Airflow limitation classified with the fixed ratio or the lower limit of normal and cause-specific mortality - A prospective study

Kjell Torén; Martin Andersson; Anna-Carin Olin; Paul D Blanc; Bengt Järvholm

doi:10.1016/j.rmed.2018.10.001

Airflow limitation classified with the fixed ratio or the lower limit of normal and cause-specific mortality - A prospective study

Respir Med. 2018 Nov:144:36-41. doi: 10.1016/j.rmed.2018.10.001. Epub 2018 Oct 4.

Authors

Kjell Torén¹, Martin Andersson², Anna-Carin Olin³, Paul D Blanc⁴, Bengt Järvholm²

Affiliations

¹ Section of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, Box 414, SE-405 30, Gothenburg, Sweden; Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital, Box 414, SE-405 30, Gothenburg, Sweden. Electronic address: Kjell.Toren@amm.gu.se.
² Department of Occupational and Environmental Medicine, Institute of Clinical Medicine and Public Health, University of Umeå, SE-901 87, Umeå, Sweden.
³ Section of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, Box 414, SE-405 30, Gothenburg, Sweden; Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital, Box 414, SE-405 30, Gothenburg, Sweden.
⁴ Division of Occupational and Environmental Medicine, Department of Medicine, University of California, PO 0924, San Francisco, CA, USA.

PMID: 30366582
DOI: 10.1016/j.rmed.2018.10.001

Abstract

Background: There is controversy as to whether airflow limitation should be defined as forced expiratory volume in 1 s (FEV₁)/vital capacity (VC) < 0.7 or as FEV₁/VC< the lower limit of normal (LLN). The aim was to examine whether different definitions of airflow limitation differ in predicting mortality.

Methods: Longitudinal prospective study of a national cohort of Swedish workers (199,408 men; 7988 women), aged 20-64 years with spirometry without bronchodilation at baseline followed from 1979 until death, or censorship at 2010. Airflow limitation (AL) by Global Obstructive Lung Disease criteria, AL_GOLD, was defined as FEV₁/VC < 0.7; AL_LLN as FEV₁/VC < LLN. All all-cause, COPD and cardiovascular disease mortality was analyzed among men and women in relation to AL_GOLD and AL_LLN, adjusted for age and smoking.

Results: Among men, all-cause mortality risks were similar by airflow limitation criteria: AL_GOLD RR = 1.32, 95% CI 1.26-1.38; AL_LLN, RR = 1.37, 95% CI 1.31-1.44. The risk estimates were also similar by airflow limitation definition for cardiovascular mortality and for COPD mortality. Among women, all-cause mortality was also similar by airflow limitation criteria, but significantly higher as compared to men: AL_GOLD RR = 2.10, 95% CI 1.66-2.66; AL_LLN, RR = 2.09, 95% CI 1.66-2.62. Also cardiovascular and COPD mortality by airflow limitation criteria was significantly higher among women as compared to men.

Conclusions: Defined either as FEV₁/VC < 0.7 or as FEV₁/VC < LLN, airflow limitation predicted excess mortality risk of similar magnitude. Mortality in relation to airflow limitation was higher among women compared to men.

Keywords: COPD; Epidemiology; GOLD; Never smokers; Spirometry; Women.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Age Factors
Cardiovascular Diseases / mortality*
Cardiovascular Diseases / physiopathology*
Cause of Death
Cohort Studies
Construction Industry
Female
Forced Expiratory Volume
Humans
Longitudinal Studies
Male
Middle Aged
Occupational Health
Prospective Studies
Pulmonary Disease, Chronic Obstructive / mortality*
Pulmonary Disease, Chronic Obstructive / physiopathology*
Pulmonary Ventilation*
Sex Factors
Smoking
Spirometry
Vital Capacity
Young Adult