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30-10-2011 | Radiology | Article

Lung cancer CT screening detects COPD in current, past heavy smokers

Abstract

Free abstract

MedWire News: Individuals with a current or past history of heavy smoking may benefit from undergoing low-dose lung cancer screening computed tomography (CT) scans, suggest study findings showing effective detection of chronic obstructive pulmonary disease (COPD) in this population.

"If CT screening is widely adopted for lung cancer screening, an additional benefit may be early detection of COPD. Early diagnosis is important because smoking cessation early in the COPD disease process slows disease progression and decreases morbidity and mortality," say Onno Mets (University Medical Center Utrecht, the Netherlands) and colleagues.

The researchers performed prebronchodilator pulmonary function testing with inspiratory and expiratory CT on the same day among 1140 men taking part in an ongoing lung cancer screening trial. Pulmonary function tests were used as the reference standard in determining COPD diagnostic accuracy of the CT scans.

Participants were current or former (<10 years) heavy smokers, aged on average 62.5 years, with a smoking history of at least 16 cigarettes per day for 25 years or at least 11 cigarettes per day for 30 years.

Analysis of self-reported respiratory symptom data from 1085 participants showed that 566 reported symptoms, with 3.6% and 8.2% reporting physician-diagnosed emphysema and bronchitis, respectively. Pulmonary lung function testing confirmed that 437 (38%) patients had COPD.

The final diagnostic model for COPD included CT emphysema, CT air trapping, body mass index, pack-years, and smoking status. The optimum cut-off point for accuracy on the receiver operating characteristic (ROC) curve of 0.83 yielded a sensitivity of 63% and a specificity of 88%. Based on this cut-off point, 274 of the 359 positively screened patients were confirmed as having COPD, yielding a positive and negative predictive value of 76% and 79%, respectively.

Further analysis showed that the identified 274 patients comprised 54% (150 of 277) of all patients with mild obstruction, 73% (99 of 135) of all patients with moderate obstruction, and 100% (25 of 25) of all patients with severe obstruction.

Mets and team also note that the diagnostic model showed an area under the ROC curve of 0.87 for patients with symptoms and 0.78 for those without symptoms.

"Our study may add to the debate about whether and how to implement lung cancer screening for heavy smokers because we have shown that detection of COPD using low-dose screening CT scans may be feasible," concludes the team in the Journal of the American Medical Association.

They call for further studies to validate the findings before the model can be implemented in medical practice.

By Ingrid Grasmo

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