Sex differences in emphysema phenotype in smokers without airflow obstruction

Data on sex differences in emphysema are limited to chronic obstructive pulmonary disease. We aimed to verify whether such differences also exist in smokers without airflow obstruction, weighting their influence on the relationship between emphysema and clinical features. We evaluated both clinical and multidetector computed tomography (MDCT) data of 1,011 heavy smokers recruited by a lung cancer screening project. MDCT scans were analysed with software allowing lobar quantification of emphysema features. For these measures, multiple regression models were applied to assess the effect of patients sex, after allowance for age, body mass index (BMI), smoking history, forced expiratory volume in 1 s (FEV1) and forced vital capacity. The final study cohort consisted of 957 smokers without airflow obstruction. Compared with males, females exhibited an emphysema phenotype less extensive in each pulmonary lobe, characterised by smaller emphysematous areas and less concentrated in the core of the lung. However, in females, the increase of emphysema with age was more pronounced and displayed a more significant relationship with FEV1% decline; conversely, in males there was a stronger association with the decrease in BMI. Males and females respond differently to the type and location of lung damage due to tobacco exposure. In smokers, sex influences the relationship between emphysema and clinical features.