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Thorax. 2019 Jun 17. pii: thoraxjnl-2018-212821. doi: 10.1136/thoraxjnl-2018-212821. [Epub ahead of print]

Midlife cardiorespiratory fitness and the long-term risk of chronic obstructive pulmonary disease.

Author information

1
Herlev-Gentofte University Hospital, Medical Department O, Respiratory Section; Herlev-Gentofte University Hospital, Department of Cardiology, Copenhagen, Denmark gormmh@gmail.com.
2
The Copenhagen Male Study Epidemiological Research Unit, Departments of Occupational and Environmental Medicine, Bispebjerg University Hospital; The Copenhagen City Heart Study, Frederiksberg Hospital, Copenhagen, Denmark.
3
National Research Centre for the Working Environment; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Copenhagen, Denmark.
4
The Copenhagen Male Study Epidemiological Research Unit, Departments of Occupational and Environmental Medicine, Bispebjerg University Hospital; Bispebjerg Hospital, National Research Centre for the Working Environment, Copenhagen, Denmark.
5
Herlev Hospital, Medical Department O, Respiratory Section; University of Copenhagen, Section of Epidemiology, Department of Public Health, Copenhagen, Denmark.
6
The Copenhagen Male Study Epidemiological Research Unit, Departments of Occupational and Environmental Medicine, Bispebjerg University Hospital, Copenhagen, Denmark, Copenhagen, Denmark.
7
Department of Cardiology, Rigshospitalet University Hospital, Copenhagen, Denmark.

Abstract

BACKGROUND:

Good midlife cardiorespiratory fitness (CRF) may reduce the risk of chronic obstructive pulmonary disease (COPD). Reverse causation may play a role if follow-up time is short. We examined the association between CRF and both incident COPD and COPD mortality in employed men with up to 46 years follow-up, which allowed us to account for reverse causality.

METHODS:

Middle-aged men (n=4730) were recruited in 1970-1971. CRF was determined as VO2max by ergometer test. Categories of CRF (low, normal, high) were defined as ± 1 Z-score (± 1 SD) above or below the age-adjusted mean. Endpoints were identified through national registers and defined as incident COPD, and death from COPD. Multi-adjusted Cox models and restricted mean survival times (RMST) were performed.

RESULTS:

Compared with low CRF, the estimated risk of incident COPD was 21% lower in participants with normal CRF (HR 0.79, 95% CI 0.63 to 0.99) and 31 % lower with high CRF (HR 0.69, 95% CI 0.52 to 0.91). Compared with low CRF, the risk of death from COPD was 35% lower in participants with normal CRF (HR 0.65, 95% CI 0.46 to 0.91) and 62% lower in participants with high CRF (HR 0.38, 95% CI 0.23 to 0.61). RMST showed a delay to incident COPD and death from COPD in the magnitude of 1.3-1.8 years in normal and high CRF vs low CRF. Test for reverse causation did not alter the results.

CONCLUSION:

In a population of healthy, middle-aged men, higher levels of CRF were associated with a lower long-term risk of incident COPD and death from COPD.

KEYWORDS:

copd epidemiology; exercise

Conflict of interest statement

Competing interests: None declared.

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