Paula Lindgren

Bronchodilator response in the lung health study over 11 yrs

Long-term changes in bronchodilator response in people with mild chronic obstructive pulmonary disease were assessed in this study. Changes in forced expiratory volume in one second (FEV1) in response to isoproterenol was measured in 4,194 participants in the Lung Health Study annually for 5 yrs, and again 11 yrs after study entry. Responses were quantitated in terms of mL (absolute), as per cent of the pre-bronchodilator value (relative), and as a per cent of the predicted normal value (% predicted). At baseline, the mean pre-bronchodilator FEV1 was 75.4% predicted, and responses were small. Relative and percentage predicted responses were similar in males and females; and correlated positively with methacholine reactivity, and negatively with smoking intensity and age. Baseline bronchodilator responses did not correlate with subsequent decline in FEV1. There was a substantial increase in response over the first year of the study, largely due to smoking cessation, with larger increases in those who stopped smoking. After the first year absolute responses changed little in those who maintained smoking cessation, but increased in those who did not. Mean relative and percentage predicted responses increased in all participants throughout the study. There was substantial annual variability of absolute response, and it was poorly reproducible in individual participants. In conclusion, smoking cessation increased bronchodilator response, and response did not predict the rate of decline of forced expiratory volume in one second.

Effects of Multiple Attempts to Quit Smoking and Relapses to Smoking on Pulmonary Function

The effect of intermittent smoking on pulmonary function was assessed among participants in the Lung Health Study, 5887 adult smokers with evidence of early chronic obstructive pulmonary disease (COPD), followed up for 5 years. The mean annual rate of loss in FEV1% of predicted after year 1 was smallest for those who quit at some point during the first year of the study and stayed quit (-0.33%/year, +/-0.05%), intermediate for those who smoked intermittently during the study (-0.58%/year, +/-0.05%) and greatest for those who continued to smoke throughout the study (-1.18%/year, +/-0.03%). Surprisingly, those who made several attempts to quit smoking had less loss of lung function at comparable cumulative doses of cigarettes than those who continued to smoke. Quitting smoking for an interval followed by relapse to smoking appeared to provide a measurable and lasting benefit in comparison to continuous smoking. In this early COPD population, not only quitting smoking but attempts to quit smoking can prevent some loss of lung function. These results provide some encouragement to exsmokers who relapse on their way to complete cessation.

Smoking reduction and the rate of decline in FEV1: results from the Lung Health Study

Previous findings from the Lung Health Study have shown that smoking cessation and sustained abstinence substantially reduce the rate of decline in forced expiratory volume (FEV1) among smokers with early chronic obstructive pulmonary disease (COPD) when compared with continuing smoking. Intermittent quitters demonstrated rates of FEV1 decline intermediate between those of sustained quitters and continuing smokers. In this study, data from 1,980 participants were analysed from 10 centres of the Lung Health Study in the USA and Canada. All participants were smokers with mild-to-moderate COPD who were unable to quit smoking at any time during the 1st yr of the study. No linear relationship was found between reduction in cigarettes per day and changes in FEV1 during the 1st yr of the study. However, examination of the data revealed that this relationship was nonlinear. Further analysis found that smokers who reduced their cigarettes per day to very low amounts had smaller declines in FEV1 than those who did not. Reduction in cigarettes per day was associated with only minimal changes in the presence of chronic respiratory symptoms. In conclusion, compensatory changes in smoking behaviour may account for the limited and unpredictable impact of smoking reduction on lung function decline and symptom prevalence when compared with smoking cessation.

Smoking reduction in the Lung Health Study

We examined the ability of smokers who failed to quit smoking in the Lung Health Study to reduce the number of cigarettes per day and maintain this reduction and whether reduction predicted increased or decreased future cessation. In the Lung Health Study, among smokers with early lung disease who wished to stop smoking, 3923 were randomized to a special intervention of counseling and nicotine gum for smoking cessation and to bronchodilator therapy or placebo. Among the 1722 who were still smoking at the first year follow-up, 27% smoked the same, 43% smoked 1%-49% fewer, and 30% smoked at least 50% fewer cigarettes per day. Reduction in cigarettes per day was accompanied by reduction in expired-air carbon monoxide. About half of the less-than-50% reducers and one-fifth of the at-least-50% reducers maintained or exceeded this reduction over the next 4 years. Reduction was associated with nicotine gum use. Greater reduction at year 1 predicted more quit attempts in year 2 but not more point prevalence abstinence at year 2 nor more quits or abstinence between years 2 and 5. We conclude that reduction can be maintained but such reduction neither predicts an increased nor decreased probability of future cessation.

Nicotine gum use in the first year of the lung health study

Of 3,923 special intervention participants in the Lung Health Study who were offered nicotine gum to help them quit smoking, 1,080 (28.9%) were using nicotine gum 12 months after entry into the study. This group is comprised of 33.6% sustained nonsmokers, 54.5% intermittent smokers, and 19.2% continuing smokers. The average use of gum at 12 months is 7.3 pieces per day. At 12 months, men were significantly more likely to be nonsmokers than women, but women were significantly more likely to use gum than men. Among the sustained nonsmokers, continuous gum users reported significantly more mild side effects than those who used gum intermittently, although there were no differences in moderate or severe side effects between the two groups. Overall, the rate of observed side effects was small. Factors associated with nicotine dependence were related to the use and amount of gum use at 12 months.