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.