Lower respiratory illnesses promote FEV1 decline in current smokers but not ex-smokers with mild chronic obstructive pulmonary disease - Results fromthe Lung Health Study

We analyzed Lung Health Study (LHS) data to assess the effect of self-repor ted lower respiratory illnesses resulting in physician visits (LRI) on lung function. Participants were 5,887 smokers aged 35-60 yr, FEV1/FVC < 0.70 a nd FEV1 of 55-90% predicted. Two-thirds were randomized into an intensive s moking cessation program (SI); one-third were advised only to stop smoking (UC). For 5 yr participants had annual spirometry and questioning regarding LRI. SI had greater rates of smoking cessation than usual care (UC) with f ewer LRI (p = 0.0008). Sustained quitters had fewer LRI than continuing smo kers (p = 0.0003). In the year LRI occurred, FEV1 did not change in sustain ed quitters, but decreased significantly in smokers (p = 0.0001) with some recovery the following year if no LRI occurred. Over 5 yr, LRI had a signif icant effect on rate of decline of FEV1 only in smokers. In smokers averagi ng one LRI/yr over 5 yr there were additional declines in FEV1 of 7 ml/yr ( p = 0.001). Smokers with more than one LRI/yr had greater declines. Chronic bronchitis was associated with increased frequencies of LRI, but did not a ffect their influence on lung function. Smoking and LRI had an interactive effect on FEV1, in people with mild COPD, and in smokers frequent LRI may i nfluence the longterm course of the disease.