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Biomarkers for Chronic Obstructive Pulmonary Disease (COPD)

Posted Apr 18 2012 12:00am

I tend to think of "exotic" biomarkers as relevant mainly for the screening and diagnosis of malignant neoplasms. However, a recent note in Dr. Mark Pool's Daily Sign Out blog caused be to think somewhat differently about this category of lab tests (see: Biomarkers in COPD ). Here's a excerpt from it:

Chronic obstructive lung disease (COPD) is defined functionally as airflow limitation that is not fully reversible.  It is a MAJOR cause of morbidity and mortality in the U.S. and worldwide.  COPD has two distinct major, but often coexisting, forms that represent different manifestations of COPD: emphysema and chronic bronchitis.....Treatment is focused on preventing progression of disease and the development of acute exacerbations, which are a major cause of hospitalizations, morbidity and mortality.  Common to both major forms is small airways inflammation and an abnormal inflammatory response either in large airways (chronic bronchitis) or in alveoli (emphysema). 

COPD is also associated with low-grade systemic inflammation and biomarkers that could predict increased risk for mortality from progressive disease or acute exacerbations might be greatly beneficial in providing more intensive surveillance and treatment of this group.  A team of researchers...screened blood samples from people in the ECLIPSE [study] to see if inflammatory biomarkers could predict disease outcome....Serum or plasma levels of fibrinogen, chemokine ligand 18, surfactant protein D, C-reactive protein, Clara cell secretory protein-16, interleukin-6, IL-8, and tumor necrosis factor-alpha were measured at recruitment and at subsequent visits. The addition of a panel of biomarkers significantly improved predictive power and was able to better predict outcomes compared with current clinical variables, including age, BODE index, and hospitalization history. The addition of IL-6 provided the most improvement of discriminatory power, but this was improved further with the addition of all biomarkers measured.

My first thought when I read Mark's note was that diagnosis of COPD should be rather obvious, certainly in advanced cases. Even early cases perhaps could be be predicted in patients who are heavy smokers and with family history of pulmonary disease. However, I then noticed Mark's sentence above: treatment is focused on preventing progression of disease and the development of acute exacerbations, which are a major cause of hospitalizations, morbidity and mortality. Certainly not all heavy smokers go on to develop COPD. If biomarkers could correctly identify those patients with a high likelihood of developing COPD, it's possible that early intervention could forestall the chronic form of the disease. It might also be possible that an early diagnosis could provide more of an incentive for these patients to stop smoking. Of course, some COPD patients have never smoked.

Here's an interesting excerpt from an article about COPD in Bangladesh (see: COPD to be the 3rd largest killer by 2030 ). We tend to forget that the etiology of diseases can vary in other countries. In Bangladesh, COPD is most commonly caused by indoor air pollution and childhood infections:

Experts identified increased use of tobacco...., indoor air pollution specially through cooking on cow dung and wooden fire, using kerosene stoves for cooking, exposure to occupational dusts and chemicals...., [and] frequent lower respiratory infections during childhood are the major risk factors for developing COPD. Until recently, healthcare professional believe that tobacco smoking is the key reason behind COPD. However, a recent study conducted at 22 villages of Pune in India revealed that at least 93 per cent of those who had COPD were non-smokers. They find indoor air pollution key reason linked to COPD there....Although there is no cure for COPD, we can prevent development of COPD by reducing risk factors like reducing tobacco use, air pollution.....COPD is one of the most common causes of hospitalisation in Bangladesh. Moreover, almost 90 percent deaths from COPD occur in low- and middle-income countries like Bangladesh.

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