Accuracy of Neurovascular Fellows' Prognostication of Outcome After Subarachnoid Hemorrhage

Background and Purpose—

The purpose of this study was to determine the accuracy and optimal timing of physician prognostication in patients with subarachnoid hemorrhage, a prototypical neurological disease characterized by variable outcomes and frequent disability.

Methods—

From October 2009 to April 2010, treating neurologists at a tertiary care academic medical center made daily predictions of the modified Rankin Scale at 6 months for consecutive patients with subarachnoid hemorrhage. Actual functional outcomes at 6 months were determined by phone interview and dichotomized into good (modified Rankin Scale 0–2) and poor (modified Rankin Scale 3–6) outcomes. Descriptive statistics were used to assess the accuracy of prognostications. Multiple logistic regression and generalized estimating equations were used to assess changes in prognostication accuracy over time and the relationship between prognostication accuracy and clinical factors.

Results—

Physicians made 648 prognostications for 66 patients. Overall accuracy ranged from 78% to 88%. Among patients predicted to have a good outcome, 81% (95% CI, 71%–92%) actually had a good outcome, whereas 88% (95% CI, 77%–99%) of patients predicted to do poorly had poor outcomes. No significant trends were seen in prognostication accuracy over time during the hospital course ( P =0.72). Increasing age, infection, mechanical ventilation, hydrocephalus, and seizures all significantly worsened physician accuracy.

Conclusions—

Neurologists were generally but not perfectly accurate in their prognostications of functional outcomes. The accuracy of prognoses did not correlate with the hospital day on which they were made but was affected by clinical factors that can cloud the neurological examination.

Cost-Effectiveness of Dabigatran Compared With Warfarin for Stroke Prevention in Patients With Atrial Fibrillation and Prior Stroke or Transient Ischemic Attack

Background and Purpose—

The cost-effectiveness of dabigatran for stroke prevention in patients with atrial fibrillation and prior stroke or transient ischemic attack has not been directly assessed.

Methods—

A Markov decision model was constructed using data from the Randomized Evaluation of Long-Term Therapy (RE-LY) trial, other trials of warfarin therapy for atrial fibrillation, and the published cost of dabigatran. We compared the cost and quality-adjusted life expectancy associated with 150 mg dabigatran twice daily versus warfarin therapy targeted to an international normalized ratio of 2 to 3. The target population was a cohort of patients aged ≥70 years with nonvalvular atrial fibrillation, prior stroke or transient ischemic attack, and no contraindication to anticoagulation.

Results—

In the base case, dabigatran was associated with 4.27 quality-adjusted life-years compared with 3.91 quality-adjusted life-years with warfarin. Dabigatran provided 0.36 additional quality-adjusted life-years at a cost of $9000, yielding an incremental cost-effectiveness ratio of $25 000. In sensitivity analyses, the cost-effectiveness of dabigatran was inversely related to the quality of international normalized ratio control achieved with warfarin therapy. In Monte Carlo analysis, dabigatran was cost-effective in 57% of simulations using a threshold of $50 000 per quality-adjusted life-year and 78% of simulations using a threshold of $100 000 per quality-adjusted life-year.

Conclusions—

Dabigatran appears to be cost-effective relative to warfarin for stroke prevention in patients with atrial fibrillation and prior stroke or transient ischemic attack. Our analysis is limited by its reliance on data from a substudy of a single randomized trial, and our results may not apply in settings with uncommonly good international normalized ratio control using warfarin.

Abstract 2694: Trajectory and Predictors of Functional Recovery after Subarachnoid Hemorrhage

Background: SAH frequently causes severe disability or death. Although there are extensive data on predictors of survival after SAH, there are few data on the trajectory and predictors of functional recovery after hospital discharge.

Methods: We prospectively gathered data from October 2009 to April 2010 on consecutive patients with non-traumatic SAH who survived to hospital discharge. Functional outcomes based on the modified Rankin Scale (mRS) score were calculated at discharge from chart review and at six months via a standardized telephone interview. Good functional status was defined as an mRS score of 0 to 2, and poor status as an mRS score of 3 to 6. Descriptive statistics were used to assess the trajectory of functional recovery from hospital discharge to 6 months, and ordinal logistic regression was used to identify clinical factors associated with recovery, defined as the difference between the 6-month and discharge mRS scores.

Results: Sixty-six of 70 patients hospitalized with SAH during the study period had 6-month outcome data, and 53 (80%) survived to hospital discharge and were included in our analysis. Mean age was 54 (13) years, and 33 (62%) were women. Median (IQR) Hunt-Hess grade, Fisher score, and GCS at presentation were 2 (2-4), 3 (2-4), and 15 (9-15), respectively. SAH was due to aneurysms (79%), perimesencephalic hemorrhages (9%), and other causes (12%). Most patients were discharged home (70%). Median (IQR) mRS score was 3 (2-4) at discharge and 2 (1-2) at 6 months. Of the 29 patients with poor functional status at discharge, 16 (55%) improved to good functional status at 6 months ( Figure ). Patients had greater odds of improvement between their discharge and 6-month mRS scores if they were older (OR per decade 2.2, 95% CI 1.4-3.5), had hydrocephalus (OR 7.7, 95% CI 1.7-35.2), had higher Hunt-Hess grades (OR per point 2.3, 95% CI 1.2-4.5), or were discharged to home (OR 10.1, 95% CI 1.9-53.8), while higher Fisher scores were associated with less recovery (OR per point 0.4, 95% CI 0.2-0.7).

Conclusions: A substantial proportion of patients with SAH who have disability at discharge have significant functional recovery at 6 months.

Abstract 172: Cost-Effectiveness of Dabigatran Compared with Warfarin for Secondary Stroke Prevention in Patients with Atrial Fibrillation and Prior Stroke or Transient Ischemic Attack

Background: The cost-effectiveness of dabigatran for secondary stroke prevention in patients who present with atrial fibrillation (AF) and stroke or transient ischemic attack (TIA) has not been directly assessed.

Methods: A Markov decision model was constructed (Figure 1) using data from a substudy of the Randomized Evaluation of Long-Term Therapy (RE-LY) trial, other trials of warfarin therapy for AF, and the published cost of dabigatran. We compared two treatment strategies: adjusted-dose warfarin therapy with an international normalized ratio (INR) target of 2 to 3, versus dabigatran 150 mg twice daily. The target population was a cohort of patients aged 70 years and older with non-valvular AF, prior stroke or TIA, and no contraindication to anticoagulation. The model outputs were costs in 2010 U.S. dollars and quality-adjusted life-years (QALYs).

Results: In the base case, quality-adjusted life expectancy was 4.36 QALYs with dabigatran compared with 4.04 QALYs with warfarin. Dabigatran provided 0.34 additional QALYs at a cost of $9,500, yielding an incremental cost-effectiveness ratio of $28,000. In sensitivity analyses (Figure 2), the cost-effectiveness of dabigatran was influenced by patients’ age, the cost of dabigatran, the relative risk of stroke using dabigatran compared with warfarin, and the quality of INR control achieved with warfarin therapy.

Conclusions: Dabigatran appears to be cost-effective relative to warfarin for stroke prevention in patients with AF and prior stroke or TIA. Our analysis is limited by its reliance on data from a substudy of a single randomized trial, and our results may not apply in settings with atypically good INR control using warfarin.

Abstract 4039: Validation Of The Totaled Heath Risks in Vascular Events (THRIVE) Score For Predicting Outcomes After Endovascular Stroke Treatment

Background: We recently developed a novel clinical prediction tool, the Totaled Health Risks in Vascular Events (THRIVE) score, that predicts outcomes after endovascular stroke treatment. The THRIVE score, which incorporates age, NIH Stroke Scale (NIHSS) score, and three medical comorbidities (hypertension, diabetes mellitus, and atrial fibrillation), was developed using data from the MERCI and Multi MERCI Trials, two clinical trials of the Merci family of endovascular stroke treatment devices.

Methods: In order to perform external validation to demonstrate the reliability of our prediction tool, we applied the THRIVE score to patients from the Merci Registry, the largest clinical series of patients to date undergoing endovascular stroke treatment. We examined the predictive utility of the THRIVE score across the range of clinical outcomes and used Receiver-Operator Characteristics curve analysis and ordinal logistic regression to formally compare score performance in the two data sets.

Results: We find that the THRIVE score predicts good outcome, death, and the full range of the modified Rankin Scale in a similar fashion between the MERCI Trials and the Merci Registry. In Receiver-Operator Characteristics curve comparisons, the area under the curve (AUC) for the ROC curves for good outcome was not significantly different between MERCI Trial patients (AUC = 0.293, 95% C.I. = 0.231 to 0.355) and Merci Registry patients (AUC = 0.266, 95% C.I. = 0.230 to 0.302) (P = 0.47), and the AUC for the ROC curves for death was not significantly different between MERCI Trial patients (AUC = 0.692, 95% C.I. = 0.632 to 0.752) and Merci Registry patients (AUC = 0.717, 95% C.I. = 0.683 to 0.750) (P = 0.48). The THRIVE score (0 to 9) predicts mRS (0 to 6) in ordinal logistic regression in a similar fashion for the MERCI Trials (OR = 1.47, 95% C.I. 1.31 to 1.65, P < 0.001) and the Merci Registry (OR = 1.61, 95% C.I. 1.51 to 1.72, P < 0.001).

Conclusion: The THRIVE score reliably predicts outcomes after endovascular stroke treatment. The THRIVE score may be useful as a prognostic tool in clinical practice and as a means to perform severity adjustments in clinical stroke research. A THRIVE score calculator is available at www.thrivescore.org

Abstract 3513: Randomized Trial of Outpatient Cardiac Monitoring After Cryptogenic Stroke

Background: Diagnosis of atrial fibrillation (AF) as a cause of stroke or TIA is important because it identifies patients who may benefit from anticoagulation. Observational studies indicate that outpatient cardiac monitoring detects previously undiagnosed AF in 5-20% of patients with stroke, but these studies may overestimate the rate of AF if selection bias prompts analysis and publication. It is also unknown whether the yield of cardiac monitoring is higher than that of routine clinical follow-up.

Methods: In a pilot trial, we randomly assigned consecutive patients with cryptogenic ischemic stroke or high-risk TIA (ABCD 2 score ≥ 4) to wear a Cardionet mobile cardiac outpatient telemetry monitor for 21 days after discharge, or to not wear a monitor. We excluded patients with a known history of AF, AF detected by inpatient cardiac telemetry (at least 24 hours required), a definite small-vessel etiology, a source found by vascular imaging or echocardiography, an obvious culpable systemic illness such as endocarditis, or inability to provide written, informed consent. All patients received routine clinical follow-up from their primary care physician and neurologist. We contacted patients and their physicians 3 months after discharge and used validated questionnaires to inquire about clinical diagnoses of AF and recurrent stroke or TIA.

Results: The target enrollment of 40 patients was completed over 18 months. The mean age was 67 years (± 13), 23 (58%) were men, and 32 (80%) had at least one vascular risk factor; the baseline characteristics of our cohort were broadly similar to those in prior observational studies of cardiac monitoring after stroke. Our prespecified feasibility criteria were met, with full follow-up on 38 patients (95%) and successful completion of monitoring in 15 of the 20 patients (75%) randomized to monitoring. Overall, patients wore monitors for 64% of the assigned days. No patient in either study arm received a diagnosis of AF. Cardiac monitoring revealed AF in zero patients (0%, 95% CI 0-17%), brief episodes (< 10 seconds) of atrial tachycardia in two patients (10%, 95% CI 1-32%) and nonsustained ventricular tachycardia in two patients (10%, 95% CI 1-32%). There were no recurrent strokes; recurrent TIAs occurred in two patients assigned to the control group.

Conclusions: The results of our pilot trial indicate that randomizing patients to outpatient cardiac monitoring after stroke is feasible. However, rates of AF detection were lower than expected, which may be due to publication bias in prior observational studies or selection of lower risk patients in our trial. Furthermore, 25% of patients assigned to undergo monitoring were not compliant. These results suggest that an adequately powered randomized trial of cardiac monitoring after stroke may require large numbers of participants.

Abstract 2779: The Safety of Intravenous Thrombolysis for Ischemic Stroke in Patients With Pre-Existing Cerebral Aneurysms: A Retrospective, Hospital-Based Study

Background and Purpose: Unruptured cerebral aneurysms are currently considered a contraindication to intravenous tissue plasminogen activator (IV tPA) for acute ischemic stroke. This is due to a theoretical increase in the risk of hemorrhage from aneurysm rupture, although it is unknown whether this risk is significant. We sought to determine the safety of IV tPA administration in a cohort of patients with pre-existing aneurysms.

Methods: We reviewed the medical records of patients treated for acute ischemic stroke with IV tPA during an 11-year period at two academic medical centers. We identified a subset of patients with unruptured cerebral aneurysms present on pre-thrombolysis vascular imaging. Our outcomes of interest were any intracranial hemorrhage (ICH), symptomatic ICH, and subarachnoid hemorrhage (SAH). Fisher’s exact test was used to compare the rates of hemorrhage among patients with and without aneurysms.

Results: We identified 236 eligible patients, of whom 22 had unruptured cerebral aneurysms. The rate of ICH among patients with aneurysms (14%, 95% CI 3-35%) did not significantly differ from the rate among patients without aneurysms (19%, 95% CI 14-25%). None of the patients with aneurysms developed symptomatic ICH (0%, 95% CI 0-15%), compared with 10 of 214 patients without aneurysms (5%, 95% CI 2-8%). Similar proportions of patients developed SAH (5%, 95% CI 0-23% versus 6%, 95% CI 3-10%).

Conclusion: Our findings suggest that IV tPA for acute ischemic stroke is safe to administer in patients with pre-existing cerebral aneurysms as the risk of aneurysm rupture and symptomatic ICH is low.

Abstract 2323: Statin Use and Discharge Disposition After Ischemic Stroke Hospitalization

Objective: To determine whether statin use is associated with improved discharge disposition after ischemic stroke.

Methods: We analyzed 12,689 patients with ischemic stroke over a 7 year period at 17 hospitals in Kaiser Permanente Northern California. We used multivariable generalized ordinal logistic regression and instrumental variable analysis of treatment patterns by hospital to control for the possibility of confounding.

Results: Statin users before and during stroke hospitalization were more likely to be discharged home (54.9% for statin users, 46.3% for statin non-users) and less likely to die in hospital (5.3% for statin users, 10.3% for statin non-users). Patients who underwent statin withdrawal in-hospital were less likely to be discharged home (39.1% for statin withdrawal, 54.9% for statin continuation) and more likely to die in hospital (22.3% for statin withdrawal, 5.3% for statin continuation). Users of higher statin doses (>60 mg / day) were even more likely to be discharged home (62.5% for high dose statin, 56.5% for usual dose statin, and 47.4% for no statin) and less likely to die in hospital in-hospital (3.5% for high dose statin, 5.6% for usual dose statin, and 10.6% for no statin). These results were confirmed by multivariable analysis. The association of statin use and improved outcomes was also confirmed by instrumental variable analysis of treatment patterns by hospital, and thus this association cannot be explained by confounding at the individual patient level.

Conclusions: Statin use is associated with improved discharge disposition after ischemic stroke, particularly at higher doses.

The effect of decompressive hemicraniectomy on brain temperature after severe brain injury

BACKGROUND

Animal studies have shown that even a small temperature elevation of 1°C can cause detrimental effects after brain injury. Since the skull acts as a potential thermal insulator, we hypothesized that decompressive hemicraniectomy facilitates surface cooling and lowers brain temperature.

METHODS

Forty-eight patients with severe brain injury (TBI = 38, ICH = 10) with continuous brain temperature monitoring were retrospectively studied and grouped into "hemicraniectomy" (n = 20) or "no hemicraniectomy" (n = 28) group. The paired measurements of core body (T Core) and brain (T Br) temperature were recorded at 1-min intervals over 12 ± 7 days. As a surrogate measure for the extent of surface heat loss from the brain, ∆T Core-Br was calculated as the difference between T Core and T Br with each recording. In order to accommodate within-patient temperature correlations, mixed-model regression was used to assess the differences in ∆T Core-Br between those with and without hemicraniectomy, adjusted for core body temperature and diagnosis.

RESULTS

A total of 295,883 temperature data pairs were collected (median [IQR] per patient: 5047 [3125-8457]). Baseline characteristics were similar for age, sex, diagnosis, incidence of sepsis, Glasgow Coma Scale score, ICU mortality, and ICU length of stay between the two groups. The mean difference in ∆T Core-Br was 1.29 ± 0.87°C for patients with and 0.80 ± 0.86°C for patients without hemicraniectomy (P < 0.0001). In mixed-model regression, accounting for temperature correlations within patients, hemicraniectomy and higher T Core were associated with greater ∆T Core-Br (hemicraniectomy: estimated effect = 0.60, P = 0.003; T Core: estimated effect = 0.21, P < 0.0001).

CONCLUSIONS

Hemicraniectomy is associated with modestly but significantly lower brain temperature relative to core body temperature.

Statin use during ischemic stroke hospitalization is strongly associated with improved poststroke survival

BACKGROUND AND PURPOSE

Statins reduce infarct size in animal models of stroke and have been hypothesized to improve clinical outcomes after ischemic stroke. We examined the relationship between statin use before and during stroke hospitalization and poststroke survival.

METHODS

We analyzed records from 12 689 patients admitted with ischemic stroke to any of 17 hospitals in a large integrated healthcare delivery system between January 2000 and December 2007. We used multivariable survival analysis and grouped-treatment analysis, an instrumental variable method that uses treatment differences between facilities to avoid individual patient-level confounding.

RESULTS

Statin use before ischemic stroke hospitalization was associated with improved survival (hazard ratio, 0.85; 95% CI, 0.79-0.93; P<0.001), and use before and during hospitalization was associated with better rates of survival (hazard ratio, 0.59; 95% CI, 0.53-0.65; P<0.001). Patients taking a statin before their stroke who underwent statin withdrawal in the hospital had a substantially greater risk of death (hazard ratio, 2.5; 95% CI, 2.1-2.9; P<0.001). The benefit was greater for high-dose (>60 mg/day) statin use (hazard ratio, 0.43; 95% CI, 0.34-0.53; P<0.001) than for lower dose (<60 mg/day) statin use (hazard ratio, 0.60; 95% CI, 0.54-0.67; P<0.001; test for trend P<0.001), and earlier treatment in-hospital further improved survival. Grouped-treatment analysis showed that the association between statin use and survival cannot be explained by patient-level confounding.

CONCLUSIONS

Statin use early in stroke hospitalization is strongly associated with improved poststroke survival, and statin withdrawal in the hospital, even for a brief period, is associated with worsened survival.

Validation of the Stroke Prognostic Instrument-II in a large, modern, community-based cohort of ischemic stroke survivors

BACKGROUND AND PURPOSE

The risk of recurrent stroke in the modern era of secondary stroke prevention is not well defined. Several prediction models, including the Stroke Prognostic Instrument-II (SPI-II), have been created to identify patients at highest risk, but their performance in modern populations has been infrequently tested. We aimed to assess the 1-year risk of recurrence after hospital discharge in a recent, large, community-based cohort of patients with ischemic stroke and to validate the SPI-II prediction model in this cohort.

METHODS

From 2004 through 2006, 5575 patients with acute ischemic stroke were prospectively identified and followed for recurrent events. Kaplan-Meier statistics were used to analyze the cumulative incidence of recurrent ischemic stroke. Harrell c-statistic was calculated to determine the performance of SPI-II in predicting stroke or death at 1 year, and the log-rank test was used to compare the differences among low-, middle-, and high-risk groups.

RESULTS

Among 5575 patients with ischemic stroke, recurrence was observed in 221 during the subsequent year. Kaplan-Meier estimates of cumulative rates of recurrent stroke were 2.5%, 3.6%, and 4.8% at 3, 6, and 12 months, respectively. Rates of stroke or death for SPI-II in the low-, middle-, and high-risk groups were 8.2%, 24.5%, and 35.6%, respectively (trend, P=0.001). The c-statistic for SPI-II was 0.62 (95% CI, 0.61-0.64).

CONCLUSIONS

The modern 1-year rate of recurrent stroke after hospital discharge is low but still substantial at 4.8%. SPI-II is a modestly effective tool in identifying patients with ischemic stroke at highest risk of developing recurrence or death.

A randomized trial of hypothesis-driven vs screening neurologic examination

OBJECTIVE

We hypothesized that trainees would perform better using a hypothesis-driven rather than a traditional screening approach to the neurologic examination.

METHODS

We randomly assigned 16 medical students to perform screening examinations of all major aspects of neurologic function or hypothesis-driven examinations focused on aspects suggested by the history. Each student examined 4 patients, 2 of whom had focal deficits. Outcomes of interest were the correct identification of patients with focal deficits, number of specific deficits detected, and examination duration. Outcomes were assessed by an investigator blinded to group assignments. The McNemar test was used to compare the sensitivity and specificity of the 2 examination methods.

RESULTS

Sensitivity was higher with hypothesis-driven examinations than with screening examinations (78% vs 56%; p = 0.046), although specificity was lower (71% vs 100%; p = 0.046). The hypothesis-driven group identified 61% of specific examination abnormalities, whereas the screening group identified 53% (p = 0.008). Median examination duration was 1 minute shorter in the hypothesis-driven group (7.0 minutes vs 8.0 minutes; p = 0.13).

CONCLUSIONS

In this randomized trial comparing 2 methods of neurologic examination, a hypothesis-driven approach resulted in greater sensitivity and a trend toward faster examinations, at the cost of lower specificity, compared with the traditional screening approach. Our findings suggest that a hypothesis-driven approach may be superior when the history is concerning for an acute focal neurologic process.

Factors associated with fainting: before, during and after whole blood donation

BACKGROUND  Whole blood (WB) donation encompasses several periods during which some donors faint. Identification of factors associated with fainting during each period should guide intervention strategies. Reducing faint reactions may reduce donor injuries and disability. METHODS  Blood donation was divided into three periods: Period 1 - registration; Period 2 - phlebotomy; and Period 3 - post-phlebotomy. Period 3 consists of two sub-periods (3A - on-site and 3B - off-site). For each Period, stratified rates of fainting in relation to various donor and donation characteristics were calculated and multivariable logistic regression analyses to identify factors associated with fainting were conducted. Donor injuries in each period were also analysed. RESULTS  Of the 956 766 donors registered in 2007, 554 534 (58%) donated WB. There were 43 fainting episodes and two injuries in Period 1 and 1520 faints and 73 injuries in Periods 2 and 3. Regression analyses showed that youth and donor first-time status are associated with fainting in all periods; but most significantly in Period 1. Small estimated blood volume is notably not a factor in Period 1 but is significant in Periods 2 and 3. The highest injury rate is seen in Period 3A (0·07 and 0·09/1000 donations) for male and female donors, respectively. CONCLUSIONS  Variability in factors associated with fainting across defined periods of the donation process suggest differing underlying mechanisms and the possibility that interventions for the reactions most associated with injury during each time period can be designed. The highest rate of injury per donation occurred in ambulating donors.