Stroke risk after nonstroke emergency department dizziness presentations: a population-based cohort study

OBJECTIVE

Acute stroke is a serious concern in emergency department (ED) dizziness presentations. Prior studies, however, suggest that stroke is actually an unlikely cause of these presentations. Lacking are data on short- and long-term follow-up from population-based studies to establish stroke risk after presumed nonstroke ED dizziness presentations.

METHODS

From May 8, 2011 to May 7, 2012, patients ≥45 years of age presenting to EDs in Nueces County, Texas, with dizziness, vertigo, or imbalance were identified, excluding those with stroke as the initial diagnosis. Stroke events after the ED presentation up to October 2, 2012 were determined using the BASIC (Brain Attack Surveillance in Corpus Christi) study, which uses rigorous surveillance and neurologist validation. Cumulative stroke risk was calculated using Kaplan-Meier estimates.

RESULTS

A total of 1,245 patients were followed for a median of 347 days (interquartile range [IQR] = 230-436 days). Median age was 61.9 years (IQR = 53.8-74.0 years). After the ED visit, 15 patients (1.2%) had a stroke. Stroke risk was 0.48% (95% confidence interval [CI] = 0.22-1.07%) at 2 days, 0.48% (95% CI = 0.22-1.07%) at 7 days, 0.56% (95% CI = 0.27-1.18%) at 30 days, 0.56% (95% CI = 0.27-1.18%) at 90 days, and 1.42% (95% CI = 0.85-2.36%) at 12 months.

INTERPRETATION

Using rigorous case ascertainment and outcome assessment in a population-based design, we found that the risk of stroke after presumed nonstroke ED dizziness presentations is very low, supporting a nonstroke etiology to the overwhelming majority of original events. High-risk subgroups likely exist, however, because most of the 90-day stroke risk occurred within 2 days. Vascular risk stratification was insufficient to identify these cases.

Intracerebral hemorrhage mortality is not changing despite declining incidence

OBJECTIVE

To determine trends in incidence and mortality of intracerebral hemorrhage (ICH) in a rigorous population-based study.

METHODS

We identified all cases of spontaneous ICH in a South Texas community from 2000 to 2010 using rigorous case ascertainment methods within the Brain Attack Surveillance in Corpus Christi Project. Yearly population counts were determined from the US Census, and deaths were determined from state and national databases. Age-, sex-, and ethnicity-adjusted incidence was estimated for each year with Poisson regression, and a linear trend over time was investigated. Trends in 30-day case fatality and long-term mortality (censored at 3 years) were estimated with log-binomial or Cox proportional hazards models adjusted for demographics, stroke severity, and comorbid disease.

RESULTS

A total of 734 cases of ICH were included. The age-, sex-, and ethnicity-adjusted ICH annual incidence rate was 5.21 per 10,000 (95% confidence interval [CI] 4.36, 6.24) in 2000 and 4.30 per 10,000 (95% CI 3.21, 5.76) in 2010. The estimated 10-year change in demographic-adjusted ICH annual incidence rate was -31% (95% CI -47%, -11%). Yearly demographic-adjusted 30-day case fatality ranged from 28.3% (95% CI 19.9%, 40.3%) in 2006 to 46.5% (95% CI 35.5, 60.8) in 2008. There was no change in ICH case fatality or long-term mortality over time.

CONCLUSIONS

ICH incidence decreased over the past decade, but case fatality and long-term mortality were unchanged. This suggests that primary prevention efforts may be improving over time, but more work is needed to improve ICH treatment and reduce the risk of death.

Brainstem infarction and sleep-disordered breathing in the BASIC sleep apnea study

BACKGROUND

Association between cerebral infarction site and poststroke sleep-disordered breathing (SDB) has important implications for SDB screening and the pathophysiology of poststroke SDB. Within a large, population-based study, we assessed whether brainstem infarction location is associated with SDB presence and severity.

METHODS

Cross-sectional study was conducted on ischemic stroke patients in the Brain Attack Surveillance in Corpus Christi (BASIC) project. Subjects underwent SDB screening (median 13days after stroke) with a well-validated cardiopulmonary sleep apnea-testing device (n=355). Acute infarction location was determined based on review of radiology reports and dichotomized into brainstem involvement or none. Logistic and linear regression models were used to test the associations between brainstem involvement and SDB or apnea/hypopnea index (AHI) in unadjusted and adjusted models.

RESULTS

A total of 38 participants (11%) had acute infarction involving the brainstem. Of those without brainstem infarction, 59% had significant SDB (AHI⩾10); the median AHI was 13 (interquartile range (IQR) 6, 26). Of those with brainstem infarction, 84% had SDB; median AHI was 20 (IQR 11, 38). In unadjusted analysis, brainstem involvement was associated with over three times the odds of SDB (odds ratio (OR) 3.71 (95% confidence interval (CI): 1.52, 9.13)). In a multivariable model, adjusted for demographics, body mass index (BMI), hypertension, diabetes, coronary artery disease, atrial fibrillation, prior stroke/transient ischemic attack (TIA), and stroke severity, results were similar (OR 3.76 (95% CI: 1.44, 9.81)). Brainstem infarction was also associated with AHI (continuous) in unadjusted (p=0.004) and adjusted models (p=0.004).

CONCLUSIONS

Data from this population-based stroke study show that acute infarction involving the brainstem is associated with both presence and severity of SDB.

Is technologist review of raw data necessary after home studies for sleep apnea?

STUDY OBJECTIVES

As the importance of portable monitors for detection of sleep apnea increases, efficient and cost-minimizing methods for data interpretation are needed. We sought to compare in stroke patients, for whom portable studies often have particular advantages, results from a cardiopulmonary monitoring device with and without manual edits by a polysomnographic technologist.

METHODS

Participants in an ongoing stroke surveillance study in Corpus Christi, Texas, underwent sleep apnea assessments with the ApneaLink Plus device within 45 days of stroke onset. Recordings were analyzed by the device's software unedited, and again after edits were made to the raw data by a registered polysomnographic technologist. Sensitivity and specificity were calculated, with the edited data as the reference standard. Sleep apnea was defined by 3 different apnea-hypopnea index (AHI) thresholds: ≥ 5, ≥ 10, and ≥ 15.

RESULTS

Among 327 subjects, 54% were male, 59% were Hispanic, and the median age was 65 years (interquartile range: 57, 77). The median AHI for the unedited data was 9 (4, 22), and for the edited data was 13 (6, 27) (p < 0.01). Specificity was above 98% for each AHI cutoff, while sensitivity was 81% to 82%. For each cutoff threshold, the edited data yielded a higher proportion of positive sleep apnea screens (p < 0.01) by approximately 10% in each group.

CONCLUSIONS

For stroke patients assessed with a cardiopulmonary monitoring device, manual editing by a technologist appears likely to improve sensitivity, whereas specificity of unedited data is already excellent.

Meta-analysis of genome-wide association studies identifies 1q22 as a susceptibility locus for intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is the stroke subtype with the worst prognosis and has no established acute treatment. ICH is classified as lobar or nonlobar based on the location of ruptured blood vessels within the brain. These different locations also signal different underlying vascular pathologies. Heritability estimates indicate a substantial genetic contribution to risk of ICH in both locations. We report a genome-wide association study of this condition that meta-analyzed data from six studies that enrolled individuals of European ancestry. Case subjects were ascertained by neurologists blinded to genotype data and classified as lobar or nonlobar based on brain computed tomography. ICH-free control subjects were sampled from ambulatory clinics or random digit dialing. Replication of signals identified in the discovery cohort with p < 1 × 10(-6) was pursued in an independent multiethnic sample utilizing both direct and genome-wide genotyping. The discovery phase included a case cohort of 1,545 individuals (664 lobar and 881 nonlobar cases) and a control cohort of 1,481 individuals and identified two susceptibility loci: for lobar ICH, chromosomal region 12q21.1 (rs11179580, odds ratio [OR] = 1.56, p = 7.0 × 10(-8)); and for nonlobar ICH, chromosomal region 1q22 (rs2984613, OR = 1.44, p = 1.6 × 10(-8)). The replication included a case cohort of 1,681 individuals (484 lobar and 1,194 nonlobar cases) and a control cohort of 2,261 individuals and corroborated the association for 1q22 (p = 6.5 × 10(-4); meta-analysis p = 2.2 × 10(-10)) but not for 12q21.1 (p = 0.55; meta-analysis p = 2.6 × 10(-5)). These results demonstrate biological heterogeneity across ICH subtypes and highlight the importance of ascertaining ICH cases accordingly.

Neurological, functional, and cognitive stroke outcomes in Mexican Americans

BACKGROUND AND PURPOSE

Our objective was to compare neurological, functional, and cognitive stroke outcomes in Mexican Americans (MAs) and non-Hispanic whites using data from a population-based study.

METHODS

Ischemic strokes (2008-2012) were identified from the Brain Attack Surveillance in Corpus Christi (BASIC) Project. Data were collected from patient or proxy interviews (conducted at baseline and 90 days poststroke) and medical records. Ethnic differences in neurological (National Institutes of Health Stroke Scale: range, 0-44; higher scores worse), functional (activities of daily living/instrumental activities of daily living score: range, 1-4; higher scores worse), and cognitive (Modified Mini-Mental State Examination: range, 0-100; lower scores worse) outcomes were assessed with Tobit or linear regression adjusted for demographics and clinical factors.

RESULTS

A total of 513, 510, and 415 subjects had complete data for neurological, functional, and cognitive outcomes and covariates, respectively. Median age was 66 (interquartile range, 57-78); 64% were MAs. In MAs, median National Institutes of Health Stroke Scale, activities of daily living/instrumental activities of daily living, and Modified Mini-Mental State Examination score were 3 (interquartile range, 1-6), 2.5 (interquartile range, 1.6-3.5), and 88 (interquartile range, 76-94), respectively. MAs scored 48% worse (95% CI, 23%-78%) on National Institutes of Health Stroke Scale, 0.36 points worse (95% CI, 0.16-0.57) on activities of daily living/instrumental activities of daily living score, and 3.39 points worse (95% CI, 0.35-6.43) on Modified Mini-Mental State Examination than non-Hispanic whites after multivariable adjustment.

CONCLUSIONS

MAs scored worse than non-Hispanic whites on all outcomes after adjustment for confounding factors; differences were only partially explained by ethnic differences in survival. These findings in combination with the increased stroke risk in MAs suggest that the public health burden of stroke in this growing population is substantial.

Hypoglossal nerve dysfunction and sleep-disordered breathing after stroke

OBJECTIVE

This cross-sectional study of acute ischemic stroke patients examined relationships between hypoglossal nerve conduction, sleep-disordered breathing (SDB), and its severity.

METHODS

Patients within 7 days of stroke underwent nocturnal respiratory monitoring with the ApneaLink device and hypoglossal nerve conduction studies.

RESULTS

Eighteen of 52 subjects (35% [95% confidence interval: 22%, 49%]) had an abnormal hypoglossal amplitude and 23 (44% [95% confidence interval: 30%, 59%]) had an abnormal hypoglossal latency. No differences were identified in hypoglossal nerve latency or amplitude between those with (n = 26) and without (n = 26) significant SDB, defined by an apnea-hypopnea index ≥ 15. However, hypoglossal nerve conduction latency was associated (linear regression p < 0.05) with SDB severity as reflected by the apnea-hypopnea index.

CONCLUSIONS

Acute ischemic stroke patients have a high prevalence of hypoglossal nerve dysfunction. Further studies are needed to explore whether hypoglossal nerve dysfunction may be a cause or consequence of SDB in stroke patients and whether this association can provide further insight into the pathophysiology of SDB in this population.

Abstract W MP90: APOE Variants are Associated With Increased Risk of Warfarin-Related Intracerebral Hemorrhage

Background: Epsilon (e) variants in the Apolipoprotein E (APOE) gene are well-established risk factors for spontaneous intracerebral hemorrhage (s-ICH). We tested the hypothesis that APOE-e variants are also associated with warfarin-related ICH (w-ICH) and examined interactions between APOE and warfarin.

Methods: Prospective multicenter 2-stage (discovery and replication) study. ICH was classified as lobar and non-lobar based on admission head CT. In the discovery stage, w-ICH cases were matched with warfarin-exposed controls (w-controls). In replication, w-ICH cases were matched with non-warfarin controls (nw-controls). APOE was directly genotyped. Association testing was performed using multivariable logistic regression. Gene-environment interaction between APOE and warfarin was formally tested using a case only approach (combining s-ICH and w-ICH cases).

Results: The discovery stage included 316 w-ICHs (43% lobar and 57% non-lobar) and 355 w-controls. Results are presented in the Table: APOE-e2 was associated with lobar and non-lobar w-ICH, and APOE-e4 was associated with lobar but not with non-lobar w-ICH. In case-only analysis, 885 s-ICHs were combined with w-ICHs (total n=1201) and no evidence of interaction between APOE and warfarin was found (all p>0.20). The replication included 63 w-ICHs (44% lobar and 56% non-lobar) and 990 nw-controls. The distribution of APOE variants was similar in w-controls (discovery) and nw-controls (replication) for both e2 (p=0.81) and e4 (p=0.88). In replication, APOE-e2 and e4 were associated with lobar but not with non-lobar w-ICH.

Conclusions: APOE-e variants constitute strong risk factors for lobar w-ICH. An effect may also exist between APOE-e2 and non-lobar hemorrhages, but given the lack of replication larger sample sizes are required to properly assess this association. APOE exerts its effect independently of warfarin, although power limitations render this absence of interaction preliminary.

Abstract 52: Brainstem Infarction is Associated with Sleep Apnea: The BASIC Sleep Project

Background: Despite hypotheses that brainstem infarction is associated with sleep apnea (SA), no specific site of infarction has been associated with post-stroke SA in existing studies, which have been relatively small. Within a larger, population-based study, we assessed the association between infarction location and SA presence and severity.

Methods: Ischemic stroke patients in the Brain Attack Surveillance in Corpus Christi (BASIC) project had SA screening performed (median 13 days after stroke) with a validated portable respiratory monitor (ApneaLink Plus) (n=355). The apnea-hypopnea index (AHI) was used to measure SA severity; SA was defined conservatively as an AHI ≥10. Acute infarction location was determined based on review of CT and MRI reports by board-certified neurologists and dichotomized into brainstem involvement or none. Logistic and linear regression models were used to test the associations between brainstem involvement and SA or AHI in unadjusted and adjusted models.

Results: Median age was 65 (IQR: 57, 77); 55% were male. Thirty-eight (11%) had acute infarction involving the brainstem. Of those without brainstem infarction, 59% had SA; the median AHI was 13 (interquartile range (IQR) 6, 26). Of those with brainstem infarction, 84% had SA; median AHI was 20 (IQR 11, 38). In unadjusted analysis, brainstem involvement was associated with over three times the odds of SA (OR 3.71 (95% CI: 1.52, 9.13). In a multivariable model, adjusted for demographics, BMI, stroke risk factors, and stroke severity, results were similar (OR 3.76 (95% CI: 1.44, 9.81)). Similarly, brainstem infarction was associated with AHI in unadjusted (p=0.004) and adjusted models (p=0.004).

Conclusion: Acute infarction involving the brainstem was associated with both presence and severity of sleep apnea in this population-based stroke surveillance study.

Abstract 27: Sleep Apnea and Ischemic Stroke Subtype: The BASIC Sleep Project

Background: Little is known about the prevalence of sleep apnea (SA) across ischemic stroke subtypes. Given the important implications for SA screening, we tested the association between SA and ischemic stroke subtype in a population-based study.

Methods: Within the Brain Attack Surveillance in Corpus Christi Project, ischemic stroke patients were offered SA screening with the ApneaLink Plus TM device (n=355). A board-certified neurologist assigned TOAST subtype (with an additional category for nonlacunar infarctions of unknown etiology) using hospital records (diagnostic tests, imaging reports, discharge summaries). Unadjusted and adjusted (demographics, BMI, NIHSS, diabetes, history of stroke/TIA) logistic and linear regression models were used to test the association between subtype and SA or apnea-hypopnea index (AHI).

Results: Median age was 65 and 55% were male; 59% were Mexican American. Median time from stroke onset to SA screen was 13 days (IQR: 6, 21). Overall, 215 (61%) had SA (AHI ≥10). Median AHI was 13 (IQR: 6, 27). Prevalence of SA by subtype was: cardioembolism, n=42/64, 66%; large artery atherosclerosis, n=13/23, 57%; small vessel occlusion, n=17/25, 68%; other determined, n=1/2, 50%; undetermined etiology, n=65/113, 58%; and nonlacunar stroke of unknown etiology, n=80/128, 63%. Ischemic stroke subtype (other determined excluded due to small numbers) was not associated with SA in unadjusted (p=0.72) or adjusted models (p=0.91) models. Ischemic stroke subtype was not associated with AHI in unadjusted (p = 0.41) or adjusted models (p=0.62).

Conclusion: In this population-based stroke surveillance study performed in a bi-ethnic community, ischemic stroke subtype was not associated with the presence or severity of SA. Sleep apnea is likely to be present after ischemic stroke, and the subtype should not influence decisions about SA screening during inpatient hospitalizations.

Spinal gene expression profiling and pathways analysis of a CB2 agonist (MDA7)-targeted prevention of paclitaxel-induced neuropathy

AIMS

Patients receiving paclitaxel often develop peripheral neuropathies. We found that a novel selective cannabinoid CB2 receptor agonist (MDA7) prevents paclitaxel-induced mechanical allodynia in rats and mice. Here we investigated gene expression profiling in the lumbar spinal cord after 14-day treatment of MDA7 in paclitaxel animals and analyzed possible signaling pathways underlying the preventive effect of MDA7 on paclitaxel-induced neuropathy.

METHODS

Peripheral mechanical allodynia was induced in rats or mice receiving intraperitoneal (i.p.) injection of paclitaxel at a dose of 1mg/kg daily for four consecutive days. MDA7 was administered at a dose of 15mg/kg 15min before paclitaxel and then continued daily for another 10days. Whole-genome gene expression profiling in the lumbar spinal cord of MDA7 and paclitaxel-treated rats was investigated using microarray analysis. The Ingenuity pathway analysis was performed to determine the potential relevant canonical pathways responsible for the effect of MDA7 on paclitaxel-induced peripheral neuropathy.

RESULTS

We observed that the inflammatory molecular networks including tumor necrosis factor (TNF), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), transforming growth factor beta (TGFβ), and mitogen-activated protein kinases (MAPK) signaling are most relevant to the preventive effect of MDA7 on paclitaxel-induced peripheral neuropathy. In addition, genes encoding molecules that are important in central sensitization such as glutamate transporters and N-methyl-d-aspartate receptor 2B (NMDAR2B), and neuro-immune-related genes such as neuronal nitric oxide synthase (nNOS1), chemokine CX3CL1 (a mediator for microglial activation), toll-like receptor 2 (TLR2), and leptin were differentially modulated by MDA7.

CONCLUSION

The preventive effect of MDA7 on paclitaxel-induced peripheral allodynia in rats may be associated with genes involved in signal pathways in central sensitization, microglial activation, and neuroinflammation in the spinal cord.

Haiti's food and drinking water: a review of toxicological health risks

CONTEXT

The Republic of Haiti is a developing country in the Caribbean region with a history that challenges toxicologists, yet the historical panoply of toxicological hazards in Haiti has received little scholarly attention.

OBJECTIVES

The primary objectives of this paper are to review what is known about Haiti's current toxicological hazards, with a focus on chronic food-borne aflatoxin exposure and heavy metal contamination of water resources, and to compare these with previous large-scale, acute exposures to toxic substances: the 1995-1996 diethylene glycol (DEG) intoxications and the 2000-2001 ackee fruit poisonings.

METHODS

MEDLINE/PUBMED and the library website of Cornell University were searched using the terms "Haiti" and either "heavy metals," "aflatoxin", "diethylene glycol", or "ackee". The search was inclusive of articles from 1950 to 2012, and 15 out of the 37 returned were peer-reviewed articles offering original data or comprehensive discussion. One peer-reviewed article in press, two newspaper articles, two personal communications, and one book chapter from the personal databases of the authors were also referenced, making a total of 21 citations.

RESULTS

Elevated concentrations of aflatoxins (greater than 20 μg/kg) were documented for staples of the Haitian food supply, most notably peanut butters and maize. Human exposure to aflatoxin was confirmed with analysis of aflatoxin blood biomarkers. The implications of aflatoxin exposure were reviewed in the light of Haiti's age-adjusted liver cancer risk - the highest in the Caribbean region. Measurement of heavy metals in Port-au-Prince ground water showed contamination of lead and chromium in excess of the US Environmental Protection Agency's 15 μg/L Action Level for lead and 100 μg/L Maximum Contamination Level Goal for total chromium. The DEG contamination of paracetamol (acetaminophen) containing products in 1995-1996 claimed the lives of 109 children and the 2000-2001 epidemic of ackee fruit poisoning resulted in 60 cases of intoxication. Lessons for the Haitian Government. The DEG and ackee epidemics overwhelmed local Haitian public health resources. Yet, periods of 8 and 4 months, respectively, passed before the Haitian government sought assistance following the initial poisonings. To our knowledge, the Haitian government did not enact policy to promote drug safety and prevent future poisonings. This will not likely change in the near future because of the state's finance and personnel crises. While protection of its people remains the prerogative of the Haitian government, it is extremely limited in managing chemical exposure to environmental toxins, including aflatoxin and heavy metals.

CONCLUSIONS

The cases of DEG and ackee fruit poisoning demonstrate that environmental exposures to chemicals have occurred in Haiti. Current low-level exposures to aflatoxin and heavy metals highlight the risk that large-scale poisonings can occur. While awareness of toxicological hazards in Haiti must be acknowledged more widely within the government and non-governmental sectors, the lessons of these exposures are relevant to all developing countries where the capacity to discern and manage toxicological risks is absent or not yet effective.

Understanding stroke survivorship: expanding the concept of poststroke disability

BACKGROUND AND PURPOSE

Limitations in essential daily activities are common among older adults after stroke, but little is known about restrictions in their ability to participate in valued social activities. We sought to broaden our understanding of disability after stroke by characterizing poststroke participation restrictions and investigating the extent to which they are accounted for by differences in physical and cognitive capacity, aphasia/dysarthria, depressive, and anxiety symptoms.

METHODS

Data from the 2011 National Health and Aging Trends Study (NHATS) were used to identify 892 self-reported stroke survivors aged≥65 years. One-to-one propensity matching was performed on demographics and comorbidities to create a matched sample. Participation restrictions were defined as reductions/absence in social activities valued by respondents because of their health or functioning. Physical and cognitive capacity, depressive and anxiety symptoms were measured by validated scales and aphasia/dysarthria by a single question. Comparisons using survey-weighted χ2 tests and logistic regression were made.

RESULTS

Stroke survivors had more participation restrictions (32.8% versus 23.5%; odds ratio, 1.59; 95% confidence interval, 1.28-1.95; P<0.01) than controls. Differences between stroke survivors and controls in any participation restriction and several components (attending religious service, clubs/classes, and going out for enjoyment) were eliminated after adjusting for physical capacity. Depressive and anxiety symptoms and aphasia/dysarthria were independent predictors of participation restrictions.

CONCLUSIONS

Stroke survivors have more participation restrictions than can be accounted for by sociodemographic profiles and comorbidity burden. Future work aimed at improving physical capacity, reducing depressive and anxiety symptoms, and improving aphasia/dysarthria has potential to enhance participation.

Agreement between stroke patients and family members for ascertaining pre-stroke risk for sleep apnea

BACKGROUND

Ascertaining self-reported information about the risk for pre-stroke obstructive sleep apnea (OSA) in the acute stroke period is challenging as many stroke patients have deficits that hinder communication. We examined agreement between stroke patients without communication limitations and family members (proxy) in the pre-stroke risk for OSA.

METHODS

Patient-proxy pairs (n=42) were interviewed independently as part of the Brain Attack Surveillance in Corpus Christi (BASIC) Project from May 2010 to April 2011. The Berlin questionnaire was used to measure a high risk for OSA defined as the presence of at least two of the following conditions: (1) snoring behaviors/witnessed apneas, (2) daytime sleepiness, and (3) hypertension or obesity. Patient-proxy agreement was assessed using a κ coefficient.

RESULTS

Forty-three percent of patients self-identified as being at high risk for sleep apnea, and 45% of proxies identified patients as high risk. Patient-proxy agreement for high risk for pre-stroke OSA was fair (κ=0.28) with better agreement for spouses and children proxies (κ=0.38) than for other family members. Agreement also was fair for most individual questions.

CONCLUSIONS

Spouse and child proxy use of the Berlin questionnaire may be an option to assess a patient's pre-stroke likelihood of sleep apnea. Whereas prospective studies of incident stroke in patients with and without objectively confirmed sleep apnea would require formidable resources, our results suggest that an alternative strategy may involve proxy use of the Berlin questionnaire in a retrospective study design.

Persistent ischemic stroke disparities despite declining incidence in Mexican Americans

OBJECTIVE

To determine trends in ischemic stroke incidence among Mexican Americans and non-Hispanic whites.

METHODS

We performed population-based stroke surveillance from January 1, 2000 to December 31, 2010 in Corpus Christi, Texas. Ischemic stroke patients 45 years and older were ascertained from potential sources, and charts were abstracted. Neurologists validated cases based on source documentation blinded to ethnicity and age. Crude and age-, sex-, and ethnicity-adjusted annual incidence was calculated for first ever completed ischemic stroke. Poisson regression models were used to calculate adjusted ischemic stroke rates, rate ratios, and trends.

RESULTS

There were 2,604 ischemic strokes in Mexican Americans and 2,042 in non-Hispanic whites. The rate ratios (Mexican American:non-Hispanic white) were 1.94 (95% confidence interval [CI] = 1.67-2.25), 1.50 (95% CI = 1.35-1.67), and 1.00 (95% CI = 0.90-1.11) among those aged 45 to 59, 60 to 74, and 75 years and older, respectively, and 1.34 (95% CI = 1.23-1.46) when adjusted for age. Ischemic stroke incidence declined during the study period by 35.9% (95% CI = 25.9-44.5). The decline was limited to those aged ≥60 years, and happened in both ethnic groups similarly (p > 0.10), implying that the disparities seen in the 45- to 74-year age group persist unabated.

INTERPRETATION

Ischemic stroke incidence rates have declined dramatically in the past decade in both ethnic groups for those aged ≥60 years. However, the disparity between Mexican American and non-Hispanic white stroke rates persists in those <75 years of age. Although the decline in stroke is encouraging, additional prevention efforts targeting young Mexican Americans are warranted.

Individual and community determinants of calling 911 for stroke among African Americans in an urban community

BACKGROUND

African Americans receive acute stroke treatment less often than non-Hispanic whites. Interventions to increase stroke preparedness (recognizing stroke warning signs and calling 911) may decrease the devastating effects of stroke by allowing more patients to be candidates for acute stroke therapy. In preparation for such an intervention, we used a community-based participatory research approach to conduct a qualitative study exploring perceptions of emergency medical care and stroke among urban African American youth and adults.

METHODS AND RESULTS

Community partners, church health teams, and church leaders identified and recruited focus group participants from 3 black churches in Flint, MI. We conducted 5 youth (11-16 years) and 4 adult focus groups from November 2011 to March 2012. A content analysis approach was taken for analysis. Thirty-nine youth and 38 adults participated. Women comprised 64% of youth and 90% of adult focus group participants. All participants were black. Three themes emerged from the adult and youth data: (1) recognition that stroke is a medical emergency; (2) perceptions of difficulties within the medical system in an under-resourced community, and; (3) need for greater stroke education in the community.

CONCLUSIONS

Black adults and youth have a strong interest in stroke preparedness. Designs of behavioral interventions to increase stroke preparedness should be sensitive to both individual and community factors contributing to the likelihood of seeking emergency care for stroke.

Heritability estimates identify a substantial genetic contribution to risk and outcome of intracerebral hemorrhage

BACKGROUND AND PURPOSE

Previous studies suggest that genetic variation plays a substantial role in occurrence and evolution of intracerebral hemorrhage (ICH). Genetic contribution to disease can be determined by calculating heritability using family-based data, but such an approach is impractical for ICH because of lack of large pedigree-based studies. However, a novel analytic tool based on genome-wide data allows heritability estimation from unrelated subjects. We sought to apply this method to provide heritability estimates for ICH risk, severity, and outcome.

METHODS

We analyzed genome-wide genotype data for 791 ICH cases and 876 controls, and determined heritability as the proportion of variation in phenotype attributable to captured genetic variants. Contribution to heritability was separately estimated for the APOE (encoding apolipoprotein E) gene, an established genetic risk factor, and for the rest of the genome. Analyzed phenotypes included ICH risk, admission hematoma volume, and 90-day mortality.

RESULTS

ICH risk heritability was estimated at 29% (SE, 11%) for non-APOE loci and at 15% (SE, 10%) for APOE. Heritability for 90-day ICH mortality was 41% for non-APOE loci and 10% (SE, 9%) for APOE. Genetic influence on hematoma volume was also substantial: admission volume heritability was estimated at 60% (SE, 70%) for non-APOEloci and at 12% (SE, 4%) for APOE.

CONCLUSIONS

Genetic variation plays a substantial role in ICH risk, outcome, and hematoma volume. Previously reported risk variants account for only a portion of inherited genetic influence on ICH pathophysiology, pointing to additional loci yet to be identified.

Abstract WP405: Sex Differences in Post-Stroke Functional Outcomes

Background: Studies consistently show that women have less favorable functional outcomes after stroke than men but the causes are uncertain. Our objective was to assess sex differences in functional outcomes measured 90-days post event in a population-based stroke study and to identify which pre-stroke factors and clinical stroke characteristics explain sex differences.

Methods: Ischemic stroke patients (n=398) were identified from the Brain Attack Surveillance in Corpus Christi (BASIC) Project (2008-2011). Data were ascertained from in-person patient or proxy interviews (baseline and 90 days post-stroke) and medical records. Functional outcome at 90 days was measured as total ADL/IADL score (range 22-88, higher scores indicate poorer function). Tobit regression was used to estimate sex differences in outcome. To identify clinically important confounding factors, individual variables were added to age-adjusted models to determine if the sex difference changed by ≥ 5%. A final multivariable model was run including sex, age, ethnicity, and identified confounders.

Results: Median age was 69 (IQR: 57, 79) and 52% were women. In crude and age-adjusted models women scored 11.2 points (p<0.001) and 8.7 points (p<0.001) higher on the ADL/IADL score respectively. After accounting for age, stroke severity, pre-stroke functional and cognitive status, pre-stroke comorbidity index, nursing home residence, history of stroke/TIA, BMI and marital status were all clinically important confounders of the sex difference. In the final multivariable model, a sex difference in functional outcome remained, with women scoring 6.2 points higher on the ADL/IADL score than men (p<0.01).

Conclusions: Women had poorer functional outcomes post stroke even after accounting for differences in age, pre-stroke confounding factors and stroke severity. Age, pre-stroke factors and stroke severity explained about half of the total observed sex difference. Further research is needed to identify the reasons why women have poorer outcomes in order to design interventions aimed at reducing stroke disability in women.

Abstract 118: Burden of Blood Pressure-Related Alleles is Associated with Larger Hematoma Volume and Worse Outcome in Intracerebral Hemorrhage

Purpose: Intracerebral hemorrhage (ICH) is the acute manifestation of a progressive disease of the cerebral small vessels. The severity of this disease appears to influence not only risk of ICH, but also the size of the hematoma. As the burden of high blood pressure(BP)-associated alleles is associated with hypertension-related end-organ damage, we sought to determine if this burden influences ICH admission hematoma volume (AHV).

Methods: Prospective study undertaken in 441 ICH patients of European ancestry (210 deep and 231 lobar intracranial hematomas). Forty-three single-nucleotide polymorphisms (SNPs) known to be associated with high BP were genotyped in Illumina610-Quad. Single-SNP association analyses with AHV were performed using linear regression. Subsequently, a genetic risk score was calculated as the sum of the products generated by multiplying, at each of the 43 loci, the number risk alleles times the reported effect of that allele on BP. The score was utilized as the independent variable of univariate and multivariate regression models for 2 outcomes: AHV and poor clinical outcome (modified Rankin Scale 3-6). Principal components analysis was utilized to account for population structure.

Results: Individually assessed, no single SNP was associated with AHV. In univariate linear regression, the genetic risk score was associated with AHV in all (deep and lobar) and deep locations (Figure 1), but not in lobar hemorrhages.

In multivariate regression analyses, each additional standard deviation of the genetic risk score increased mean deep AHV by 21% (or 2.7-milliliter increase, beta=0.21, standard error=0.08, p=0.01) and risk poor clinical outcome by 55% (odds ratio=1.55, 95% confidence interval 1.05-2.28, p=0.03). No significant associations were observed when considering all (deep and lobar) and lobar hemorrhages.

Conclusion: In deep ICH, increasing numbers of high BP-related alleles are associated with larger AHV and poor clinical outcome.

Abstract WP401: Influence of Hospital-Level Practices on Readmission after Ischemic Stroke

Introduction: The Center for Medicare and Medicaid Services intends to publicly report hospital-level readmission rates after ischemic stroke to enable comparisons of hospital quality. The influence of hospitals and hospital-level practices on readmission rates is unknown.

Methods: Adult subjects were entered into this cohort study when hospitalized for ischemic stroke (principal ICD-9-CM 433.x1, 434.x1, 436) in 6 states from 2003-2009 from the State Inpatient Databases. The primary outcome was any non-procedural readmission within 30 days. 26 hospital level practices of interest (utilization of diagnostic testing, procedures, ICU, tPA, and therapeutic modalities) were identified using a combination of ICD-9 procedure codes, diagnosis-related groups (DRGs) and Health Cost and Utilization Project utilization flags. Multilevel logistic regression was used to estimate the association between mean hospital-level practices and readmission after accounting for demographics, vascular risk factors, comorbidities, socioeconomic status and whether a practice was implemented in an individual patient.

Results: Hospitals accounted for 3.7% of the variance in the probability of readmission, intraclass correlation coefficient 0.037 (95% CI 0.031-0.043). Only three practices were associated with readmission: higher use of occupational therapy and acceptance of transfers were associated with lower readmission rates, while higher use of hospice was associated with higher readmission rates. (Table)

Conclusions: Hospitals are responsible for a small proportion of readmission variance. These findings suggest ways that readmission rates may be reduced and illustrate potential susceptibility of a publicly-reported readmission measure to manipulation.

Burden of blood pressure-related alleles is associated with larger hematoma volume and worse outcome in intracerebral hemorrhage

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) is the acute manifestation of a progressive disease of the cerebral small vessels. The severity of this disease seems to influence not only risk of ICH but also the size of the hematoma. As the burden of high blood pressure-related alleles is associated with both hypertension-related end-organ damage and risk of ICH, we sought to determine whether this burden influences ICH baseline hematoma volume.

METHODS

Prospective study in subjects of European descent with supratentorial ICH who underwent genome-wide genotyping. Forty-two single nucleotide polymorphisms associated with high blood pressure were identified from a publicly available database. A genetic risk score was constructed based on these single nucleotide polymorphisms. The score was used as the independent variable in univariate and multivariate regression models for admission ICH volume and poor clinical outcome (modified Rankin Scale, 3-6).

RESULTS

A total of 323 ICH cases were enrolled in the study (135 deep and 188 lobar intracranial hematomas). The blood pressure-based genetic risk score was associated with both baseline hematoma volume and poor clinical outcome specifically in deep ICH. In multivariate regression analyses, each additional SD of the score increased mean deep ICH volume by 28% (or 2.7 mL increase; β=0.28; SE=0.11; P=0.009) and risk of poor clinical outcome by 71% (odds ratio, 1.71; 95% confidence interval, 1.05-2.80; P=0.03).

CONCLUSIONS

Increasing numbers of high blood pressure-related alleles are associated with mean baseline hematoma volume and poor clinical outcome in ICH. These findings suggest that the small vessel vasculopathy responsible for the occurrence of the hemorrhage also influences its volume.

An emergency department intervention to increase warfarin use for atrial fibrillation

BACKGROUND

Emergency department (ED) encounters represent lost opportunities to facilitate anticoagulation for stroke prevention in atrial fibrillation (AF). However, screening of warfarin eligibility in the ED may not be feasible. We evaluated whether a practical quality improvement initiative increased postdischarge warfarin use in ED patients with AF.

METHODS

This quasiexperimental study was conducted in a single academic health system. Eligible subjects were consecutive patients with AF identified by electrocardiogram during an ED evaluation who were discharged from the ED or the subsequent hospitalization off warfarin. The study consisted of data collection during 2 time periods: (1) preintervention (October 2009 to April 2010), serving as a baseline, and (2) intervention (June 2010 to December 2010). The intervention consisted of a mailing to the subjects and their primary care physicians. The primary outcome was the proportion of subjects taking warfarin 1 month after ED presentation. Differences between the proportion of preintervention and intervention subjects taking warfarin and warfarin or aspirin were compared with Chi-square tests.

RESULTS

At 1 month, 111 of 204 (55%) of the eligible preintervention and 90 of 160 (56%) of the eligible intervention group patients participated. There was no difference between the preintervention and intervention groups in the proportion of subjects taking warfarin at 1 month (12% v 9%; P = .54) or the proportion of subjects taking either aspirin or warfarin at 1 month (72% v 75%; P = .59).

CONCLUSIONS

This practical stroke prevention quality improvement initiative was not associated with an increase in warfarin use among ED patients with AF.

Use of BPPV processes in emergency department dizziness presentations: a population-based study

OBJECTIVE

A common cause of dizziness, benign paroxysmal positional vertigo (BPPV), is effectively diagnosed and cured with the Dix-Hallpike test (DHT) and the canalith repositioning maneuver (CRM). We aimed to describe the use of these processes in emergency departments (EDs), assess for trends in use over time, and determine provider level variability in use.

STUDY DESIGN

Prospective population-based surveillance study.

SETTING

Emergency departments in Nueces County, Texas, from January 15, 2008, to January 14, 2011.

SUBJECTS AND METHODS

Adult patients discharged from EDs with dizziness, vertigo, or imbalance documented at triage. Clinical information was abstracted from source documents. A hierarchical logistic regression model adjusting for patient and provider characteristics was used to estimate trends in DHT use and provider-level variability.

RESULTS

A total of 3522 visits for dizziness were identified. A DHT was documented in 137 visits (3.9%). A CRM was documented in 8 visits (0.2%). Among patients diagnosed with BPPV, a DHT was documented in only 21.8% (34 of 156) and a CRM in 3.9% (6 of 156). In the hierarchical model (c-statistic = 0.93), DHT was less likely to be used over time (odds ratio, 0.97; 95% confidence interval, 0.95-0.99), and the provider level explained 50% (intraclass correlation coefficient, 0.50) of the variance in the probability of DHT use.

CONCLUSION

Benign paroxysmal positional vertigo is seldom examined for and, when diagnosed, infrequently treated in this ED population. Use of the DHT is decreasing over time and varies substantially by provider. Implementation research focused on BPPV care may be an opportunity to optimize management in ED dizziness presentations.