COPD: Smoking, Emphysema Speed Lung Function Loss

In addition, "defining GOLD stage 1 disease as a ratio of FEV₁ to forced vital capacity (FVC) of less than 0.7, applied to all age groups, may lead to overreporting of abnormal ratios in older age groups and underreporting of them in younger age groups," said Dr. Burney of the National Heart and Lung Institute, Imperial College, London.

"Failure to distinguish between FEV₁ as a sign of obstruction and FEV₁ as a marker of low FVC has caused much confusion, mostly due to failure to measure or report FVC. It is almost certainly responsible for the association between ventilator function and markers of systemic inflammation in the cross-sectional data for ECLIPSE and has similarly led to inflated associations of ‘obstruction’ with increased all-cause mortality and cardiovascular events in so-called normal populations," Dr. Burney wrote.

As with other studies, he continued, this one showed that those who quit smoking have no clear loss of lung function over time, compared with nonsmokers, adding to the body of evidence that quitting smoking can reduce the rate of decline of lung function. The important message from ECLIPSE is that it is never too late to derive benefit from quitting smoking, although patients derive more benefits by doing so earlier, he noted.

The study was supported by grants from GlaxoSmithKline to Dr. Vestbo and several coauthors. Some of the coauthors are employees of and own stock in GlaxoSmithKline. All coauthors reported ties to numerous pharmaceutical companies, including AstraZeneca, Boehringer Ingelheim, Novartis, and Pfizer.

Dr. Burney disclosed receiving consulting fees from GlaxoSmithKline and lecture fees from Pfizer and Boehringer Ingelheim.