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Chest. 2012 Jan;141(1):94-100. doi: 10.1378/chest.11-0281. Epub 2011 Jul 28.

Influence of season on exacerbation characteristics in patients with COPD.

Author information

1
Academic Unit of Respiratory Medicine, UCL Medical School, Royal Free Campus, London, England. Electronic address: g.donaldson@ucl.ac.uk.
2
Academic Unit of Respiratory Medicine, UCL Medical School, Royal Free Campus, London, England.

Abstract

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]; FEV(1), mean, 1.12 L [SD, 0.46]; FEV(1), 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.

PMID:
21799024
DOI:
10.1378/chest.11-0281
[Indexed for MEDLINE]

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