Background: COPD recently overtook stroke as the third leading cause of death in the United States. Intriguingly, smoking is an important shared risk factor for both stroke and COPD; COPD patients have baseline cerebral hypoxia and hypercapnia that could potentially exacerbate vascular brain injury; and stroke patients with COPD are at higher risk of aspiration than those without COPD. Yet, relatively little is known about the prevalence of COPD among stroke patients or its impact on outcomes after an index stroke.
Objective: To assess prevalence of COPD among hospitalized stroke patients in a nationally representative sample and examine the effect of COPD with risk of dying in the hospital after a stroke.
Methods: Data were obtained for patients, 18 years and older, from the National Inpatient Sample from 2004-2009 (n=48,087,002). Primary discharge diagnoses of stroke were identified using ICD-9 diagnosis codes 430-432 and 433-436, of which a subset with comorbid COPD were defined with secondary ICD-9 diagnoses codes 490-492, 494, and 496. In-hospital mortality rates were calculated, and independent associations of COPD with in-hospital mortality following stroke were evaluated with logistic regression. All analysis were survey-weighted.
Results: 11.71% (95% CI 11.48-11.94) of all adult patients hospitalized for stroke had COPD. The crude and age-adjusted in-hospital mortality rates for these patients were 6.33% (95% CI 6.14-6.53) and 5.99% (95% CI 4.05-7.94), respectively. COPD was independently and modestly associated with overall stroke mortality (OR 1.03, 95% CI 1.01-1.06; p=0.02). However, when analyzed by subtype, greater risks of mortality were seen in those with intracerebral hemorrhage (OR 1.12, 95% CI 1.03-1.20; p<0.01), and ischemic stroke (OR 1.08; 95% CI 1.03-1.13, p<0.01), but not subarachnoid hemorrhage (OR 0.98, 95% CI 0.85-1.13; p=0.78). There were no statistically significant interactions between COPD and age, gender, or race.
Conclusion: 12% of hospitalized stroke patients have COPD. Presence of COPD is independently associated with higher odds of dying during ischemic stroke hospitalization. Prospective studies are needed to identify any modifiable risk factors contributing to this deleterious relationship.