KEY POINTS:
Lung damage in smokers continues to worsen even after they have quit, new research shows.
The study, conducted by an international team of researchers in respiratory medicine including Massey University's Dr Felix Ram, shatters the conventional medical wisdom that smokers with lung disease should stop smoking to halt further damage.
Instead, it shows that once smokers have established lung disease with bronchial inflammation, the problem will just continue even after they have given up the habit.
"The study has wide implications for how we manage patients with smoking-related lung disease and for all smokers at large," said Dr Ram, a senior lecturer in clinical pharmacology at Massey's Albany campus.
"Instead of telling smokers that it's never too late to quit, the new public health message is never take up smoking," he said.
The study was conducted with bronchial biopsy samples from 101 patients in British hospitals.
All had been diagnosed with chronic obstructive pulmonary disease, a long-term lung condition usually caused by smoking. It often brings with it chronic bronchial inflammation, and symptoms include coughing and shortness of breath.
Patients often describe the condition as similar to breathing through a straw.
Of the subjects, 65 were smokers and 36 former smokers. All were aged between 60 and 65 and had a-pack-a-day habits. Those who had given up had stopped about eight years earlier.
Dr Ram said analysis of inflammatory cell types and markers found no statistically significant difference between the smokers and ex-smokers.
"We have conclusively shown that if you have stopped smoking once you have lung disease, the problem will not leave you. It will continue to decline the same as it would if you continued to smoke."
It was still unknown how much or how long someone needed to smoke before lung disease set in.
"How much does one need to smoke in order to have the beginnings of lung damage? I guess that's an unknown at this stage."
He cautions against smokers taking the results as a reason not to quit.
"This doesn't mean that there is no point in quitting smoking," said Dr Ram. "Lung inflammatory damage will continue but smoking has other health effects and smokers will still benefit from giving up."
Dr Ram, now based at Massey's School of Health Sciences at Albany, has an ongoing research relationship with leading respiratory medicine researchers in Europe.
The research was published in the European Respiratory Journal.
