Both former and current smokers have accelerated lung function decline compared with never-smokers, according to study results published in The Lancet Respiratory Medicine.

Lung function values over time measured by spirometry were compared between cohorts of adults categorized by age. Cohorts consisted of younger adults (≥17 years), middle-aged and older adults (≥45 years), and elderly adults (≥65 years). The decline in forced expiratory volume in 1 second (FEV1) in sustained former smokers and current smokers was compared with that of never-smokers within each age group.

The median age of the 25,352 patients was 57 years. FEV1 decline at the median age was 31.01 mL per year in sustained never-smokers, 34.97 mL per year in former smokers, and 39.92 mL per year in current smokers. Former smokers showed an adjusted accelerated FEV1 decline of 1.82 mL per year compared with never-smokers, which was approximately 20% of the effect estimate for current smokers. FEV1 decline was observed in former smokers for decades after smoking cessation compared with never smokers.

Study limitations included self-reporting smoking status, misclassification of former smokers as never smokers and vice-versa, and misclassification of current smokers as former smokers and of high-intensity vs low-intensity smokers.

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These findings reinforce the US Surgeon General’s position that there is no safe level of tobacco smoke exposure and that smoking cessation is the most effective means of harm reduction,” the researchers wrote.

Reference

Oelsner EC, Balte PP, Bhatt SP, et al. Lung function decline in former smokers and low-intensity current smokers: a secondary data analysis of the NHLBI Pooled Cohorts Study [published October 9th, 2019]. J Infect Dis. doi:10.1016/S2213-2600(19)30276-0