While patients with chronic obstructive pulmonary disease have a higher risk of stroke than the general population, patients who have frequent exacerbations of their illness actually have a reduced risk of stroke than those with infrequent exacerbations.
New research suggests that while patients with chronic obstructive pulmonary disease (COPD) have a higher risk of stroke than the general population, COPD patients who have frequent exacerbations (FE) of their illness are not at greater risk of stroke than those with infrequent exacerbations (IE). It is thought that chronic inflammation associated with COPD contributes to increased risk of stroke, and exacerbation frequency is associated with a rise in inflammation.
The study, published in the International Journal of COPD, by Dr Claire Windsor of the London School of Hygiene and Tropical Medicine and colleagues, followed 6441 COPD patients with a first stroke between January 2004 and December 2013 and 19,323 COPD patients matched for age, sex, and general practice who did not have a stroke (controls). FEs were defined as COPD patients with 2 or more exacerbations; IEs had 1 or fewer exacerbations in the year prior to stroke.
There was no evidence that patients with FEs had an increased risk of stroke compared with patients with IEs. Instead, there was evidence that the risk of stroke decreased with each exacerbation of COPD experienced per year. FE patients had a 33% lower odds of hemorrhagic stroke than IE patients.
“However, this association is likely to be more complex than exacerbation numbers alone and we recommend further exploration of this association through investigation of stroke risk and the severity, duration, treatment of exacerbations, and concurrent treatment of cardiovascular risk factors,” the authors wrote.
The researchers gave 2 plausible reasons why a COPD patients with more exacerbations would have a lower risk of stroke: first, treatment for exacerbations, oral glucocorticoids, has been shown to reduce strike risk; and second, each exacerbation resulted in contact with healthcare services, which may have resulted in better management of other risk factors for stroke.
Based on these findings, the investigators concluded that exacerbation frequency is unlikely to be the reason for increased stroke risk among COPD patients. They noted that 2 key strengths of their study was the size of their data set, which had sufficient power to detect very small differences for the primary outcome, and the fact that it was community based, so that it is generalizable to the majority of COPD patients.