Recent advances in stroke rehabilitation 2006.
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Biomedical subjects
Publications and source records attributed to Lalit Kalra.
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BACKGROUND: Although metabolic syndrome affects vascular function, the impact of individual impairments and their clustering is unclear. OBJECTIVE: To assess the vascular impact of metabolic impairments before they reach treatment thresholds in different ethnic groups. METHODS: Metabolic variables, inflammatory markers, endothelium dependent vasodilatation (EDV) and carotid intima media thickness (CIMT) were measured in population samples of 82 Caucasians and 78 matched Afro-Caribbeans with no vascular disease. Insulin resistance was assessed using homeostasis model assessment (HOMA-IR). EDV was measured as the change in the height of the inflection point of the digital volume pulse following intravenous infusion of 5 mcg/min of albuterol (DeltaRIDeltaLB). Regression models were used to investigate the independent effects of metabolic impairment clusters and their interaction with ethnicity on EDV and CIMT. RESULTS: HOMA-IR (2.4-3.8, p < 0.0001), IL-6 levels (1.1-2.8 pg/mL, p = 0.02) and CIMT (0.71-0.83 mm, p = 0.009) increased whereas in DeltaRIBASELINE (77.6-72.9 percentage points, p < 0.0001) and DeltaRIDeltaLB (15.5-7.1 percentage points, p < 0.0001) decreased with the number of metabolic impairments present. DeltaRIDeltaLB decreased by 1.6 (95% CI 0.2-3.7) percentage points and CIMT increased by 0.06 (95% CI 0.02-0.10) mm for each metabolic impairment present after adjusting for age, gender, ethnicity and HOMA-IR. There were significant interactions between Afro-Caribbean ethnicity and metabolic impairments for IL-6 (p = 0.037) and DeltaRIDeltaLB (p = 0.002). CONCLUSIONS: Clustering of metabolic impairments is associated with inflammatory activation, impaired EDV and increased CIMT even before reaching treatment thresholds for individual impairments. This effect was more marked in Afro-Caribbean subjects.
BACKGROUND AND PURPOSE: Desaturation during swallowing may help to identify aspiration in stroke patients. This study investigated pulse oximetry, bedside swallowing assessment (BSA), and videofluoroscopy as tests for detecting aspiration after stroke. METHODS: Swallowing was assessed in 189 stroke patients (mean+/-SD age, 70.9+/-12.3 years) within 5 days of symptom onset with a modified BSA (water replaced by radio-opaque contrast agent, followed by chest radiography to detect aspiration). Simultaneous pulse oximetry recorded the greatest desaturation from baseline for 10 minutes from modified BSA onset. Videofluoroscopy was undertaken in 54 (28%) patients. RESULTS: Modified BSA showed a safe swallow in 98 (51.9%), unsafe swallow in 85 (45.0%), and silent aspiration in 6 (3.2%) patients. During swallowing, desaturation by >2% occurred in 27 (27.6%) and by >5% in 3 (3.1%) of the 98 safe-swallow patients on modified BSA. Of the 85 unsafe-swallow patients, only 28 (32.9%) desaturated by >2% and 6 (7.1%) by >5%. Desaturation did not occur in any of the 6 silent aspirators. With the modified BSA to detect aspiration, sensitivity and specificity, respectively, were 0.31 and 0.72 for desaturation >2% and 0.07 and 0.97 for desaturation >5%. By videofluoroscopy, sensitivity and specificity for detecting aspiration were 0.47 and 0.72 for modified BSA, 0.33 and 0.62 for desaturation >2%, and 0.13 and 0.95 for desaturation >5%. Combining a failed modified BSA with desaturation >2% or >5% did not significantly improve predictive values. CONCLUSIONS: Modified BSA and pulse oximetry during swallowing, whether alone or in combination, showed inadequate sensitivity, specificity, and predictive values for detection of aspiration compared with videofluoroscopy in stroke patients.
OBJECTIVES: This study sought to compare vascular reactivity and carotid intima media thickness (CIMT) between Afro-Caribbean people in the United Kingdom (UK) and the West Indies and Afro-Caribbean and Caucasian people in the UK. BACKGROUND: Attenuated vascular reactivity and increased CIMT in black patients is seen as evidence for predisposition to vascular disease, but no comparisons exist between Afro-Caribbean people in different settings, which can provide insight into non-inherited determinants of increased ethnic susceptibility. METHODS: A representative community sample of 81 healthy Afro-Caribbean people and 101 Caucasian people in the UK was compared with 197 matched Afro-Caribbean people in Jamaica. Small vessel reactivity was assessed by measuring the absolute change from baseline in the reflection index (RI) of the digital volume pulse during intravenous infusion of albuterol (5 microg/min, DeltaRI(ALB)) and glyceryl trinitrate (5 microg/min, DeltaRI(GTN)). The CIMT was measured ultrasonographically in the distal 1 cm of the common carotid artery. RESULTS: Mean DeltaRI(ALB) was 4.2 percentage points (95% confidence interval [CI], 2.3 to 6.1, p < 0.001) lower in UK Afro-Caribbean people compared with Jamaican Afro-Caribbean people and 2.6 percentage points (95% CI, 0.4 to 4.7, p = 0.02) lower compared with Caucasian people, after adjusting for vascular risk profile. Adjusted mean CIMT of UK Afro-Caribbean people was 0.13 mm (95% CI, 0.08 to 0.17, p < 0.001) greater compared with Jamaican Afro-Caribbean people and 0.05 mm (95% CI, 0.01 to 0.10, p = 0.02) greater compared with Caucasian people. CONCLUSIONS: Healthy UK Afro-Caribbean people have greater and Jamaican Afro-Caribbean people have less impairment of vascular reactivity and intima media thickness compared with UK Caucasian people, suggesting that potentially modifiable environmental interactions may contribute to excess vascular disease in Afro-Caribbean people.
Prism adaptation can ameliorate some symptoms of left spatial neglect after right-hemisphere stroke. The mechanisms behind this remain unclear. Prism therapy may increase exploration towards the contralesional side, yet without improving perceptual awareness, as apparently for the left side of chimeric face stimuli (Ferber et al. 2003). However, other prism studies suggest that perceptual awareness might be improved (e.g., Maravita et al., 2003). We tested the impact of prism therapy on visual awareness for the left side of chimeric objects as well as chimeric faces, in three neglect patients. Prism therapy dramatically improved awareness for the identity of the left side of chimeric non-face objects, but had no effect on judging expressions for chimeric faces. The latter may thus be unique in showing no prism benefit.
OBJECTIVE: To review systematically and synthesize quantitatively the evidence from completed randomized, controlled trials of blood pressure reduction on cognitive performance. METHODS: MEDLINE, EMBASE and Cochrane databases were searched to identify randomized, controlled trials that measured the effect of blood pressure reduction on cognitive performance. Additional studies were identified by searching bibliographies of retrieved articles and contacting experts in the field. Data were extracted on study quality, blood pressure, performance on cognitive function tests, antihypertensive treatment regimens and the duration of treatment. Studies were reviewed and abstracted independently by two trained researchers. RESULTS: Sixteen studies with 19 501 subjects were identified. Modest reductions in blood pressure (< 5/3 mmHg) in 13 860 subjects were associated with improvements in Mini Mental State Examination score [weighted mean difference (WMD) = 0.19; 95% confidence interval (CI) = 0.19-0.19] and performance on immediate (WMD = 0.62; 95% CI = 0.21-1.02) and delayed (WMD = 0.67; 95% CI = 0.23-1.11) logical memory tasks. However, studies in 2380 subjects that included tests of perceptual processing and learning capacity (trail making test-A, paired associated learning test) showed impaired performance (WMD = -1.12 s; 95% CI = -1.22 to -1.02 and WMD = -0.04; 95% CI = -0.04 to -0.04) on these tests. CONCLUSION: Blood pressure lowering may have a heterogeneous effect on different aspects of cognitive function. Future studies with specific cognitive end-points are needed for greater clarity to guide practice.
BACKGROUND AND PURPOSE: A large proportion of disabled stroke survivors live at home and are supported by informal caregivers. Identification of determinants of caregiver burden will help to target caregiver interventions. METHODS: Data on patient, caregiver, and health and social support characteristics were collected prospectively over 1 year in 232 stroke survivors in a randomized trial of caregiver training. The contribution of these variables to caregiver burden score (CBS) and quality of life (QOL) measures at 3 months and 1 year was analyzed using regression models. RESULTS: Stroke patients had a mean age of 74+/-11 years, and 120 (52%) were men. The mean age of caregivers was 65.7+/-12.5 years, 149 (64%) were females, and 116 (50%) had received caregiver training. The mean CBS was 48+/-13 and 38+/-11 (score range of bad to good 88 to 22) and QOL score was 75+/-16 and 75+/-15 (score range of bad to good 0 to 100) at 3 months and 1 year, respectively. CBS and QOL correlated with each other and with patient (age, dependency, and mood), caregiver (age, gender, mood, and training), and support (social services and family networks) variables. Of these, only patient and caregiver emotional status, caregiver age and gender, and participation in caregiver training were independent predictors of either outcome at 3 months. Patient dependency and family support were additional independent predictors at 1 year. Social services support predicted institutionalization but not caregiver outcomes. CONCLUSIONS: Advancing age and anxiety in patients and caregivers, high dependency, and poor family support identify caregivers at risk of adverse outcomes, which may be reduced by caregiver training.
OBJECTIVE: Small vessel disease is more common in Afro-Caribbeans than Caucasians. We investigated underlying differences in metabolic, inflammatory, and vascular responses that may predispose Afro-Caribbeans to small vessel pathology. METHODS AND RESULTS: Seventy-eight Afro-Caribbeans aged 35-75 years, with no vascular disease or medications, were compared with 82 matched Caucasians for metabolic variables, fasting insulin, interleukin 6, tumor necrosis factor (TNF) alpha, and cytoplasmic repressor protein levels. Carotid intima media thickness (CIMT) was measured ultrasonographically. Small vessel function was assessed by measuring the absolute change from baseline in the reflectance index (RI) of the digital volume pulse during IV infusion of albuterol (5 microg/min, DeltaRIALB) and glyceryl tri nitrate (5 microg/min, DeltaRIGTN). Large artery elasticity was measured as the stiffness index (SI) and derived from the time to pulse wave reflection adjusted for subject height. Afro-Caribbeans had significantly higher diastolic blood pressure (80.3 versus 77.6 mm Hg; P=0.033), fasting insulin (14.0 versus 10.6 microU/mL; P=0.026), TNF-alpha (6.7 versus 4.3; pg/mL; P=0.001), and interleukin 6 (2.3 versus 1.5 pg/mL; P=0.036) levels compared with Caucasians. CIMT was greater (0.81+/-0.20 versus 0.75+/-0.18 mm; P=0.02) and small vessel reactivity attenuated (mean DeltaRIALB 6.8+/-8.0% versus 12.3+/-8.%; P<0.0001) in Afro-Caribbeans, but their large artery elasticity (mean index of large artery stiffness 9.9 versus 9.7 m/s; P=0.48) was comparable with Caucasians. CIMT was independently associated with an index of large artery stiffness (beta=0.03; P=0.002) in Caucasians but not in Afro-Caribbeans. There were independent relationships among Afro-Caribbean ethnicity, TNF-alpha, and insulin levels. CONCLUSIONS: Selective impairment of small artery function may contribute to excess small vessel disease in Afro-Caribbeans.
The importance of lowering blood pressure (BP) in hypertensive subjects is well-known and recent studies suggest that lowering of BP in patients who may already be in the normotensive range further reduces the risk of vascular events, particularly stroke. Epidemiological data have also shown that lower BP and antihypertensive treatment may be associated with cognitive impairment once cerebrovascular disease is established. However, the relationship between hypertension and cerebrovascular disease is more complex than suggested by epidemiological or intervention studies. Cerebral imaging studies have shown that cerebral blood flow (CBF) is reduced in areas of small-vessel disease (SVD) and the degree of hypoperfusion correlates with disease severity. Furthermore, impaired neuropsychological performance has been found to correlate with cerebral hypoperfusion in patients with established SVD. These findings raise questions surrounding the desirability of lowering of BP beyond a certain level in such patients. It is conceivable that indiscriminate BP reduction may compromise cerebral perfusion and function in these patients, increasing the risk of cognitive decline and cerebrovascular disease progression. Randomized clinical trials addressing the relationship between antihypertensive treatment and vascular cognitive impairment are lacking. Further studies are therefore needed to assess the cognitive consequences of BP reduction in people with established cerebrovascular disease. This will help to direct appropriate protective strategies and treatments in a vulnerable group of people, many of whom have hypertension and cerebrovascular disease at the same time.
BACKGROUND AND PURPOSE: Stroke outcomes in patients with atrial fibrillation (AF) tend to be worse than those in patients without AF. The objective of this study was to evaluate whether the cost benefits of anticoagulation for stroke prevention in AF may currently be underestimated by existing economic models that do not distinguish between different stroke outcomes. METHODS: A literature review was conducted in 3 areas: (1) studies comparing stroke outcomes in AF and non-AF patients; (2) studies providing long-term cost of stroke estimates; and (3) studies modeling the cost-effectiveness of anticoagulation with a vitamin K antagonist (eg, warfarin) in AF patients. RESULTS: There is considerable evidence that stroke in AF patients has a worse outcome than in patients without AF, including higher mortality, severity, and recurrence rates, and greater functional impairment and dependency. Estimates of the long-term cost of stroke of different severities were between US 24,991 dollars for a mild stroke over 5 years and US 142,251 dollars for a major ischemic stroke over a lifetime (2004 prices). The cost of a severe ischemic stroke may typically be 3-times that of mild stroke. However, cost-effectiveness models for anticoagulation in patients with AF have used average (not AF-specific) cost-of-stroke data, and most have used stroke severity distributions derived from clinical trials, which may differ from those in clinical practice. CONCLUSIONS: Existing economic models underestimate the cost benefits of anticoagulation for stroke prevention because they do not adjust for poorer outcomes associated with cardioembolic strokes.
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The goal of this study was to compare the diagnostic value of an absent gag reflex in acute stroke patients with the bedside swallowing assessment (BSA) and assess its relationship to outcomes. Two hundred forty-two acute stroke patients had their gag reflex tested and a BSA performed. Numbers needing nasogastric or gastrostomy tube insertion were noted, also their discharge destination, discharge Barthel Index, and mortality. The mean age of the subjects was 76.5+/-10.2 years; 37.6% were male; 41.7% of the patients were dysphagic on BSA; 18.2% had an absent gag. Dysphagia was present in 88.6% of the patients with an absent gag and in 31.3% of those with an intact gag. The gag reflex was absent in 38.6% of dysphagic and 3.5% of nondysphagic patients. Comparing an absent gag against the criterion of the BSA, its specificity was 0.96, sensitivity 0.39, positive predictive value 0.89, and negative predictive value 0.69. Regression analyses found that an intact gag gave an Odds Ratio [CI] of 0.23 [0.06-0.91] for gastrostomy feeding but did not predict other outcomes. We conclude that the gag reflex is as specific as but less sensitive than the BSA in detecting dysphagia in acute stroke patients. An intact gag may be protective against longer-term swallowing problems and the need for enteral feeding.
Although clinically evident aspiration is common in subjects with dysphagia, a significant proportion may aspirate silently, i.e., without any outward signs of swallowing difficulty. This article reviews the literature on the prevalence, etiology, and prognostic significance of silent aspiration. An electronic database search was performed using silent aspiration, aspiration, dysphagia, and stroke as search terms, together with hand-searching of articles. Silent aspiration has been described in many conditions and subgroups of patients (including normal individuals), using a number of detection methods, making comparisons a challenge. The best data are for acute stroke, in which 2%-25% of patients may aspirate silently. Mechanisms associated with silent aspiration may include central or local weakness/incoordination of the pharyngeal musculature, reduced laryngopharyngeal sensation, impaired ability to produce a reflexive cough, and low substance P or dopamine levels. In terms of prognosis, silent aspiration has been associated with increased morbidity and mortality in many but not all studies. However, some degree of silent aspiration at night may be normal in healthy individuals. The phenomenon of silent aspiration is poorly understood and further research is needed to improve methods of detection and thereby better define its prevalence and prognostic significance.
BACKGROUND: Informal care givers support disabled stroke patients at home but receive little training for the caregiving role. OBJECTIVE: To evaluate the effectiveness of training care givers in reducing burden of stroke in patients and their care givers. DESIGN: A single, blind, randomised controlled trial. SETTING: Stroke rehabilitation unit. SUBJECTS: 300 stroke patients and their care givers. INTERVENTIONS: Training care givers in basic nursing and facilitation of personal care techniques. MAIN OUTCOME MEASURES: Cost to health and social services, caregiving burden, patients' and care givers' functional status (Barthel index, Frenchay activities index), psychological state (hospital anxiety and depression score), quality of life (EuroQol visual analogue scale) and patients' institutionalisation or mortality at one year. RESULTS: Patients were comparable for age (median 76 years; interquartile range 70-82 years), sex (53% men), and severity of stroke (median Barthel index 8; interquartile range 4-12). The costs of care over one year for patients whose care givers had received training were significantly lower (10,133 pounds sterling v 13,794 pounds sterling (18,087 dollars v 24,619 dollars; 15,204 euros v 20,697 euros); P = 0.001). Trained care givers experienced less caregiving burden (care giver burden score 32 v 41; P = 0.0001), anxiety (anxiety score 3 v 4; P = 0.0001) or depression (depression score 2 v 3; P = 0.0001) and had a higher quality of life (EuroQol score 80 v 70; P = 0.001). Patients' mortality, institutionalisation, and disability were not influenced by caregiver training. However, patients reported less anxiety (3 v 4.5; P < 0.0001) and depression (3 v 4; P < 0.0001) and better quality of life (65 v 60; P = 0.009) in the caregiver training group. CONCLUSION: Training care givers during patients' rehabilitation reduced costs and caregiver burden while improving psychosocial outcomes in care givers and patients at one year.
BACKGROUND: Training care givers reduces their burden and improves psychosocial outcomes in care givers and patients at one year. However, the cost effectiveness of this approach has not been investigated. OBJECTIVE: To evaluate the cost effectiveness of caregiver training by examining health and social care costs, informal care costs, and quality adjusted life years in care givers. DESIGN: A single, blind, randomised controlled trial. SETTING: Stroke rehabilitation unit. SUBJECTS: 300 stroke patients and their care givers. INTERVENTIONS: Caregiver training in basic nursing and facilitation of personal care techniques compared with no care giver training. MAIN OUTCOME MEASURES: Health and social care costs, informal care costs, and quality adjusted life years in care givers over one year after stroke. RESULTS: Total health and social care costs over one year for patients whose care givers received training were significantly lower (mean difference -4043 pounds sterling (7249 dollars; 6072 euros), 95% confidence interval -6544 pounds sterling to -595 pounds sterling). Inclusion of informal care costs, which were similar between the two groups, did not alter this conclusion. The cost difference was largely due to differences in length of hospital stay. The EQ-5D did not detect changes in quality adjusted life years in care givers. CONCLUSION: Compared with no training, caregiver training during rehabilitation of patients reduced costs of care while improving overall quality of life in care givers at one year.
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BACKGROUND AND PURPOSE: Although stroke units reduce mortality and institutionalization, their comparative cost-effectiveness is unknown. METHODS: Healthcare, social services, and informal care costs were compared for 447 acute stroke patients randomly assigned to stroke unit, stroke team, or domiciliary stroke care. Prospective and retrospective methods were used to identify resource use over 12 months after stroke onset. Cost-effectiveness and cost-utility analyses were undertaken. RESULTS: Mean healthcare and social care costs over 12 months were 11 450 pounds sterling for stroke unit, 9527 pounds sterling for stroke team, and 6840 pounds sterling for domiciliary care. More than half the costs were for the initial episode of care. Institutionalization was a large proportion of follow-up costs. Inclusion of informal care increased costs considerably. When informal care was excluded, the incremental cost-effectiveness ratio per percentage point in deaths or institutionalizations avoided in the first year was 496 pounds sterling for the stroke unit over domiciliary care; incremental cost per quality-adjusted life year quality-adjusted life year gained was 64 097 pounds sterling between these 2 groups. The stroke team was dominated by domiciliary care. CONCLUSIONS: Cost perspectives, especially those related to long-term and informal care, are important when stroke services are evaluated. Improved health outcomes in the stroke unit come at a higher cost.
BACKGROUND AND PURPOSE: The role of hypercoagulable states in the pathogenesis of ischemic stroke in black subjects is not known, and data on normal reference ranges in black populations are lacking. This study estimated ethnic-specific reference ranges in a community population to determine the prevalence of thrombophilic states in a multiethnic stroke population. METHODS: Free protein S, protein C, antithrombin III, activated protein C resistance, IgG anticardiolipin antibodies, and lupus anticoagulant were determined in 130 consecutive ischemic stroke cases < or =65 years of age (50 black Caribbeans, 30 black Africans, 50 whites) and 130 community controls. RESULTS: Black African controls had significantly lower protein S (P<0.001) and protein C (P=0.049) and a trend toward lower antithrombin III (P=0.056) levels compared with white controls. Black Caribbean and African controls had higher diluted Russell's viper venom time ratios compared with whites (P=0.001, P<0.001). Using ethnic-specific reference ranges, 8 controls (6.3%) and 11 cases (8.5%) had thrombophilia abnormalities (odds ratio [OR], 1.39; 95% confidence interval [CI], 0.54 to 3.57; P=0.50). ORs were 0.96 (95% CI, 0.18 to 4.99; P=0.96) for whites, 1.57 (95% CI, 0.41 to 5.94; P=0.51) for black Caribbeans, and 2.07 (95% CI, 0.18 to 24.2; P=0.95) for black Africans. CONCLUSIONS: Failure to account for ethnic differences in the normal reference ranges for thrombophilia markers may lead to inappropriate diagnosis and investigation of hypercoagulable states in black individuals. Protein S and protein C deficiencies and lupus anticoagulant may contribute to stroke risk in a minority of black cases, but they are unlikely to be major contributors to the excess stroke risk seen in young individuals of African and African-Caribbean descent.