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ABSTRACT: 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.
European Respiratory Journal 08/2005; 26(1):45-51. · 5.89 Impact Factor
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ABSTRACT: 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 (FEV(1)) among smokers with early chronic obstructive pulmonary disease (COPD) when compared with continuing smoking. Intermittent quitters demonstrated rates of FEV(1) 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 FEV(1) 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 FEV(1) 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.
European Respiratory Journal 07/2005; 25(6):1011-7. · 5.89 Impact Factor
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ABSTRACT: This study describes baseline and Year 1 predictors of abstinence from smoking for the 3,523 intervention participants who had complete annual 5-year follow-up data in the Lung Health Study (LHS).
The LHS enrolled 5,887 smokers, aged 35 to 60 years, of whom 3,923 were offered a cessation intervention. Of these, 22% achieved biochemically verified abstinence for 5 years. Logistic regressions were performed. The first outcome variable was abstinence from smoking at 1 year. Then for those who were quit at 1 year, the outcome variable was 5 years of sustained abstinence.
All participants who were not using nicotine gum after 1 year in the study were more likely to sustain cessation over 5 years than were gum users at year 1 (OR ranged from 0.31 to 0.44 for four age- and sex-specific groups). Baseline number of previous quit attempts was negatively associated with 5-year quitting success among younger and older men (OR = 0.82 and 0.83). Older participants who were less likely to associate smoking with emotional coping had higher abstinence rates at 5 years of follow-up (OR = 0.89 and 0.84).
Different mechanisms may be responsible for achieving cessation in age/gender groups. These results have implications for planning successful interventions.
Preventive Medicine 06/2000; 30(5):392-400. · 3.22 Impact Factor
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ABSTRACT: 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.
Journal of Clinical Epidemiology 01/1999; 51(12):1317-26. · 4.27 Impact Factor
