COPD: Overview of Definitions, Epidemiology, and Factors Influencing Its Development: Observation
This comparison is shown (Fig 1, top right) and demonstrates a steady rate of decline in the continuing smokers. In those who quit, there was an initial improvement in FEV1 followed by a decline at a rate significantly less than that of the continuing smokers and approximating that expected for normal nonsmokers. This substantiates the contention that smoking cessation, in a prospective manner, can decrease the rate of decline of lung function. The effect of ipratropium can be determined by comparing individuals in the smoking cessation group treated with placebo with those treated with ipratropium (Fig 1, bottom left). Ipratropium was associated with a small, but statistically significant, improvement in lung function. After this improvement, however, lung function in the ipratropium group declined at the same rate as that in the placebo group. This improvement in lung function associated with ipratropium therapy persisted as long as the ipratropium therapy was continued. micronase dosage
The observation that progressive loss of lung function can be prevented with smoking cessation suggests a relatively simple approach to the prevention of COPD. Unfortunately, while smoking prevalence rates in the United States declined steadily from nearly 40% in 1965 to nearly 25% in 1990, smoking prevalence has remained essentially unchanged since that time. This is particularly alarming as smoking is now more highly prevalent among younger age groups, suggesting that COPD will continue to remain a common disorder. Consistent with this, it is possible to determine the effectiveness of the smoking cessation intervention used in the Lung Health Study with a so-called “intention to treat” analysis. In this analysis, the “usual care group” is compared with the group of individuals who received the smoking cessation intervention and the placebo treatment (Fig 1, bottom right). While the intervention group did better, this was due to the 22% of people who quit and remained abstinent. As a whole, the difference between the groups was small. This clearly indicates that improved techniques for smoking cessation are absolutely essential.