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Centrilobular emphysema (CLE) and paraseptal emphysema (PSE) are observed in smokers with preserved ratio impaired spirometry (PRISm, defined as the ratio of forced expiratory volume in 1 s (FEV 1 ) to forced vital capacity (FVC) ≥0.7 and FEV 1 <80%), but their prevalence and physiological impacts remain unestablished. This multicentre study aimed to investigate its prevalence and to test whether emphysema subtypes are differently associated with physiological impairments in smokers with PRISm. Both never- and ever-smokers aged ≥40 years who underwent computed tomography (CT) for lung cancer screening and spirometry were retrospectively and consecutively enrolled at three hospitals and a clinic. Emphysema subtypes were visually classified according to the Fleischner system. Air-trapping was assessed as the ratio of FVC to total lung capacity on CT (TLC CT ). In 1046 never-smokers and 772 smokers with ≥10 pack-years, the prevalence of PRISm was 8.2% and 11.3%, respectively. The prevalence of PSE and CLE in smokers with PRISm was comparable to that in smokers with normal spirometry (PSE 43.7% versus 36.2%, p=1.00; CLE 46.0% versus 31.8%, p=0.21), but higher than that in never-smokers with PRISm (PSE 43.7% versus 1.2%, p<0.01; CLE 46% versus 4.7%, p<0.01) and lower than that in smokers with airflow limitation (PSE 43.7% versus 71.0%, p<0.01; CLE 46% versus 79.3%, p<0.01). The presence of CLE, but not PSE, was independently associated with reduced FVC/TLC CT in smokers with PRISm. Both PSE and CLE were common, but only CLE was associated with air-trapping in smokers with PRISm, suggesting different physiological roles of these emphysema subtypes., Competing Interests: Conflicts of interest: N. Tanabe, S. Sato, T. Oguma and T. Hirai were supported by a grant from FUJIFILM Co., Ltd. FUJIFILM did not have a role in the design or analysis of the study or in the writing of the manuscript. The other authors have no conflict of interest to declare., (Copyright ©The authors 2022.)

This study assessed the sensory and emotional aspects of breathlessness under the same exercise load in patients with COPD. Breathing discomfort with constant exercise predicted exacerbations within 1 year. https://bit.ly/3l2oA4A., Competing Interests: Conflict of interest: M. Kanezaki has nothing to disclose. Conflict of interest: K. Terada has no financial conflicts of interest to disclose concerning the submitted work. Conflict of interest: N. Tanabe reports grants from FUJIFILM Co., Ltd outside the submitted work. Conflict of interest: H. Shima has nothing to disclose. Conflict of interest: Y. Hamakawa has nothing to disclose. Conflict of interest: S. Sato reports grants from Boehringer Ingelheim Co., Ltd, and FUJIFILM Co., Ltd, outside the submitted work., (Copyright ©The authors 2021.)

The concept that the small airway is a primary pathological site for all COPD phenotypes has been challenged by recent findings that the disease starts from the central airways in COPD subgroups and that a smaller central airway tree increases COPD risk. This study aimed to examine whether the computed tomography (CT)-based airway disease-dominant (AD) subtype, defined using the central airway dimension, was less associated with small airway dysfunction (SAD) on CT, compared to the emphysema-dominant (ED) subtype . COPD patients were categorised into mild, AD, ED and mixed groups based on wall area per cent (WA%) of the segmental airways and low attenuation volume per cent in the Kyoto-Himeji (n=189) and Hokkaido COPD cohorts (n=93). The volume per cent of SAD regions (SAD%) was obtained by nonrigidly registering inspiratory and expiratory CT. The AD group had a lower SAD% than the ED group and similar SAD% to the mild group. The AD group had a smaller lumen size of airways proximal to the segmental airways and more frequent asthma history before age 40 years than the ED group. In multivariable analyses, while the AD and ED groups were similarly associated with greater airflow limitation, the ED, but not the AD, group was associated with greater SAD%, whereas the AD, but not the ED, group was associated with a smaller central airway size. The CT-based AD COPD subtype might be associated with a smaller central airway tree and asthma history, but not with peripheral lung pathologies including small airway disease, unlike the ED subtype., Competing Interests: Conflict of interest: N. Tanabe reports grants from FUJIFILM during the conduct of the study; and personal fees from AstraZeneca, Nippon Boehringer Ingelheim and GlaxoSmithKline outside the submitted work. Conflict of interest: K. Shimizu has nothing to disclose. Conflict of interest: K. Terada has nothing to disclose. Conflict of interest: S. Sato has nothing to disclose. Conflict of interest: M. Suzuki reports grants and lecture fees from AstraZeneca and Novartis, and lecture fees from Boehringer Ingelheim and GlaxoSmithKline, outside the submitted work. Conflict of interest: H. Shima has nothing to disclose. Conflict of interest: A. Oguma has nothing to disclose. Conflict of interest: T. Oguma reports joint research with FUJIFILM during the conduct of the study, and lecture fees from AstraZeneca, Boehringer Ingelheim and GlaxoSmithKline outside the submitted work. Conflict of interest: S. Konno reports grants from AstraZeneca, Novartis, Boehringer Ingelheim and Kyorin outside the submitted work. Conflict of interest: M. Nishimura reports grants from Nippon Boehringer Ingelheim and Pfizer Japan during the conduct of the study. Conflict of interest: T. Hirai reports grants from FUJIFILM during the conduct of the study., (Copyright ©The authors 2021.)