At least one in four hardened smokers will develop progressive lung disease

Newswise — At least one in four hardened smokers will develop the progressive and incurable lung disease COPD, finds a long term study published ahead of print in Thorax.

This is a higher risk than previously thought, say the researchers.

COPD, or chronic obstructive pulmonary disease, is an umbrella term for respiratory diseases, including bronchitis and emphysema, which block air flow through the lungs, and which worsen over time.

The researchers base their findings on 8,000 men and women aged between 30 and 60, who were monitored for 25 years as part of the Copenhagen City Heart Study. More than 5,000 people were smokers and just over 1200 were ex smokers.

At the start of the study their lungs were working normally and they had no respiratory problems. Their lung health was checked regularly throughout the monitoring period.

The lungs of almost all the male non-smokers continued to work well, but this was only true for 6 out of 10 of those who continued to smoke throughout the monitoring period.

Similarly, 9 out of 10 female non-smokers still had healthy lungs at the end of the monitoring period, but this was only true of 7 out of 10 of the smokers.

One in four people developed severe or moderate COPD over the 25 years. The highest rates were seen in persistent smokers.

They were six times more likely to develop COPD than non smokers. And one in four of them developed stage 2 or higher COPD: there are four stages.

Of the 2,900 deaths recorded over the 25 years, 109 were directly attributable to COPD. Virtually all the deaths were in people who had been active smokers at the start of the study. Only two non-smokers died of the disease.

The risk of COPD plummeted among those who gave up smoking soon after the study started, which accounts for the fact that none of the ex-smokers developed severe COPD and that only seven of them died, say the authors.

Because life expectancy is increasing in affluent nations, and death rates from heart disease are falling, rates of COPD will remain high “for many years to come,” despite the decline in the numbers of people smoking, they add.