Revisiting the NIH Stroke Scale as a screening tool for proximal vessel occlusion: can advanced imaging be targeted in acute stroke?

BACKGROUND AND PURPOSE: Most patients with stroke-like symptoms screened by advanced imaging for proximal occlusion will not have a thrombus accessible by neurointerventional techniques. Development of a sensitive clinical scoring system for rapidly identifying patients with an emergent large vessel occlusion could help target limited resources and reduce exposure to unnecessary imaging. METHODS: This historical cohort study included patients who underwent non-contrast CT and CT angiography in the emergency department for stroke-like symptoms. NIH Stroke Scale (NIHSS) criteria were extended to include resolved symptoms and dichotomized as present or absent. Combinations of NIHSS criteria were considered as tests for proximal occlusion. RESULTS: Proximal cerebral vascular occlusion was present in 19.2% (100/522) of the population and, of these, 13% (13/100) had an NIHSS score of 0. The presence on examination or history of diminished consciousness with inability to answer questions, leg weakness, dysarthria, or gaze deviation had 96% sensitivity and 39% specificity for proximal occlusion. If implemented in this population, the use of CT angiography would have been decreased by 32.4% (169/522 patients) while missing 0.76% with proximal occlusions (4/522). Half of those missed (2/4) would have been identified as large vessel infarcts on non-contrast CT, while the remainder (2/4) were transient ischemic attacks associated with carotid stenosis. CONCLUSIONS: In this cohort, specific NIHSS criteria were highly sensitive for emergent large vessel occlusion and, if validated, may allow for clinical screening prior to advanced imaging with CT angiography.

A TWO-STATE MIXED HIDDEN MARKOV MODEL FOR RISKY TEENAGE DRIVING BEHAVIOR.

This paper proposes a joint model for longitudinal binary and count outcomes. We apply the model to a unique longitudinal study of teen driving where risky driving behavior and the occurrence of crashes or near crashes are measured prospectively over the first 18 months of licensure. Of scientific interest is relating the two processes and predicting crash and near crash outcomes. We propose a two-state mixed hidden Markov model whereby the hidden state characterizes the mean for the joint longitudinal crash/near crash outcomes and elevated g-force events which are a proxy for risky driving. Heterogeneity is introduced in both the conditional model for the count outcomes and the hidden process using a shared random effect. An estimation procedure is presented using the forward-backward algorithm along with adaptive Gaussian quadrature to perform numerical integration. The estimation procedure readily yields hidden state probabilities as well as providing for a broad class of predictors.

Gender differences in college leisure time physical activity: application of the theory of planned behavior and integrated behavioral model.

OBJECTIVE: National data consistently report that males participate in leisure time physical activity (LTPA) at higher rates than females. This study expanded previous research to examine gender differences in LTPA of college students using the theory of planned behavior (TPB) by including 2 additional constructs, descriptive norm and self-efficacy, from the integrated behavioral model. PARTICIPANTS: Participants were college students (N = 621) from a large public university in the southeastern United States. METHODS: A self-report, classroom-based assessment with validated and reliable measures of LTPA, TPB constructs, descriptive norm, self-efficacy, and demographics was conducted in fall 2009. RESULTS: Regression analyses revealed attitude (ß = .119), intention (ß = .438), self-efficacy (ß = .166), body mass index (BMI) (ß = -.084), and sports participation (ß = .081) as significantly associated with LTPA for females (R (2) = .425, p < .001), whereas intention (ß = .371) was significant for males (R (2) = .202, p < .001). CONCLUSIONS: Practitioners should consider tailoring promotional materials to address these gender differences in efforts to increase LTPA participation among college students.

Ordinal latent variable models and their application in the study of newly licensed teenage drivers.

In a unique longitudinal study of teen driving, risky driving behavior and the occurrence of crashes or near crashes are measured prospectively over the first 18 months of licensure. Of scientific interest is relating the two processes and developing a predictor of crashes from previous risky driving behavior. In this work, we propose two latent class models for relating risky driving behavior to the occurrence of a crash or near crash event. The first approach models the binary longitudinal crash/near crash outcome using a binary latent variable which depends on risky driving covariates and previous outcomes. A random effects model introduces heterogeneity among subjects in modeling the mean value of the latent state. The second approach extends the first model to the ordinal case where the latent state is composed of K ordinal classes. Additionally, we discuss an alternate hidden Markov model formulation. Estimation is performed using the expectation-maximization (EM) algorithm and Monte Carlo EM. We illustrate the importance of using these latent class modeling approaches through the analysis of the teen driving behavior.

Do elevated gravitational-force events while driving predict crashes and near crashes?

The purpose of this research was to determine the extent to which elevated gravitational-force event rates predict crashes and near crashes. Accelerometers, global positioning systems, cameras, and other technology were installed in vehicles driven by 42 newly licensed Virginia teenage drivers for a period of 18 months between 2006 and 2009. Elevated gravitational force and crash and near-crash events were identified, and rates per miles driven were calculated. (One mile = 1.6 km.) The correlation between crashes and near crashes and elevated gravitational-force event rates was 0.60. Analyses were done by using generalized estimating equations with logistic regression. Higher elevated gravitational-force event rates in the past month substantially increased the risk of a crash in the subsequent month (odds ratio = 1.07, 95% confidence interval: 1.02, 1.12). Although the difference in this relation did not vary significantly by time, it was highest in the first 6 months compared with the second and third 6-month periods. With a receiver operating characteristic curve, the risk models showed relatively high predictive accuracy with an area under the curve of 0.76. The authors conclude that elevated gravitational-force event rates can be used to assess risk and to show high predictive accuracy of a near-future crash.

Bacterial enteropathogens associated with diarrhea in a rural population of Haiti.

PURPOSE: Diarrheal disease is one of the leading causes of morbidity in developing countries. To further understand the epidemiology of diarrheal disease among a rural population surrounding Robillard, Haiti, fecal swabs from patients with diarrhea were screened for the presence of enteropathogenic bacteria. PATIENTS AND METHODS: Fecal swabs were collected from 34 patients with signs and symptoms of diarrhea and stored in BBL™ Cary-Blair transport medium (Becton, Dickinson and Company, Sparks, MD) until transit to the USA. Swab material was inoculated on to different enrichment and selective agars for incubation. Fermenting and nonfermenting bacteria that grew on the enteric selection media were identified by the BBL™ Crystal™ Enteric/Nonferementing Identification system (Becton, Dickinson and Company). Organisms identified as Escherichia coli were further screened for the presence of virulence factors by polymerase chain reaction (PCR). RESULTS: Of 34 patients, no Campylobacter, Shigella, Salmonella, or Vibrio spp. were isolated from swabs transported to the USA for culture. Of 73 E. coli isolates cultured from the swabs, one enteropathogenic strain of E. coli was identified by multiplex PCR. Escherichia fergusonii and Cronobacter sakazakii, both potential gastrointestinal pathogens, were also isolated from patient stools. CONCLUSION: This study was undertaken to determine if bacterial enteropathogens could be detected in the stools of patients suffering from diarrhea or dysentery and, in the absence of sufficient facilities, rectal swabs could be transported to the USA for culture. Although several genera of overt enteropathogens were not detected, one enteropathogenic E. coli and other pathogenic enterobacteriaceae were successfully cultured and identified.