Martin Dennis

The University of Edinburgh, Edinburgh, Scotland, United Kingdom

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Publications (251)2128.25 Total impact

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    ABSTRACT: Anxiety is common and persistent after stroke, and is associated with a poorer quality of life. Guidelines from numerous countries, including the United Kingdom, recommend screening for poststroke emotional problems. Anxiety is a priority for the National Institute for Health and Care Excellence, stroke charities, and stroke survivors in the United Kingdom. Yet there is little evidence to guide the management of anxiety after stroke. New evidence-based interventions are needed to improve the care of poststroke anxiety. © 2015 World Stroke Organization.
    International Journal of Stroke 07/2015; 10(5):655-656. DOI:10.1111/ijs.12493 · 4.03 Impact Factor
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    ABSTRACT: Objective The aim of this study was to examine the practicality and accuracy of using an electronic monitoring device as a means of measuring medication adherence in elderly stroke survivors, with emphasis on patients’ experiences. Methods The Medication Event Monitoring System (MEMS), which records date and time of pill-bottle openings, was used to measure adherence to antihypertensive medication in a randomized controlled trial (RCT) of a brief psychological intervention with 58 stroke survivors. Patients were asked to describe and rate their experiences of using the MEMS pill bottle. Results MEMS adherence was related to both pill count and self-reported adherence (Medication Adherence Report Scale). Most patients found the MEMS acceptable and easy to use, although some found it cumbersome and/or experienced difficulties with the cap. Nearly half (48 %) reported at least one instance where MEMS data did not reflect their pill-taking behavior (e.g. taking a tablet out the day before to take on a flight); 55 % of patients indicated that the MEMS helped them remember their medication, suggesting a mere measurement effect. Conclusion Electronic pill monitoring has many flaws, including practical difficulties and data inaccuracies. There was evidence of a measurement effect, indicating that MEMS should be used in both intervention and control arms when used to measure adherence within RCTs. We also observed that the MEMS pill bottle is not suitable for measuring adherence in patients who use their own ‘days of the week’ box for sorting medication, as we found poorer adherence at follow-up in this group. Despite these limitations, we conclude that electronic monitoring presents the best method currently available for objective measurement of adherence, especially where detailed timing information is required. Accuracy may be improved by the concurrent use of other measures (e.g. pill count, self-report).
    Drugs & Therapy Perspectives 05/2015; 31:167-174. DOI:10.1007/s40267-015-0200-6
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    ABSTRACT: Dietary salt intake and hypertension are associated with increased risk of cardiovascular disease including stroke. We aimed to explore the influence of these factors, together with plasma sodium concentration, in cerebral small vessel disease (SVD). In all, 264 patients with nondisabling cortical or lacunar stroke were recruited. Patients were questioned about their salt intake and plasma sodium concentration was measured; brain tissue volume and white-matter hyperintensity (WMH) load were measured using structural magnetic resonance imaging (MRI) while diffusion tensor MRI and dynamic contrast-enhanced MRI were acquired to assess underlying tissue integrity. An index of added salt intake (P=0.021), pulse pressure (P=0.036), and diagnosis of hypertension (P=0.0093) were positively associated with increased WMH, while plasma sodium concentration was associated with brain volume (P=0.019) but not with WMH volume. These results are consistent with previous findings that raised blood pressure is associated with WMH burden and raise the possibility of an independent role for dietary salt in the development of cerebral SVD.Journal of Cerebral Blood Flow & Metabolism advance online publication, 22 April 2015; doi:10.1038/jcbfm.2015.64.
    Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 04/2015; DOI:10.1038/jcbfm.2015.64 · 5.34 Impact Factor
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    ABSTRACT: Dysphagia is common after stroke, so feeding through a nasogastric (NG) tube may be necessary. These tubes are frequently dislodged, causing interruption to feeding and hydration, and potential aspiration of feed or fluids into the lungs. Interventions to prevent this may include taping tubes to the face; the application of hand mittens or bandaging patients' hands; inserting the NG tube into the nostril on the stroke-affected side; and nasal bridles. The aims of this survey were to investigate the management of NG feeding for stroke patients, including current tube confirmation and securing techniques, and associated nurse education. This was part of a three-phased sequential mixed-methods study. This paper reports on the second quantitative phase. A quantitative postal survey, based on initial qualitative findings, was sent to registered nurses (n=528) from the National Stroke Nurses Forum and Scottish Stroke Nurses Forum, in addition to registered nurses working on stroke units within the local health board. The overall response rate was 59% (n=314/528). Tape was the most commonly used method for securing tube position, followed by inserting the tube on the stroke-affected side. Hand mittens were used more frequently than the nasal bridle; bandaging hands was reported once. Taping was considered to be more acceptable and safer than hand mittens or the nasal bridle, but less effective. Training in inserting NG feeding tubes was received by 56% (n=176/314). Methods used for confirming tube position included aspiration and X-ray. Provision of training in confirmation techniques varied. This study shows that the management of NG feeding for dysphagic stroke patients requires standardisation, as does the education for nurses to ensure that this intervention is carried out safely, effectively and acceptably.
    British journal of nursing (Mark Allen Publishing) 03/2015; 24(6):319-25. DOI:10.12968/bjon.2015.24.6.319
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    ABSTRACT: The pathogenesis of poststroke fatigue is unclear. In this prospective study, we explored whether reduced physical activity might contribute to poststroke fatigue or be a consequence of it. Patients with a recent acute stroke were assessed at 1, 6, and 12 months with, Fatigue Assessment Scale (FAS), a fatigue case definition, Hospital Anxiety and Depression Score, sleepiness, quality of life, and accelerometry (ActivPAL). Bivariate analyses determined associations between fatigue and step count at each time point. Multiple linear regression tested whether 1-month step count independently predicted 6- and 12-month FAS. A total of 136 participants (mean age, 72 years; 64% men) attended ≥1 assessment. ActivPAL data were available for 84 (64%), 69 (66%), and 58 (64%) participants at 1, 6, and 12 months, respectively. At 6 and 12 months, a positive fatigue case definition was associated with lower daily step counts (P=0.014 and 0.013, respectively). At 1, 6, and 12 months, higher FAS (more fatigue) was associated with lower step count (P<0.001, 0.01, and 0.007), higher depression (P<0.001), anxiety scores (P<0.001) and sleepiness (P<0.001), and poorer quality of life (P<0.001). Lower daily step count (P<0.002 and 0.006) and greater anxiety (P<0.001 for both) at 1 month independently predicted higher FAS at 6 and 12 months. Lower step counts at 1 month independently predicted greater FAS for ≤12 months. Physical activity might be a therapeutic target for poststroke fatigue. © 2015 American Heart Association, Inc.
    Stroke 02/2015; 46(4). DOI:10.1161/STROKEAHA.114.008079 · 6.02 Impact Factor
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    ABSTRACT: Further research is needed to better identify the methods of evaluating processes and outcomes of stroke care. We investigated whether achieving 4 evidence-based components of a care bundle in a Scotland-wide population with ischemic stroke is associated with 30-day and 6-month outcomes. Using national datasets, we looked at the effect of 4 standards (stroke unit entry on calendar day of admission [day 0] or day following [day 1], aspirin on day 0 or day 1, scan on day 0, and swallow screen recorded on day 0) on mortality and discharge to usual residence, at 30 days and 6 months. Data were corrected for the validated 6 simple variables, admission year, and hospital-level random effects. A total of 36 055 patients were included. Achieving stroke unit admission, swallow screen, and aspirin standards were associated with reduced 30-day mortality (adjusted odds ratio [95% confidence interval]: 0.82 [0.75-0.90], 0.88 [0.77-0.99], and 0.39 [0.35-0.43], respectively). Thirty-day all-cause mortality was higher when fewer standards were achieved, from 0 versus 4 (adjusted odds ratio [95% confidence interval], 2.95 [1.91-4.55]) to 3 versus 4 (adjusted odds ratio [95% confidence interval], 1.21 [1.09-1.34]). This effect persisted at 6 months. When less than the full care bundle was achieved, discharge to usual residence was less likely at 6 months (3 versus 4 standards; adjusted odds ratio [95% confidence interval], 0.91 [0.85-0.98]). Achieving a care bundle for ischemic stroke is associated with reduced mortality at 30 days and 6 months and increased likelihood of discharge to usual residence at 6 months. © 2015 American Heart Association, Inc.
    Stroke 02/2015; 46(4). DOI:10.1161/STROKEAHA.114.007608 · 6.02 Impact Factor
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    ABSTRACT: We compared compliance with standards of acute stroke care between 6 European audits and identified factors associated with delivery of appropriate care. Data were derived from stroke audits in Germany, Poland, Scotland, Catalonia, Sweden, and England/Wales/Northern-Ireland participating within the European Implementation Score (EIS) collaboration. Associations between demographic and clinical characteristics with adherence to predefined quality indicators were investigated by hierarchical logistic regression analyses. In 2007/2008 data from 329 122 patients with stroke were documented. Substantial variations in adherence to quality indicators were found; older age was associated with a lower probability of receiving thrombolytic therapy, anticoagulant therapy, or stroke unit treatment and a higher probability of being tested for dysphagia. Women were less likely to receive anticoagulant or antiplatelet therapy or stroke unit treatment. No major weekend effect was found. Detected variations in performance of acute stroke services were found. Differences in adherence to quality indicators might indicate population subgroups with specific needs for improving care delivery. © 2014 American Heart Association, Inc.
    Stroke 12/2014; 46(2). DOI:10.1161/STROKEAHA.114.007504 · 6.02 Impact Factor
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    ABSTRACT: Background The small vessel disease (SVD) that appears in the brain may be part of a multisystem disorder affecting other vascular beds such as the kidney and retina. Because renal failure is associated with both stroke and white matter hyperintensities we hypothesised that small vessel (lacunar) stroke would be more strongly associated with renal failure than cortical stroke. Therefore, we performed a systematic review and meta-analysis to establish first if lacunar stroke was associated with the renal function, and second, if cerebral small vessel disease seen on the MRI of patients without stroke was more common in patients with renal failure. Methods We searched Medline and EMBASE for studies in adults with cerebral SVD (lacunar stroke or white matter hyper intensities (WMH) on Magnetic Resonance Imaging (MRI)), in which renal function was assessed (estimated glomerular filtration rate (eGFR) or proteinuria). We extracted data on SVD diagnosis, renal function, demographics and comorbidities. We performed two meta-analyses: first, we calculated the odds of renal impairment in lacunar (small vessel) ischaemic stroke compared to other ischaemic stroke subtypes (non-small vessel disease); and second, we calculated the odds of renal impairment in non-stroke individuals with WMH on MRI compared to individuals without WMH. We then performed a sensitivity analysis by excluding studies with certain characteristics and repeating the meta-analysis calculation. Results After screening 11,001 potentially suitable titles, we included 37 papers reporting 32 studies of 20,379 subjects: 15 of stroke patients and 17 of SVD features in non-stroke patients. To diagnose lacunar stroke, 13/15 of the studies used risk factor-based classification (none used diffusion-weighted MRI). 394/1,119 (35%) of patients with lacunar stroke had renal impairment compared with 1,443/4,217 (34%) of patients with non-lacunar stroke, OR 0.88, (95% CI 0.6-1.30). In individuals without stroke the presence of SVD was associated with an increased risk of renal impairment (whether proteinuria or reduced eGFR) OR 2.33 (95% CI 1.80-3.01), when compared to those without SVD. After adjustment for age and hypertension, 15/21 studies still reported a significant association between renal impairment and SVD. Conclusion We found no specific association between renal impairment and lacunar stroke, but we did find that in individuals who had not had a stroke, having more SVD features on imaging was associated with a worse renal function, which remained significant after controlling for hypertension. However, this finding does not exclude a powerful co-associate effect of age or vascular risk factor exposure. Future research should subtype lacunar stroke sensitively and control for major risk factors.
    Cerebrovascular Diseases 12/2014; 39(1):39-52. DOI:10.1159/000369777 · 3.70 Impact Factor
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    ABSTRACT: Background To determine whether the predictions of functional outcome after ischemic stroke made at the bedside using a doctor’s clinical experience were more or less accurate than the predictions made by clinical prediction models (CPMs). Methods and Findings A prospective cohort study of nine hundred and thirty one ischemic stroke patients recruited consecutively at the outpatient, inpatient and emergency departments of the Western General Hospital, Edinburgh between 2002 and 2005. Doctors made informal predictions of six month functional outcome on the Oxford Handicap Scale (OHS). Patients were followed up at six months with a validated postal questionnaire. For each patient we calculated the absolute predicted risk of death or dependence (OHS≥3) using five previously described CPMs. The specificity of a doctor’s informal predictions of OHS≥3 at six months was good 0.96 (95% CI: 0.94 to 0.97) and similar to CPMs (range 0.94 to 0.96); however the sensitivity of both informal clinical predictions 0.44 (95% CI: 0.39 to 0.49) and clinical prediction models (range 0.38 to 0.45) was poor. The prediction of the level of disability after stroke was similar for informal clinical predictions (ordinal c-statistic 0.74 with 95% CI 0.72 to 0.76) and CPMs (range 0.69 to 0.75). No patient or clinician characteristic affected the accuracy of informal predictions, though predictions were more accurate in outpatients. Conclusions CPMs are at least as good as informal clinical predictions in discriminating between good and bad functional outcome after ischemic stroke. The place of these models in clinical practice has yet to be determined.
    PLoS ONE 10/2014; 9(10):e110189. DOI:10.1371/journal.pone.0110189 · 3.53 Impact Factor
  • Rustam Al-Shahi Salman, Martin S Dennis
    Stroke 09/2014; 45(10). DOI:10.1161/STROKEAHA.114.005786 · 6.02 Impact Factor
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    ABSTRACT: In this cross-sectional study, we tested the construct validity of a "total SVD score," which combines individual MRI features of small-vessel disease (SVD) in one measure, by testing associations with vascular risk factors and stroke subtype.
    Neurology 08/2014; 83(14). DOI:10.1212/WNL.0000000000000837 · 8.30 Impact Factor
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    ABSTRACT: Objective: The purpose of the current study was to test theory-based predictions of mediators and moderators of treatment effects of a pilot randomized controlled trial, which aimed to increase adherence to preventive medication in stroke survivors via addressing both automatic (i.e., habitual responses) and reflective (i.e., beliefs and value systems) aspects of medication-taking behavior. Method: Sixty-two stroke survivors were randomly allocated to either an intervention or control group. Intervention participants received a brief 2-session intervention aimed at increasing adherence via (a) helping patients establish better medication-taking routines using implementation intentions plans (automatic), and (b) eliciting and modifying any mistaken patient beliefs regarding medication and/or stroke (reflective). The control group received similar levels of non-medication-related contact. Primary outcome was adherence to antihypertensive medicine measured objectively over 3 months using an electronic pill bottle. Secondary outcome measures included self-reported adherence (including forgetting) and beliefs about medication. Results: Intervention participants had 10% greater adherence on doses taken on schedule (intervention, 97%; control, 87%; 95% CI [0.2, 16.2], p = .048), as well as significantly greater increases in self-reported adherence and reductions in concerns about medication. Treatment effects were mediated by reductions in both forgetting and concerns about medication, and moderated by the presence of preexisting medication-taking routines. Conclusions: Addressing both automatic and reflective aspects of behavior via helping stroke survivors develop planned regular routines for medication-taking, and addressing any concerns or misconceptions about their medication, can improve adherence and thus potentially patient outcomes. (PsycINFO Database Record (c) 2014 APA, all rights reserved).
    Health Psychology 07/2014; 33(10). DOI:10.1037/hea0000082 · 3.95 Impact Factor
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    ABSTRACT: Objective Fatigue is often distressing for stroke survivors. The time course of clinically significant fatigue in the first year after stroke is uncertain. We aimed to determine the frequency, severity and time course of clinically significant fatigue in the first 12 months after stroke onset. Methods We recruited patients with a recent acute stroke. At about one month, six months and 12 months, we performed a structured interview to identify clinically significant fatigue (case definition), and assessed fatigue severity (Fatigue Assessment Scale (FAS)). Results Of 157 patients who initially consented, 136 attended at least one assessment. At one month, 43/132 (33%) had clinically significant fatigue. Eighty-six attended all three assessments, of whom clinically significant fatigue was present in 24 (28%) at one month, 20 (23%) at six months and 18 (21%) at 12 months; their median (IQR) FAS scores were 23 (18 to 29), 21 (17 to 25) and 22.5 (17 to 28) at one, six and 12 months respectively. Of 101 patients who attended at least the one and six month assessments, fatigue status did not change in 65 (64%), with 9 (9%) fatigued throughout and 56 (55%) non-fatigued throughout; 15 (15%) became non-fatigued, 9 (9%) became fatigued, and in 12 (12%) fatigue status fluctuated across three assessments. Conclusion Clinically significant fatigue affected a third of patients one month after stroke. About two thirds of these patients had become non-fatigued by six months, most of whom remained non-fatigued at 12 months. Fatigue persists in a third at 12 months.
    Journal of Psychosomatic Research 07/2014; 77(5). DOI:10.1016/j.jpsychores.2014.06.013 · 2.84 Impact Factor
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    ABSTRACT: Background and aim Randomised trials indicate that stroke unit care reduces morbidity and mortality after stroke. Similar results have been seen in observational studies but many have not corrected for selection bias or independent predictors of outcome. We evaluated the effect of stroke unit compared with general ward care on outcomes after stroke in Scotland, adjusting for case mix by incorporating the six simple variables (SSV) model, also taking into account selection bias and stroke subtype. Methods We used routine data from National Scottish datasets for acute stroke patients admitted between 2005 and 2011. Patients who died within 3 days of admission were excluded from analysis. The main outcome measures were survival and discharge home. Multivariable logistic regression was used to estimate the OR for survival, and adjustment was made for the effect of the SSV model and for early mortality. Cox proportional hazards model was used to estimate the hazard of death within 365 days. Results There were 41 692 index stroke events; 79% were admitted to a stroke unit at some point during their hospital stay and 21% were cared for in a general ward. Using the SSV model, we obtained a receiver operated curve of 0.82 (SE 0.002) for mortality at 6 months. The adjusted OR for survival at 7 days was 3.11 (95% CI 2.71 to 3.56) and at 1 year 1.43 (95% CI 1.34 to 1.54) while the adjusted OR for being discharged home was 1.19 (95% CI 1.11 to 1.28) for stroke unit care. Conclusions In routine practice, stroke unit admission is associated with a greater likelihood of discharge home and with lower mortality up to 1 year, after correcting for known independent predictors of outcome, and excluding early non-modifiable mortality.
    Journal of neurology, neurosurgery, and psychiatry 06/2014; DOI:10.1136/jnnp-2013-307478 · 5.58 Impact Factor
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    ABSTRACT: The objective of this study was to: (1) systematically review the reporting and methods used in the development of clinical prediction models for recurrent stroke or myocardial infarction (MI) after ischemic stroke; (2) to meta-analyze their external performance; and (3) to compare clinical prediction models to informal clinicians' prediction in the Edinburgh Stroke Study (ESS). We searched Medline, EMBASE, reference lists and forward citations of relevant articles from 1980 to 19 April 2013. We included articles which developed multivariable clinical prediction models for the prediction of recurrent stroke and/or MI following ischemic stroke. We extracted information to assess aspects of model development as well as metrics of performance to determine predictive ability. Model quality was assessed against a pre-defined set of criteria. We used random-effects meta-analysis to pool performance metrics. We identified twelve model development studies and eleven evaluation studies. Investigators often did not report effective sample size, regression coefficients, handling of missing data; typically categorized continuous predictors; and used data dependent methods to build models. A meta-analysis of the area under the receiver operating characteristic curve (AUROCC) was possible for the Essen Stroke Risk Score (ESRS) and for the Stroke Prognosis Instrument II (SPI-II); the pooled AUROCCs were 0.60 (95% CI 0.59 to 0.62) and 0.62 (95% CI 0.60 to 0.64), respectively. An evaluation among minor stroke patients in the ESS demonstrated that clinicians discriminated poorly between those with and those without recurrent events and that this was similar to clinical prediction models. The available models for recurrent stroke discriminate poorly between patients with and without a recurrent stroke or MI which was similar to the discrimination achieved by informal clinicians' predictions. Formal prediction may be improved by addressing commonly encountered methodological flaws.
    BMC Medicine 04/2014; 12(1):58. DOI:10.1186/1741-7015-12-58 · 7.28 Impact Factor
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    ABSTRACT: Patients with transient ischaemic attack (TIA) or minor stroke need rapid treatment of risk factors to prevent recurrent stroke. ABCD2 score or magnetic resonance diffusion-weighted brain imaging (MR DWI) may help assessment and treatment. Is MR with DWI cost-effective in stroke prevention compared with computed tomography (CT) brain scanning in all patients, in specific subgroups or as 'one-stop' brain-carotid imaging? What is the current UK availability of services for stroke prevention? Published literature; stroke registries, audit and randomised clinical trials; national databases; survey of UK clinical and imaging services for stroke; expert opinion. Systematic reviews and meta-analyses of published/unpublished data. Decision-analytic model of stroke prevention including on a 20-year time horizon including nine representative imaging scenarios. The pooled recurrent stroke rate after TIA (53 studies, 30,558 patients) is 5.2% [95% confidence interval (CI) 3.9% to 5.9%] by 7 days, and 6.7% (5.2% to 8.7%) at 90 days. ABCD2 score does not identify patients with key stroke causes or identify mimics: 66% of specialist-diagnosed true TIAs and 35-41% of mimics had an ABCD2 score of ≥ 4; 20% of true TIAs with ABCD2 score of < 4 had key risk factors. MR DWI (45 studies, 9078 patients) showed an acute ischaemic lesion in 34.3% (95% CI 30.5% to 38.4%) of TIA, 69% of minor stroke patients, i.e. two-thirds of TIA patients are DWI negative. TIA mimics (16 studies, 14,542 patients) make up 40-45% of patients attending clinics. UK survey (45% response) showed most secondary prevention started prior to clinic, 85% of primary brain imaging was same-day CT; 51-54% of patients had MR, mostly additional to CT, on average 1 week later; 55% omitted blood-sensitive MR sequences. Compared with 'CT scan all patients' MR was more expensive and no more cost-effective, except for patients presenting at > 1 week after symptoms to diagnose haemorrhage; strategies that triaged patients with low ABCD2 scores for slow investigation or treated DWI-negative patients as non-TIA/minor stroke prevented fewer strokes and increased costs. 'One-stop' CT/MR angiographic-plus-brain imaging was not cost-effective. Data on sensitivity/specificity of MR in TIA/minor stroke, stroke costs, prognosis of TIA mimics and accuracy of ABCD2 score by non-specialists are sparse or absent; all analysis had substantial heterogeneity. Magnetic resonance with DWI is not cost-effective for secondary stroke prevention. MR was most helpful in patients presenting at > 1 week after symptoms if blood-sensitive sequences were used. ABCD2 score is unlikely to facilitate patient triage by non-stroke specialists. Rapid specialist assessment, CT brain scanning and identification of serious underlying stroke causes is the most cost-effective stroke prevention strategy. The National Institute for Health Research Health Technology Assessment programme.
    04/2014; 18(27):1-368. DOI:10.3310/hta18270
  • Martin Dennis
    The Lancet Neurology 04/2014; 13(4):344-6. DOI:10.1016/S1474-4422(14)70043-2 · 21.82 Impact Factor
  • Anne Rowat, Catriona Graham, Martin Dennis
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    ABSTRACT: Renal dysfunction (i.e. a reduced estimated glomerular filtration rate, eGFR) is commonly found in hospitalized stroke patients but its associations with patients' characteristics and outcome require further investigation. We linked clinical data from stroke patients enrolled between 2005 and 2008 into two prospective hospital registers with routine laboratory eGFR data. The eGFR was calculated using the Modification of Diet in Renal Disease method and renal dysfunction was defined as <60 ml/min/1·73 m(2) . In addition we systematically reviewed studies investigating the association between eGFR and outcome after stroke. Of 2520 patients who had an eGFR measured on admission hospital, 805 (32%) had renal dysfunction. On multivariate analysis, renal dysfunction was significantly less likely in those with a predicted good outcome (OR 0·27, 95% CI 0·21, 0·36) based on the well-validated six simple variable model. After adjustment for other predictive factors, stroke patients with renal dysfunction were more likely to die in hospital compared with those without (odds ratio 1·59, 95% confidence intervals 1·26, 2·00). Of the 31 studies involving 41 896 participants included in the systematic review, 18 studies found that low eGFR was an independent predictor of death and 6 reported a significant association with death and disability. Our findings suggest that renal dysfunction on admission is common and associated with poor outcomes over the first year. Further work is required to establish to what extent these associations are causal and whether treating impaired renal function improves outcomes.
    International Journal of Stroke 03/2014; 9(5). DOI:10.1111/ijs.12264 · 4.03 Impact Factor
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    ABSTRACT: To determine the magnitude of potentially causal relationships among vascular risk factors (VRFs), large-artery atheromatous disease (LAD), and cerebral white matter hyperintensities (WMH) in 2 prospective cohorts. We assessed VRFs (history and measured variables), LAD (in carotid, coronary, and leg arteries), and WMH (on structural MRI, visual scores and volume) in: (a) community-dwelling older subjects of the Lothian Birth Cohort 1936, and (b) patients with recent nondisabling stroke. We analyzed correlations, developed structural equation models, and performed mediation analysis to test interrelationships among VRFs, LAD, and WMH. In subjects of the Lothian Birth Cohort 1936 (n = 881, mean age 72.5 years [SD ±0.7 years], 49% with hypertension, 33% with moderate/severe WMH), VRFs explained 70% of the LAD variance but only 1.4% to 2% of WMH variance, of which hypertension explained the most. In stroke patients (n = 257, mean age 74 years [SD ±11.6 years], 61% hypertensive, 43% moderate/severe WMH), VRFs explained only 0.1% of WMH variance. There was no direct association between LAD and WMH in either sample. The results were the same for all WMH measures used. The small effect of VRFs and LAD on WMH suggests that WMH have a large "nonvascular," nonatheromatous etiology. VRF modification, although important, may be limited in preventing WMH and their stroke and dementia consequences. Investigation of, and interventions against, other suspected small-vessel disease mechanisms should be addressed.
    Neurology 03/2014; 82(15). DOI:10.1212/WNL.0000000000000312 · 8.30 Impact Factor
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    ABSTRACT: : Care of stroke patients costs considerably more in specialized stroke units (SU) compared to care in general medical wards (GMW) but the technology may be cost effective if it leads to significantly improved outcomes. While randomized control trials show better outcomes for stroke patients admitted to SU, observational studies report mixed findings. In this paper we use individual level data from first-ever stroke patients in four European cities and find evidence of selection by the initial severity of stroke into SU in some cities. In these cases, the impact of admission to SU on outcomes is overestimated by multivariate logit models even after controlling for case-mix. However, when the imbalance in patient characteristics and severity of stroke by admission to SU and GMW is adjusted using propensity score methods, the differences in outcomes are no longer statistically significant in most cases. Our analysis explains why earlier studies using observational data have found mixed results on the benefits of admission to SU.
    01/2014; 4(1):1. DOI:10.1186/2191-1991-4-1

Publication Stats

8k Citations
2,128.25 Total Impact Points

Institutions

  • 1995–2015
    • The University of Edinburgh
      • • Division of Clinical Neurosciences
      • • Department of Geriatric Medicine
      Edinburgh, Scotland, United Kingdom
  • 1993–2014
    • Western General Hospital
      Edinburgh, Scotland, United Kingdom
    • Royal Perth Hospital
      Perth City, Western Australia, Australia
  • 2012
    • King's College London
      • Division of Health and Social Care Research
      Londinium, England, United Kingdom
  • 2008
    • The Bracton Centre, Oxleas NHS Trust
      Дартфорде, England, United Kingdom
  • 2007
    • Edinburgh Napier University
      • School of Nursing, Midwifery & Social Care
      Edinburgh, Scotland, United Kingdom
  • 2001
    • University of Aberdeen
      Aberdeen, Scotland, United Kingdom
  • 1990
    • University of Oxford
      • Nuffield Department of Clinical Neurosciences
      Oxford, England, United Kingdom