Systematic review of the evidence relating FEV1decline to giving up smoking

Abstract

BackgroundThe rate of forced expiratory volume in 1 second (FEV1) decline ("beta") is a marker of chronic obstructive pulmonary disease risk. The reduction in beta after quitting smoking is an upper limit for the reduction achievable from switching to novel nicotine delivery products. We review available evidence to estimate this reduction and quantify the relationship of smoking to beta.MethodsStudies were identified, in healthy individuals or patients with respiratory disease, that provided data on beta over at least 2 years of follow-up, separately for those who gave up smoking and other smoking groups. Publications to June 2010 were considered. Independent beta estimates were derived for four main smoking groups: never smokers, ex-smokers (before baseline), quitters (during follow-up) and continuing smokers. Unweighted and inverse variance-weighted regression analyses compared betas in the smoking groups, and in continuing smokers by amount smoked, and estimated whether beta or beta differences between smoking groups varied by age, sex and other factors.ResultsForty-seven studies had relevant data, 28 for both sexes and 19 for males. Sixteen studies started before 1970. Mean follow-up was 11 years. On the basis of weighted analysis of 303 betas for the four smoking groups, never smokers had a beta 10.8 mL/yr (95% confidence interval (CI), 8.9 to 12.8) less than continuing smokers. Betas for ex-smokers were 12.4 mL/yr (95% CI, 10.1 to 14.7) less than for continuing smokers, and for quitters, 8.5 mL/yr (95% CI, 5.6 to 11.4) less. These betas were similar to that for never smokers. In continuing smokers, beta increased 0.33 mL/yr per cigarette/day. Beta differences between continuing smokers and those who gave up were greater in patients with respiratory disease or with reduced baseline lung function, but were not clearly related to age or sex.ConclusionThe available data have numerous limitations, but clearly show that continuing smokers have a beta that is dose-related and over 10 mL/yr greater than in never smokers, ex-smokers or quitters. The greater decline in those with respiratory disease or reduced lung function is consistent with some smokers having a more rapid rate of FEV1 decline. These results help in designing studies comparing continuing smokers of conventional cigarettes and switchers to novel products.

Pulmonary involvement in Fabry disease: Overview and perspectives

“…An association with smoking in this regard was not investigated. This impairment is clearly pathological when compared to the findings of a recent, detailed systematic review of 47 studies in healthy individuals or patients with respiratory disease performed by Lee et al These authors measured a FEV1 decline in active smokers of over 40 ml per year compared to less than 30 ml year in never smokers [32]. Notably, the FEV1 decline in Fabry patients, irrespective of their smoking status, 8 8 appears to be of the same order of magnitude of active smokers not affected with FD.…”

Chronic Obstructive Pulmonary Disease: Official diagnosis and treatment guidelines of the Czech Pneumological and Phthisiological Society; a novel phenotypic approach to COPD with patient-oriented care

“…In contrast, it has been clearly demonstrated that continuing exposure to smoke considerably accelerates disease progression, independently of its initial stage 12,57 . The effect of reduction of other risk factors has not been studied in detail; however, it is expected to be associated with a positive impact on the patient.…”

“…Elimination of risks (1 st step): Smoking cessation significantly decelerates the declination in lung function 4,5,56,57 . In contrast, it has been clearly demonstrated that continuing exposure to smoke considerably accelerates disease progression, independently of its initial stage 12,57 .…”

ExperimentalPneumocystislung infection promotes M2a alveolar macrophage-derived MMP12 production

“…2). These components in turn contribute to chronic cough and sputum production that ultimately leads to a decrease in the forced expiratory volume in 1 s (FEV 1 ) compared with predicted FEV 1 (18).…”