Quantitative CT helps predict rapid lung function decline in smokers
MedWire News: Quantitative computed tomography (CT) evidence of lung overinflation significantly predicts rapid lung function decline in smokers with normal FEV1, researchers have found.
Writing in the journal Thorax, Harvey Coxson (Vancouver General Hospital, British Columbia, Canada) and team explain that while smoking is the main risk factor for the development of chronic obstructive pulmonary disease (COPD), only a minority of smokers eventually develop the condition.
To investigate whether quantitative CT measurements of lung inflation can help identify smokers at high risk for COPD, the team studied 143 smokers, aged between 45 and 72 years, who were enrolled in a lung cancer screening trial.
All the participants had a smoking history of at least 30 pack years, a normal FEV1 of at least 80% of predicted, and a normal FEV1/forced vital capacity (FVC) ratio of at least 70% at enrollment.
Multislice CT scans of the participants’ lungs were performed at baseline to quantify inflation of the lung parenchyma, lung area, and airway dimensions.
Over a mean follow-up of 2.5 years, the participants had an average annual decline in FEV1 of 2.3% of predicted.
Analysis showed that annual declines in FEV1 were significantly associated with baseline percentage of overinflated lung area on CT scans.
Indeed, dividing the participants into quartiles based on increasing percentage of overinflated lung area, at means of 37.1%, 52.6%, 67.0%, and 77.2%, revealed mean annual declines in lung function of 0.9%, 2.0%, 2.3%, and 3.9%, respectively.
Coxson and team conclude: “The present results show a quantitative CT-based estimate of percentage overinflation using individual predicted maximal lung inflation is an independent predictor of rapid decline in lung function in smokers with normal baseline spirometry.”
They add: “These results suggest that, when the FEV1 is normal, a quantitative structural assessment by CT can distinguish the smokers who will develop COPD from those who will not.”
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By Mark Cowen