortality as COPD increased among individuals with high or very high CVD risk. For example, the total mortality rate was 63 per 1000 person-years among patients with mild COPD and a high CVD risk score, and 108 per 1000 person-years among those with severe COPD and a high CVD risk score.

By contrast, when CVD risk scores were low, mortality was also low (less than 10 per 1000 person-years), regardless of COPD severity.

When the researchers added CVD risk score to lung function data, they observed significant improvements in the prediction of both CVD and total mortality in COPD patients. The net reclassification improvements were 17.1% and 13.0% for CVD and total mortality, respectively. The improvements were occurred regardless of COPD severity.

"The practical implications of our study findings are that individuals with COPD at intermediate or high global CVE risk may in addition to their anti-COPD therapy require aggressive and early treatment for CVE risk reduction such as statin therapy," Lee and co-authors conclude.

By Laura Cowen

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