Martin Dennis

The University of Edinburgh, Edinburgh, Scotland, United Kingdom

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Publications (288)2245.98 Total impact

  • Rustam Al-Shahi Salman, Martin S Dennis
    Stroke 09/2014; · 6.16 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; · 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 : official journal of the Division of Health Psychology, American Psychological Association. 07/2014;
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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; · 3.27 Impact Factor
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    ABSTRACT: Venous thromboembolism (VTE) is associated with considerable morbidity and mortality in stroke patients. The purpose of our survey was to establish the current methods of VTE prophylaxis practiced by Polish neurologists. We also aimed to determine whether there is enough variation in practice to justify the development of an evidence-based guideline for VTE prevention.
    Archives of Medical Science 06/2014; 10(3):470-6. · 1.89 Impact Factor
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    ABSTRACT: 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.
    Journal of neurology, neurosurgery, and psychiatry 06/2014; · 4.87 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. · 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.
    Health technology assessment (Winchester, England). 04/2014; 18(27):1-368.
  • Martin Dennis
    The Lancet Neurology 04/2014; 13(4):344-6. · 23.92 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; · 2.75 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; · 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.
    Health economics review. 01/2014; 4(1):1.
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    ABSTRACT: 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).
    PLoS ONE 01/2014; 9(10):e110189. · 3.53 Impact Factor
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    ABSTRACT: Generic (i.e. non-branded medicine) and therapeutic (i.e. a less expensive drug from the same class) substitution of medication provides considerable financial savings, but may negatively impact on patients. We report secondary qualitative/quantitative analysis of stroke survivors from a pilot randomised controlled brief intervention to increase adherence to medication. Patients' experiences of medication changes were examined in conjunction with electronically-recorded medication adherence. Twenty-eight patients reported frequent medication changes (e.g. size/shape/colour/packaging) and two-thirds of these reported negative effects, resulting in, at least, confusion and, at worst, mistakes in medication-taking. Patients reporting a direct effect on their medication-taking (n = 6) demonstrated poorer objectively-measured adherence (i.e. % doses taken on schedule) than those reporting confusion [mean difference = 19.9, 95 % CI (2.0, 37.8)] or no problems [mean difference = 20.6, 95 % CI (1.6, 40.0)]. Changes to medication resulting from switching between generic brands can be associated with notable problems, including poorer medication adherence, for a significant minority.
    Journal of Behavioral Medicine 12/2013; · 3.10 Impact Factor
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  • The Lancet 11/2013; 382(9903):1481-2. · 39.21 Impact Factor
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    ABSTRACT: Patients with any type of stroke managed in organized inpatient (stroke unit) care are more likely to survive, return home, and regain independence. However, it is uncertain whether these benefits apply equally to patients with intracerebral hemorrhage and ischemic stroke. We conducted a secondary analysis of a systematic review of controlled clinical trials comparing stroke unit care with general ward care, including only trials published after 1990 that could separately report outcomes for patients with intracerebral hemorrhage and ischemic stroke. We performed random-effects meta-analyses and tested for subgroup interactions by stroke type. We identified 13 trials (3570 patients) of modern stroke unit care that recruited patients with intracerebral hemorrhage and ischemic stroke, of which 8 trials provided data on 2657 patients. Stroke unit care reduced death or dependency (risk ratio [RR], 0.81; 95% confidence interval [CI], 0.471-0.92; P=0.0009; I(2) =60%) with no difference in benefits for patients with intracerebral hemorrhage (RR, 0.79; 95% CI, 0.61-1.00) than patients with ischemic stroke (RR, 0.82; 95% CI, 0.70-0.97; Pinteraction=0.77). Stroke unit care reduced death (RR, 0.79; 95% CI, 0.64-0.97; P=0.02; I(2) =49%) to a greater extent for patients with intracerebral hemorrhage (RR, 0.73; 95% CI, 0.54-0.97) than patients with ischemic stroke (RR, 0.82; 95%, CI 0.61-1.09), but this difference was not statistically significant (Pinteraction=0.58). Patients with intracerebral hemorrhage seem to benefit at least as much as patients with ischemic stroke from organized inpatient (stroke unit) care.
    Stroke 09/2013; · 6.16 Impact Factor
  • Stroke 09/2013; · 6.16 Impact Factor
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Publication Stats

9k Citations
2,245.98 Total Impact Points

Institutions

  • 1994–2014
    • The University of Edinburgh
      • Division of Clinical Neurosciences
      Edinburgh, Scotland, United Kingdom
  • 1990–2014
    • Western General Hospital
      Edinburgh, Scotland, United Kingdom
  • 2012–2013
    • King's College London
      • • Division of Health and Social Care Research
      • • Department of Primary Care and Public Health Sciences
      London, ENG, United Kingdom
    • University of Glasgow
      Glasgow, Scotland, United Kingdom
  • 2010–2013
    • University of Stirling
      • Department of Psychology
      Stirling, SCT, United Kingdom
  • 2007–2011
    • Edinburgh Napier University
      • School of Nursing, Midwifery & Social Care
      Edinburgh, SCT, United Kingdom
    • University of Leeds
      • Division of Clinical Trials Research
      Leeds, ENG, United Kingdom
  • 2008–2010
    • The Bracton Centre, Oxleas NHS Trust
      Дартфорде, England, United Kingdom
    • Oslo University Hospital
      Kristiania (historical), Oslo County, Norway
  • 2006
    • Monash University (Australia)
      • Department of Nephrology
      Melbourne, Victoria, Australia
    • Medical University of Gdansk
      • Department of Adult Neurology
      Gdańsk, Pomeranian Voivodeship, Poland
  • 2001
    • University of Aberdeen
      Aberdeen, Scotland, United Kingdom
  • 1999
    • The Newcastle upon Tyne Hospitals NHS Foundation Trust
      • Department of Neurology
      Newcastle-on-Tyne, England, United Kingdom
  • 1998
    • University of Southampton
      Southampton, England, United Kingdom
  • 1993
    • Royal Perth Hospital
      Perth City, Western Australia, Australia