Emphysema and Airway Wall Thickness affect Mortality
Although computed tomography (CT) has been used to measure the thickness of airway walls (AWT) and degree of emphysema, the prognostic value of these CT measures on morality had never been studied before. A recent study, published in the latest issue of American Thoracic Society's American Journal of Respiratory and Critical Care Medicine, has found the association between CT- measured emphysema and AWT and eight years mortality.
The study was led by Ane Johannessen, a post-doctoral researcher at Haukeland University Hospital in Bergen, Norway. For the study, 947 ever smokers with or without COPD were followed up for a period of 8 years. All the participants were made to undergo spirometry and CT scanning. On the basis of percentage of low attenuation areas in the lungs as seen during a CT scan, the degree of emphysema in the participants was categorized as low, medium or high. The diagnosis of COPD was made based on level of airway obstruction seen during spirometry. Among all the participants, 462 were diagnosed with COPD. 568 participants had low degree of emphysema, 190 had medium degree and 189 had high degree of emphysema.
During follow-up, it was seen that 4% of the patients suffering from low degree of emphysema expired compared to 18% suffering with medium degree emphysema and 44% of those suffering from high degree emphysema. After taking care of factors like sex, BMI, habit of smoking, measurement of lung function and diseases like COPD, it was seen that patients with low emphysema survived 19 months longer than patients with medium and high degree of emphysema for all-cause mortality. In case of patients with severe emphysema, increased thickness of the airways reduced survival time.
In severe emphysema, survival is 33 months less for respiratory mortality; and 37 months less for cardiovascular mortality, compared to low degree emphysema. The researchers have opined that considering the large number of CT scans being done annually around the world, their predictive value in the prognosis of mortality risk can be used to target the patients for specific therapeutic interventions.
Editor: Dr. Bimal Rajalingam MBBS DNB (Resp Med)
Saturday, November 14, 2015