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Original Research: COPD |

Influence of Season on Exacerbation Characteristics in Patients With COPDCOPD Exacerbation Seasonality

Gavin C. Donaldson, PhD; James J. Goldring, MBBS; Jadwiga A. Wedzicha, MD
Author and Funding Information

From the Academic Unit of Respiratory Medicine, UCL Medical School, Royal Free Campus, London, England.

Correspondence to: Gavin C. Donaldson, PhD, Academic Unit of Respiratory Medicine, UCL Medical School, Royal Free Campus, Rowland Hill St, Hampstead, London, NW3 2PF, England; e-mail: g.donaldson@ucl.ac.uk


Funding/Support: The London COPD cohort is funded by the Medical Research Council, United Kingdom [Grant MRC G0800570].

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).


© 2012 American College of Chest Physicians


Chest. 2012;141(1):94-100. doi:10.1378/chest.11-0281
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Background:  Patients with COPD experience more frequent exacerbations in the winter. However, little is known about the impact of the seasons on exacerbation characteristics.

Methods:  Between November 1, 1995, and November 1, 2009, 307 patients in the London COPD cohort (196 men; age, mean, 68.1 years [SD, 8.4]; FEV1, mean, 1.12 L [SD, 0.46]; FEV1, mean, % predicted, 44.4% [SD, 16.1]) recorded their increase in daily symptoms and time outdoors for a median of 1,021 days (interquartile range [IQR], 631-1,576). Exacerbation was identified as ≥ 2 consecutive days with an increase in two different symptoms.

Results:  There were 1,052 exacerbations in the cold seasons (November to February), of which 42.5% and 50.6% were patients who had coryzal and cough symptoms, respectively, compared with 676 exacerbations in the warm seasons (May to August), of which 31.4% and 45.4% were in patients who had coryzal and cough symptoms, respectively (P < .05). The exacerbation recovery period was longer in the cold seasons (10 days; IQR, 6-19) compared with the warm seasons (9 days; IQR, 5-16; P < .005). The decrease in outdoor activity during exacerbation, relative to a pre-exacerbation period (−14 to −8 days), was greater in the cold seasons (−0.50 h/d; IQR, −1.1 to 0) than in the warm seasons (−0.26 h/d; IQR, −0.88 to 0.18; P = .048). In the cold seasons, 8.4% of exacerbations resulted in patients who were hospitalized, compared with 4.6% of exacerbations in the warm seasons (P = .005).

Conclusions:  Exacerbations are more severe between November and February. This contributes to the increased morbidity during the winter seasons.

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