title: COPD prognosis in relation to diagnostic criteria for airflow obstruction in smokers.
abstract: The aim of this study was to establish which cut-off point for the forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio (i.e. fixed 0.70 or lower limit of normal (LLN) cut-off point) best predicts accelerated lung function decline and exacerbations in middle-aged smokers. We performed secondary analyses on the Lung Health Study dataset. 4045 smokers aged 35-60 years with mild-to-moderate obstructive pulmonary disease were subdivided into categories based on presence or absence of obstruction according to both FEV1/FVC cut-off points. Post-bronchodilator FEV1 decline served as the primary outcome to compare subjects between the categories. 583 (14.4%) subjects were nonobstructed and 3230 (79.8%) subjects were obstructed according to both FEV1/FVC cut-off points. 173 (4.3%) subjects were obstructed according to the fixed cut-off point, but not according to the LLN cut-off point ("discordant" subjects). Mean±SE post-bronchodilator FEV1 decline was 41.8±2.0 mL·year(-1) in nonobstructed subjects, 43.8±3.8 mL·year(-1) in discordant subjects and 53.5±0.9 mL·year(-1) in obstructed subjects (p<0.001). Our study showed that FEV1 decline in subjects deemed obstructed according to a fixed criterion (FEV1/FVC <0.70), but non-obstructed by a sex- and age-specific criterion (LLN) closely resembles FEV1 decline in subjects designated as non-obstructed by both criteria. Sex and age should be taken into account when assessing airflow obstruction in middle-aged smokers.
authors.affiliation: Radboud university medical center, Nijmegen.
authors.forename: Reinier P
authors.initials: RP
authors.lastname: Akkermans
authors.forename: Marion
authors.initials: M
authors.lastname: Biermans
authors.forename: Bas
authors.initials: B
authors.lastname: Robberts
authors.forename: Gerben
authors.initials: G
authors.lastname: ter Riet
authors.forename: Annelies
authors.initials: A
authors.lastname: Jacobs
authors.forename: Chris
authors.initials: C
authors.lastname: van Weel
authors.forename: Michel
authors.initials: M
authors.lastname: Wensing
authors.forename: Tjard
authors.initials: T
authors.lastname: Schermer
mesh_terms: D000328:Adult; D000402:Airway Obstruction / Q000175:diagnosis* / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D012720:Severity of Illness Index; D012907:Smoking; D014797:Vital Capacity