Risk assessment of ischemic stroke associated pneumonia

Cerebral stroke is a disease with a high disability rate and a high fatality rate. This study was undertaken to assess the risk of stroke associated pneumonia (SAP) in patients with ischemic stroke using A2DS2 score.

Altogether 1 279 patients with ischemic stroke who were treated in our department from 2009 to 2011 were retrospectively analyzed with A2DS2 score. A2DS2 score was calculated as follows: age ≥75 years=1, atrial fibrillation=1, dysphagia=2, male sex=1; stroke severity: NIHSS score 0-4=0, 5-15=3, ≥16=5. The patients were divided into three groups according to A2DS2 score: 620 in score 0 group, 383 in score 1-9 group, and 276 in score ≥10 group. The three groups were comparatively analyzed. The diagnostic criteria for SAP were as follows: newly emerging lesions or progressively infiltrating lesions on post-stroke chest images combined with more than two of the following clinical symptoms of infection: (1) fever ≥38 °C; (2) newly occurred cough, productive cough or exacerbation of preexisting respiratory tract symptoms with or without chest pain; (3) signs of pulmonary consolidation and/or wet rales; (4) peripheral white blood cell count ≥10×10(9)/L or ≤4×10(9)/L with or without nuclear shift to left, while excluding some diseases with clinical manifestations similar to pneumonia, such as tuberculosis, pulmonary tumors, non-infectious interstitial lung disease, pulmonary edema, pulmonary embolism and atelectasis. The incidence and mortality of SAP as well as the correlation with ischemic stroke site were analyzed in the three groups respectively. Mean± standard deviation was used to represent measurement data with normal distribution and Student's t test was used. The chi-square test was used to calculate the percentage for enumeration data.

The incidence of SAP was significantly higher in the A2DS2 score≥10 group than that in the score 1-9 and score 0 groups (71.7% vs. 22.7%, 71.7% vs. 3.7%, respectively), whereas the mortality in the score≥10 group was significantly higher than that in the score 1-9 and score 0 groups (16.7% vs. 4.96%, 16.7% vs. 0.3%, respectively). The incidences of cerebral infarction in posterior circulation and cross-MCA, ACA distribution areas were significantly higher than those in the SAP group and in the non-SAP group (35.1% vs.10.1%, 11.4% vs. 7.5%, respectively). The incidence of non-fermentative bacteria infection was significantly increased in the score≥10 group.

A2DS2 score provides a basis for risk stratification of SAP. The prevention of SAP needs to be strengthened in acute ischemic stroke patients with a A2DS2 score≥10.