COPD Exacerbations Twice as Common in Winter

October 2011


Elsevier Global Medical News


DENVER - Exacerbations and deaths among patients with chronic obstructive pulmonary disease follow a pronounced pattern of seasonal variation, according to an analysis of data from a randomized, controlled trial.

The rate of exacerbations requiring treatment was about twice as high during the winter as during the summer, according to the analysis of data from the Prevention of Exacerbations With Tiotropium (POET) in COPD trial, which enrolled 7,376 patients with moderate to very severe COPD.

The rate of death from any cause followed a similar pattern, with about twice the rate of all-cause deaths occurring in the winter. In all, 142 of the patients died from any cause during the trial, said Dr. Thomas Glaab, head of respiratory medicine at Boehringer Ingelheim.

The randomized, double-blind trial enrolled patients from 25 countries and assigned them to treatment with tiotropium, manufactured by Boehringer Ingelheim, or salmeterol. Main results have been previously reported (N. Engl. J. Med. 2011;364:1093-103).

The participating patients had a mean age of 63 years, and 48% were current smokers. Most had stage II (49%) or stage III (43%) disease, according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. On average, their forced expiratory volume in 1 second (FEV1) was 49% of that predicted.

During the 1-year trial, the patients had a total of 4,411 exacerbations that were moderate (defined as requiring treatment with systemic corticosteroids and/or antibiotics) or severe (requiring hospitalization).

Results showed that such exacerbations were twice as common during the winter versus summer months. Specifically, there were nearly 500 monthly exacerbations between December and February, compared with about 250 monthly exacerbations between June and August, Dr. Glaab reported at an international conference of the American Thoracic Society.

On an individual basis, the mean rate was 0.073-0.081 exacerbations per patient per month during the winter months, compared with 0.033-0.037 during the summer months, regardless of treatment group.

The pattern was stronger for exacerbations treated with antibiotics - likely reflecting the role of respiratory infections - than for exacerbations treated with steroids, Dr. Glaab commented.

The 2009 H1N1 influenza pandemic occurred during the middle of the study, he noted. "We expected a slight to moderate increase in exacerbations during this time," he said. But surprisingly, the rate was half as high during a period after the first documented case of H1N1 flu (April 2009 to March 2010) as during a period before (April 2008 to March 2009).

The investigators did not have data on the patients' immunization status. "One thing we have learned from POET and H1N1 is [that] it's very important to have the vaccination status for influenza at baseline," he commented. "This easily can be monitored and recorded, and we should have [these] data because we have problems explaining the difference in exacerbations before and during H1N1 without any vaccination status."

"Irrespective of the efficacy results of large COPD trials such as POET ... we can learn much from studies like this," Dr. Glaab added. "And perhaps this may have an impact on how we plan and design studies on exacerbations more efficiently and more effectively in the future."

Dr. Glaab is an employee of Boehringer Ingelheim. The trial was funded by Boehringer Ingelheim and Pfizer.

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