The CHADS2 Components Are Associated with Stroke-Related In-hospital Mortality in Patients with Atrial Fibrillation

Background The CHADS2 score predicts stroke risk in patients with atrial fibrillation. Although strokes caused by atrial fibrillation carry the highest mortality when compared with other etiologies, it is not known whether the CHADS2 score predicts stroke-related mortality in patients with atrial fibrillation. We hypothesized that higher CHADS2 scores would be associated with higher stroke-related in-hospital mortality. Methods Data were obtained from administrative claims data from all emergency department encounters and hospitalizations at California's nonfederal acute care hospitals between 2008 and 2011. Patients with atrial fibrillation and an admission for acute stroke were identified using appropriate International Classification of Diseases, Ninth Revision (ICD-9), Clinical Modification codes. Age and ICD-9 codes for hypertension, diabetes, congestive heart failure, and prior stroke were used to calculate the CHADS2 score of patients with atrial fibrillation. The primary outcome was in-hospital stroke mortality and the primary predictor was CHADS2 score. A multivariate logistic regression model adjusted for sex and race was used to determine the odds ratio (OR) and 95% confidence interval (CI) for the association between CHADS2 and mortality. Results Between January 1, 2008, and December 31, 2011, 25,599 patients with atrial fibrillation were hospitalized with a stroke. The odds of in-hospital mortality was significantly higher with a CHADS2 score of 2 more versus less than 2 (OR, 1.15; 95% CI, 1.08-1.23); however, there was no dose-response association between the CHADS2 score and in-hospital mortality. Among the individual CHADS2 score items, factors associated with increased in-hospital mortality were congestive heart failure (OR, 1.61; 95% CI, 1.53-1.70), age 75 years or older (OR, 1.27; 95% CI, 1.19-1.35), and diabetes (OR, 1.24; 95% CI, 1.14-1.35). Conclusions Unlike prior studies, our studies show that the prestroke CHADS2 score is of limited use in predicting in-hospital mortality in ischemic stroke hospitalizations in patients with atrial fibrillation.