Middle-aged men in a Danish study with good cardiorespiratory fitness (CRF) at midlife were less likely to develop chronic obstructive pulmonary disease (COPD) or die from COPD-related causes decades later, according to recent observational study published in the journal Thorax.
“In individuals at risk of developing COPD, fitness enhancing physical activity should be encouraged not only to reduce dyspnea but also to delay development, progression and death from COPD,” Gorm Mørk Hansen, MD, from Herlev-Gentofte University Hospital in Copenhagen, Denmark, and colleagues wrote in their study.
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Dr. Hansen and colleagues analyzed the data from 4,730 middle-aged Danish men recruited between 1970 and 1971 and followed for up to 46 years, evaluating their physical activity, tracking their smoking and alcohol status, and recording their socioeconomic status over time. The mean age for men at the beginning of the study was 48.7 years, and 4,338 men (91.7%) died by the end of the study. Researchers assessed CRF using an ergometer test to determine maximal oxygen uptake capacity, and each patient was categorized as having low, normal or high CRF.
At final follow-up, 626 men (13.2%) had COPD and 223 men (4.9%) had died from COPD-related complications as reported in a national registry. Men with normal CRF had a 21% lowered risk of developing COPD compared with men who had low CRF (hazard ratio, 0.79; 95% confidence interval, 0.63-0.99), while men with high CRF had a 31% lower risk compared with men with low CRF (HR, 0.69, 95% CI, 0.52-0.91). Mortality risk for men with normal CRF was 35% lower than men with low CRF (HR, 0.65, 95% CI, 0.46-0.91), and men who had high CRF had a 62% lower mortality risk compared with men who had lower CRF (HR, 0.38, 95% CI, 0.23-0.61).
When analyzing restricted mean survival times and compared with low CRF, normal CRF levels were associated with a delay in COPD diagnosis of 1.79 years (95% CI, 0.14-3.45; P = .034), while high CRF levels were associated with a delay of 1.45 years (95% CI, −0.71–3.60; P = .19). In men with normal and CRF, death from COPD-related causes was delayed by 1.28 years (95% CI, 0.04-2.52; P = .042) and 1.8 years (95% CI, 0.19-3.42; P = .028), respectively, compared with men with low CRF.
Although the relationship between CRF and COPD are still unknown and the results do not show causality due to the observational nature of the study, there appears to be a link between the two, the researchers said.
“[I]t is possible that participants with high levels of CRF were more resilient to and less symptomatic of underlying COPD, and therefore had a delayed healthcare contact,” the authors said. “But since death from COPD is also reduced with increasing levels of CRF, it is unlikely that delayed time to diagnosis can explain our results entirely.”