Blood test may aid early emphysema detection in smokers

A simple blood test performed during regular annual physical exams may help clinicians promote smoking cessation among patients who are at high risk of developing emphysema, results from a small prospective study indicate.

“We know, from other studies, that smokers who learn from objective evidence that their health is in danger are much more likely to quit,” study researcher Ronald G. Crystal, MD, professor of genetic medicine at Weill Cornell Medical College and chief in the division of pulmonary and critical care medicine at New York-Presbyterian Hospital, said in a press release.

Crystal and colleagues performed physical exams and histories, pulmonary function tests — including spirometry and diffusing capacity of the lung for carbon monoxide (DLCO) — blood and urine analysis, and imaging with ECG and X-ray in 92 study participants.

Patients were grouped by smoking status: healthy nonsmokers (n=32), healthy smokers with normal spirometry and DLCO (n=41) and smokers with early evidence of lung destruction indicated by normal spirometry and low DLCO (n=19).

The researchers found that elevated levels of endothelial microparticles (EMP), a byproduct released in the bloodstream when the capillaries surrounding the alveoli in the lungs are damaged, correlated with abnormal DLCO test results 95% of the time (P<10-4 compared with nonsmokers and P<-3 compared with healthy smokers).

Currently DLCO and chest high-resolution computed tomography (HRCT) are the only tools clinicians have to diagnose emphysema. The untreatable lung disease is one of two disorders, the other being chronic bronchitis, that make up chronic obstructive pulmonary disease (COPD) — the fourth leading cause of death in the United States.

“Assessment of EMP levels may provide an early and inexpensive approach to identifying early evidence of emphysema, without the radiation exposure associated with chest HRCT,” the researchers wrote in the American Journal of Respiratory and Critical Care Medicine.

Testing in two other groups of participants with similar health characteristics yielded matching results, and study findings stayed the same after patients with diabetes, hypertension or both were excluded from analyses.

Further studies to evaluate EMP levels in larger groups of patients are underway to validate these findings (Clinical Trial Identifiers: NCT00224198 and NCT00224185).

“Elevated EMP levels may be a useful biomarker to identify smokers with early

emphysema at a stage where intervention may prevent further permanent lung destruction,” the researchers wrote.

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