Increased mortality in patients with severe COPD associated with high-intensity exercise: a preliminary cohort study
Authors Schaadt L, Christensen R, Kristensen LE, Henriksen M
Received 13 June 2016
Accepted for publication 19 August 2016
Published 26 September 2016 Volume 2016:11(1) Pages 2329—2334
Checked for plagiarism Yes
Review by Single-blind
Peer reviewer comments 3
Editor who approved publication: Dr Richard Russell
Lone Schaadt,1,2 Robin Christensen,2 Lars Erik Kristensen,2 Marius Henriksen1,2
1Department of Physio- and Occupational Therapy, 2The Parker Institute, Copenhagen University Hospital Bispebjerg-Frederiksberg, Copenhagen, Denmark
Introduction: Intensity of exercise is believed to be a key determinant of response to chronic obstructive pulmonary disease (COPD) rehabilitation. We hypothesized that a higher intensity of exercise, in combination with physiotherapist-led instructions and education in management of breathlessness, would lead to better self-management, possibly delaying calls to the emergency service and preventing hospitalization.
Objective: We aimed to test this hypothesis in a subsequent randomized trial, and in order to test study processes and estimate hospitalization rates, we did a small preliminary prospective cohort study on severe COPD patients referred to outpatient rehabilitation.
Methods: In 2013, four rehabilitation courses were scheduled (spring, summer, autumn, and winter) each lasting 8 weeks and including eight to ten patients. This preliminary study was designed as a controlled cohort study. The bi-weekly exercise sessions in the spring and autumn courses included a high-intensity walking exercise at 95% of estimated VO2 max for as long as possible. The other two rehabilitation courses included the usual walking exercise intensity (85% of estimated VO2 max). Hospitalization rates were assessed from the participants’ medical records in an 18-month period.
Results: We were able to enroll 31 patients in total (15 in the high-intensity exercise group and 16 in regular intensity). There were no group differences in the hospitalization rates. However, during review of the medical records, we observed a striking mortality rate among participants who had attended the high-intensity rehabilitation courses (five deaths) compared to the standard rehabilitation (zero deaths). Four of the five deaths were COPD exacerbations. Fisher’s exact test was statistically significant (P=0.046), as was a log-rank test (P=0.019) of the Kaplan–Meier estimated survival rates.
Conclusion: These results from this small preliminary cohort study are alarming and raise concerns about the possible serious risks associated with high-intensity exercise rehabilitation of severe COPD patients.
Keywords: Chronic obstructive pulmonary disease, exercise, rehabilitation, mortality
This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.Download Article [PDF] View Full Text [HTML][Machine readable]