Using Radiological Data to Estimate Ischemic Stroke Severity.

BACKGROUND: Risk-adjusted poststroke mortality has been proposed for use as a measure of stroke care quality. Although valid measures of stroke severity (e.g., the National Institutes of Health Stroke Scale [NIHSS]) are not typically available in administrative datasets, radiology reports are often available within electronic health records. We sought to examine whether admission head computed tomography data could be used to estimate stroke severity. MATERIALS AND METHODS: Using chart review data from a cohort of acute ischemic stroke patients (1998-2003), we developed a radiographic measure ([BIS]) of stroke severity in a two-third development set and assessed in a one-third validation set. The retrospective NIHSS was dichotomized as mild/moderate (<10) and severe (≥10). We compared the association of this radiographic score with NIHSS and in-hospital mortality at the patient level. RESULTS: Among 1348 stroke patients, 86.5% had abnormal findings on initial head computed tomography. The c-statistic for the BIS for modeling severe stroke (development, .581; validation, .579) and in-hospital mortality (development, .623; validation, .678) were generated. CONCLUSIONS: Although the c-statistics were only moderate, the BIS provided significant risk stratification information with a 2-variable score. Until administrative data routinely includes a valid measure of stroke severity, radiographic data may provide information for use in risk adjustment.

Thrombocytopenia and in-hospital mortality risk among ischemic stroke patients.

BACKGROUND: Thrombocytopenia has been associated with increased mortality in nonstroke conditions. Because its role in acute ischemic stroke is less well understood, we sought to determine whether thrombocytopenia at admission for acute ischemic stroke was associated with in-hospital mortality. METHODS: We used data from a retrospective cohort of stroke patients (1998-2003) at 5 U.S. hospitals. Risk factors considered included conditions that can lead to thrombocytopenia (e.g., liver disease), increase bleeding risk (e.g., hemophilia), medications with antiplatelet effects (e.g., aspirin), and known predictors of mortality (e.g., National Institutes of Health Stroke Scale and Charlson Comorbidity Index scores). Logistic regression modeling evaluated the adjusted association between thrombocytopenia, defined as platelets <100,000/µL, and in-hospital mortality. RESULTS: Among 1233 acute ischemic stroke patients, thrombocytopenia was present in 2.3% (n = 28). A total of 6.1% (n = 75) of patients died in the hospital. In unadjusted analyses, thrombocytopenia was associated with higher mortality (8/28 [28.6%] v 67/1205 [5.6%]; P < .0001). Thrombocytopenia was also independently associated with in-hospital mortality after adjustment for National Institutes of Health Stroke Scale score and comorbidities, with an odds ratio of 6.6 (95% confidence interval 2.3-18.6). CONCLUSIONS: Admission thrombocytopenia among patients presenting with acute ischemic stroke predicts in-hospital mortality.

Anemia is associated with poor outcomes in patients with less severe ischemic stroke.

Anemia is a known predictor of in-hospital mortality among patients with such vascular conditions as acute myocardial infarction, congestive heart failure, and chronic kidney disease. The role of anemia in patients with acute ischemic stroke is less well understood. We sought to examine the association between anemia at hospital admission and the combined outcome of in-hospital mortality and discharge to hospice in patients with acute ischemic stroke. We evaluated data from a retrospective cohort of consecutive ischemic stroke patients presenting within 48 hours of symptom onset at 5 hospitals between 1998 and 2003. Anemia was defined as an admission hematocrit value of <30%. Less severe stroke was defined as an admission National Institutes of Health Stroke Scale score of <10. The outcome was the combined endpoint of in-hospital mortality or discharge to hospice. Among 1306 patients with stroke, anemia was present on admission in 6.4%, and the combined outcome of death or discharge to hospice was present in 10.1%. Anemia was not associated with outcome in patients with severe stroke (anemia, 17.2% [5 of 29] vs no anemia, 28,4% [98 of 345]; P = .20), but was associated with outcome in patients with less severe stroke (anemia, 13.0% [7 of 54] vs no anemia, 2.5% [22 of 878]; P < .0001). After adjustment for stroke severity, admission anemia was independently associated with outcome in patients with less severe stroke (adjusted odds ratio, 4.17; 95% confidence interval, 1.47-11.90), but not in patients with more severe strokes (adjusted odds ratio, 0.82; 95% confidence interval, 0.30-2.22). Our data indicate that anemia is associated with in-hospital mortality or discharge to hospice in patients with less severe ischemic stroke.

Derivation and validation of a clinical system for predicting pneumonia in acute stroke.

AIMS: We derived and validated a clinical prediction rule that can be used to predict post-stroke pneumonia. METHODS: We conducted a retrospective cohort study of patients admitted to hospital with a stroke. The cohort was subdivided into a derivation group and a validation group. Within the derivation group, a point scoring system was developed to predict pneumonia based on a logistic regression model. The point scoring system was then tested within the validation group. RESULTS: Of the 1,363 patients with stroke, 10.5% of patients experienced new pneumonia. The most points were assigned for abnormal swallowing result and history of pneumonia (4 points), followed by greater NIHSS score (3 points), patient being 'found down' at symptom onset (3 points), and age >70 years (2 points). A 3-level classification system was created denoting low, medium and high risks of pneumonia, which accurately predicted pneumonia in the validation group. The discriminatory accuracy of the 3-level clinical prediction rule exceeded the acceptable range in both the derivation group (c statistic: 0.78) and validation group (c statistic: 0.76). CONCLUSION: A simple scoring system was derived and validated. This clinical scoring system may better identify stroke patients who are at high risk of developing new pneumonia.

Prevalence, predictors, and outcomes of poststroke falls in acute hospital setting.

Falls are a serious medical complication following stroke. The objectives of this study were to (1) confirm the prevalence of falls among patients with stroke during acute hospitalization, (2) identify factors associated with falls during the acute stay, and (3) examine whether in-hospital falls were associated with loss of function after stroke (new dependence at discharge). We completed a secondary analysis of data from a retrospective cohort study of patients with ischemic stroke who were hospitalized at one of four hospitals. We used logistic regression to identify factors associated with inpatient falls and examine the association between falls and loss of function. Among 1,269 patients with stroke, 65 (5%) fell during the acute hospitalization period. We found two characteristics independently associated with falls: greater stroke severity (National Institutes of Health Stroke Scale [NIHSS] ≥8, adjusted odds ratio [OR] = 3.63, 95% confidence interval [CI]: 1.46-9.00) and history of anxiety (adjusted OR = 4.90, 95% CI: 1.70-13.90). Falls were independently associated with a loss of function (adjusted OR = 9.85, 95% CI: 1.22-79.75) even after adjusting for age, stroke severity, gait abnormalities, and past stroke. Stroke severity (NIHSS >8) may be clinically useful during the acute inpatient setting in identifying those at greatest risk of falling. Given the association between falls and poor patient outcomes, rehabilitation interventions should be implemented to prevent falls poststroke.

Processes of care associated with acute stroke outcomes.

BACKGROUND: Many processes of care have been proposed as metrics to evaluate stroke care. We sought to identify processes of stroke care that are associated with improved patient outcomes after adjustment for both patient characteristics and other process measures. METHODS: This retrospective cohort study included patients 18 years or older with an ischemic stroke or transient ischemic attack (TIA) onset no more than 2 days before admission and a neurologic deficit on admission. Patients were excluded if they resided in a skilled nursing facility, were already admitted to the hospital at stroke onset, or were transferred from another acute-care facility. The combined outcome included in-hospital mortality, discharge to hospice, or discharge to a skilled nursing facility. Seven processes of stroke care were evaluated: fever management, hypoxia management, blood pressure management, neurologic evaluation, swallowing evaluation, deep vein thrombosis (DVT) prophylaxis, and early mobilization. Risk adjustment included age, comorbidity (medical history), concomitant medical illness present at admission, preadmission symptom course, prestroke functional status, code status, stroke severity, nonneurologic status, modified APACHE (Acute Physiology and Chronic Health Evaluation) III score, and admission brain imaging findings. RESULTS: Among 1487 patients, the outcome was observed in 239 (16%). Three processes of care were independently associated with an improvement in the outcome after adjustment: swallowing evaluation (adjusted odds ratio [OR], 0.64; 95% confidence interval [CI], 0.43-0.94); DVT prophylaxis (adjusted OR, 0.60; 95% CI, 0.37-0.96); and treating all episodes of hypoxia with supplemental oxygen (adjusted OR, 0.26; 95% CI, 0.09-0.73). CONCLUSION: Outcomes among patients with ischemic stroke or TIA can be improved by attention to swallowing function, DVT prophylaxis, and treatment of hypoxia.