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M S Dennis

Publications and source records attributed to M S Dennis.

At least 19 recordsLinked to original sources
PubMed2006

Sleep-disordered breathing after stroke: a randomised controlled trial of continuous positive airway pressure.

BACKGROUND: Sleep-disordered breathing (SDB) is common after stroke, but it is unclear whether it should be treated. OBJECTIVE: To conduct a randomised controlled trial of continuous positive airway pressure (CPAP) after stroke. METHODS: Patients with stroke with > or = 30 apnoeas and hypopnoeas per hour ((A+H)/h) with predominant obstructive sleep apnoea or hypopnoea were randomised to either CPAP treatment or conservative treatment for 8 weeks. Outcomes were measured blind to treatment allocation at 8 weeks and 6 months after the stroke. The primary outcome was physical function on the Nottingham Extended Activities of Daily Living Scale. RESULTS: Of 658 patients with stroke screened, only 71 (10.7%) were eligible and consented to a sleep study 14-19 days after stroke. 66 patients completed the sleep study (21 women; mean age 72 years), 33 (50%) had > or = 30 (A+H)/h that were predominantly obstructive. 15 were randomised to CPAP treatment and 15 to conventional treatment. Despite intensive efforts, objective use of CPAP was poor, averaging 1.4 h a night. CPAP treatment resulted in no significant improvements (p>0.1) in the primary outcome or in neurological function or sleepiness, and in poorer health status on some measures. CONCLUSIONS: This trial showed no benefit from CPAP treatment, the relevance of the observed detrimental effects is questionable. Even in our highly selected patients with stroke, use of CPAP was poor. At present, CPAP treatment should be advocated for patients with stroke only if they have symptoms of SDB.

Activities of Daily Living↗
PubMed2006

MR diffusion-weighted imaging and outcome prediction after ischemic stroke.

BACKGROUND: MR diffusion-weighted imaging (DWI) shows acute ischemic lesions early after stroke so it might improve outcome prediction and reduce sample sizes in stroke treatment trials. Previous studies of DWI and outcome produced conflicting results. OBJECTIVE: To determine whether DWI lesion characteristics independently predict outcome in a broad range of patients with acute stroke. METHODS: The authors recruited hospital-admitted patients with all severities of suspected stroke, assessed stroke severity on the NIH Stroke Scale (NIHSS), performed early brain DWI, and assessed outcome at 3 months (modified Rankin Scale). Clinical data and DWI lesion parameters were evaluated in a logistic regression model to identify independent predictors of outcome at 3 months and a previously described "Three-Item Scale" (including DWI) was tested for outcome prediction. RESULTS: Among 82 patients (mean NIHSS 7.1 [+/-6.3 SD]), the only independent outcome predictors were age and stroke severity. Neither DWI lesion volume nor apparent diffusion coefficient nor the previously described Three-Item Scale predicted outcome independently. Comparison with previous studies suggested that DWI may predict outcome only in patients with more severe cortical ischemic strokes. CONCLUSIONS: Across a broad range of stroke severities, diffusion-weighted imaging (DWI) did not predict outcome beyond that of key clinical variables. Thus, DWI is unlikely to reduce sample sizes in acute stroke trials assessing functional outcome, especially where estimated treatment effects are modest.

Acute Disease↗
PubMed2006

No evidence that severity of stroke in internal carotid occlusion is related to collateral arteries.

BACKGROUND/AIM: The neurological effects of internal carotid artery (ICA) occlusion vary between patients. The authors investigated whether the severity of symptoms in a large group of patients with ipsilateral or/and contralateral ICA occlusion at presentation with ocular or cerebral ischaemic symptoms could be explained by patency of other extra or intracranial arteries to act as collateral pathways. METHODS: The authors prospectively identified all patients (n = 2881) with stroke, cerebral transient ischaemic attack (TIA), retinal artery occlusion (RAO), and amaurosis fugax (AFx) presenting to our hospital over five years, obtained detailed history and examination, and examined the intra and extracranial arteries with carotid and colour-power transcranial Doppler ultrasound. For this analysis, all those with intracranial haemorrhage on brain imaging and cerebral events without brain imaging were excluded. RESULTS: Among 2228/2397 patients with brain imaging (1713 ischaemic strokes, 401 cerebral TIAs, 193 AFx, and 90 RAO) who underwent carotid Doppler, 195 (9%) had ICA occlusion. Among those patients with cortical events, disease in potential collateral arteries (contralateral ICA, external carotid, ipsilateral or contralateral vertebral or intracranial arteries) was equally distributed among patients with severe and mild ischaemic presenting symptoms. CONCLUSION: The authors found no evidence that the clinical presentation associated with an ICA occlusion was related to patency of other extra or intracranial arteries to act as collateral pathways. Further work is required to investigate what determines the clinical effects of ICA occlusion.

Amaurosis Fugax↗
PubMed2005

Do acute diffusion- and perfusion-weighted MRI lesions identify final infarct volume in ischemic stroke?

BACKGROUND AND PURPOSE: An acute mismatch on diffusion-weighted MRI (DWI) and perfusion-weighted MRI (PWI) may represent the "tissue-at-risk." It is unclear which "semiquantitative" perfusion parameter most closely identifies final infarct volume. METHODS: Acute stroke patients underwent DWI and PWI (dynamic-susceptibility contrast imaging) on admission (baseline), and T2-weighted imaging (T2WI) at 1 or 3 months after stroke. "Semiquantitative" mean transit time (MTTsq=first moment of concentration/time curve), cerebral blood volume (CBVsq=area under concentration/time curve), and cerebral blood flow (CBFsq=CBVsq/MTTsq) were calculated. DWI and PWI lesions were measured at baseline and final infarct volume on T2WI acquired > or =1 month after stroke. Baseline DWI, CBFsq, and MTTsq lesion volumes were compared with final T2WI lesion volume. RESULTS: Among 46 patients, baseline DWI and CBFsq lesions were not significantly different from final T2WI lesion volume, but baseline MTTsq lesions were significantly larger. The correlation with final T2WI lesion volume was strongest for DWI (Spearman rank correlation coefficient rho=0.68), intermediate for CBFsq (rho=0.55), and weakest for MTTsq (rho=0.49) baseline lesion volumes. Neither DWI/CBFsq nor DWI/MTTsq mismatch predicted lesion growth; lesion growth was equally common in those with and without mismatch. CONCLUSIONS: Of the 2 PWI parameters, CBFsq lesions most closely identifies, and MTTsq overestimates, final T2WI lesion volume. "DWI/PWI mismatch" does not identify lesion growth. Patients without "DWI/PWI mismatch" are equally likely to have lesion growth as those with mismatch and should not be excluded from acute stroke treatment.

Adult↗
PubMed2005

Magnetic resonance brain imaging in patients with acute stroke: feasibility and patient related difficulties.

OBJECTIVES: To assess organisational and patient specific limitations and safety of magnetic resonance imaging (MRI) as the first line investigation for hospital admitted stroke patients. METHODS: Consecutive patients admitted with acute stroke were assessed and an attempt was made to perform MRI in all patients. Oxygen saturation and interventions required during scanning were recorded. RESULTS: Among 136 patients recruited over 34 weeks, 85 (62%) underwent MRI. The patients' medical instability (15 of the 53 not scanned), contraindications to MRI (six of the 53 not scanned), and rapid symptom resolution (10 of the 53 not scanned) were the main reasons for not performing MRI. Of the 85 patients who underwent MRI, 26 required physical intervention, 17 did not complete scanning, and 11 of the 61 who had successful oxygen saturation monitoring were hypoxic during MRI. Organisational limitations accounted for only 13% of failures to scan. CONCLUSIONS: Up to 85% of hospital admitted acute stroke patients could have MRI as first line imaging investigation, but medical instability is the major limitation. Hypoxia is frequent in MRI. Patients should be monitored carefully, possibly by an experienced clinician, during scanning.

Acute Disease↗
PubMed2004

A study of statin use in the prevention of cognitive impairment of vascular origin in the UK.

INTRODUCTION: There is increasing evidence suggesting that control of hypertension and antiplatelet therapy may prevent or reduce progression of vascular-related cognitive impairment (VCI), though a similar role of statins in this group of patients has yet to be established. METHODS: We conducted a postal survey of a group of 296 medical practitioners (comprising of physicians and psychiatrists specialising in the elderly, and general practitioners) inquiring into their management of (a) patients at high risk of developing VCI and (b) patients with established VCI. RESULTS: The overall response rate was 60% (177/296), with the highest response rate from psychiatrists. (a) For patients at high risk of developing VCI: 47% of clinicians believed that statins had an important role in preventing subsequent dementia: 4% would commence statins at a total cholesterol (TC) of 4-5 mmol/L; 38% with a TC of 5.1-6.5 mmol/L; and 32% with a TC of 6.6-8 mmol/L. Cardiovascular risk profile, age, cost and gender were other factors considered as important factors influencing statin prescription. (b) In those patients with established VCI: 32% of clinicians felt that statins had an important role in arresting progression, usually in people with a mild degree of cognitive impairment: 4% would commence statins at a TC of 4-5 mmol/L; 25% with a TC of 5.1-6.5 mmol/L; and 22% with a TC of 6.6-8 mmol/L. There were no major differences between clinicians in their prescribing habits. CONCLUSIONS: A substantial proportion of clinicians favour the use of statins in primary and secondary prevention of cognitive impairment of vascular origin, despite a lack of definite evidence to support their use at the present time.

Aged↗
PubMed2004

Change in stroke incidence, mortality, case-fatality, severity, and risk factors in Oxfordshire, UK from 1981 to 2004 (Oxford Vascular Study).

BACKGROUND: The incidence of stroke is predicted to rise because of the rapidly ageing population. However, over the past two decades, findings of randomised trials have identified several interventions that are effective in prevention of stroke. Reliable data on time-trends in stroke incidence, major risk factors, and use of preventive treatments in an ageing population are required to ascertain whether implementation of preventive strategies can offset the predicted rise in stroke incidence. We aimed to obtain these data. METHODS: We ascertained changes in incidence of transient ischaemic attack and stroke, risk factors, and premorbid use of preventive treatments from 1981-84 (Oxford Community Stroke Project; OCSP) to 2002-04 (Oxford Vascular Study; OXVASC). FINDINGS: Of 476 patients with transient ischaemic attacks or strokes in OXVASC, 262 strokes and 93 transient ischaemic attacks were incident events. Despite more complete case-ascertainment than in OCSP, age-adjusted and sex-adjusted incidence of first-ever stroke fell by 29% (relative incidence 0.71, 95% CI 0.61-0.83, p=0.0002). Incidence declined by more than 50% for primary intracerebral haemorrhage (0.47, 0.27-0.83, p=0.01) but was unchanged for subarachnoid haemorrhage (0.83, 0.44-1.57, p=0.57). Thus, although 28% more incident strokes (366 vs 286) were expected in OXVASC due to demographic change alone (33% increase in those aged 75 or older), the observed number fell (262 vs 286). Major reductions were recorded in mortality rates for incident stroke (0.63, 0.44-0.90, p=0.02) and in incidence of disabling or fatal stroke (0.60, 0.50-0.73, p<0.0001), but no change was seen in case-fatality due to incident stroke (17.2% vs 17.8%; age and sex adjusted relative risk 0.85, 95% CI 0.57-1.28, p=0.45). Comparison of premorbid risk factors revealed substantial reductions in the proportion of smokers, mean total cholesterol, and mean systolic and diastolic blood pressures and major increases in premorbid treatment with antiplatelet, lipid-lowering, and blood pressure lowering drugs (all p<0.0001). INTERPRETATION: The age-specific incidence of major stroke in Oxfordshire has fallen by 40% over the past 20 years in association with increased use of preventive treatments and major reductions in premorbid risk factors.

Adult↗
PubMed2004

Personality change after stroke: some preliminary observations.

OBJECTIVES: To describe changes in personality after stroke and effects on carers. METHODS: A consecutive series of patients was recruited from hospital admissions with stroke. A novel questionnaire was administered to the patients' main carer at nine months after the stroke to determine their perception of the patients' pre-stroke and post-stroke personality. Personality change was identified by changes in these ratings, and associations between personality change and the following variables explored: emotional disorder in patients and carers (measured using the hospital anxiety and depression scale and a structured psychiatric interview), stroke classification (Oxford community stroke classification), residual disability (Barthel index and Nottingham extended activities of daily living scale), and lesion characteristics on computed tomography (CT). RESULTS: Carers of 35 patients with stroke took part. Reported changes in personality after stroke included: reduced patience and increased frustration (both p<0.0001, t test of difference), reduced confidence, more dissatisfaction, and a less easy going nature (all p<0.005). Occasionally, aspects of personality change were seen as positive by carers. There were relations between greater personality change and interviewer rated patient depression or anxiety (p<0.001) but not when this was self rated; and between personality change and both emotional disorder in carers (p<0.005) and greater disability (p<0.01) but not CT lesion characteristics. CONCLUSIONS: Carers commonly perceive personality change in stroke patients. This is associated with self rated emotional distress in the carer. More research is needed to understand what carers mean by "personality change" and what factors contribute to the perceived change.

Activities of Daily Living↗
PubMed2004

Are multiple acute small subcortical infarctions caused by embolic mechanisms?

OBJECTIVE: To seek evidence of potential embolic sources or other stroke mechanisms in patients who, on chance observation, had several apparently recent small subcortical infarcts on diffusion weighted magnetic resonance imaging (DWI). METHODS: Patients presenting with stroke and multiple hyperintense subcortical infarcts visible on DWI were identified prospectively. Detailed clinical and radiological assessments were done independently and blinded to each other. RESULTS: Of 10 patients with multiple hyperintense subcortical infarcts on DWI, a definite embolic source was identified in only one. Most patients were hypertensive and smoked. The DWI appearance suggested that the subcortical lesions had occurred within several weeks rather than at exactly the same time. Most patients also had significant white matter hyperintensities and four had microhaemorrhages. CONCLUSIONS: Embolic sources were not identified in most patients but they did have systemic vascular risk factors and brain imaging features of "small vessel disease." A more generalised intrinsic process affecting many small cerebral vessels contemporaneously could explain multiple acute small subcortical infarcts. White matter hyperintensities, microhaemorrhages, and multiple small subcortical infarcts may share a common pathophysiological mechanism such as a diffuse cerebral microvascular abnormality which requires further exploration.

Acute Disease↗
PubMed2004

What is the best imaging strategy for acute stroke?

OBJECTIVES: To determine the cost-effectiveness of computed tomographic (CT) scanning after acute stroke. To assess the contribution of brain imaging to the diagnosis and management of stroke, and to estimate the costs, benefits and risks of different imaging strategies in order to provide data to inform national and local policy on the use of brain imaging in stroke. DESIGN: A decision-analysis model was developed to represent the pathway of care in acute stroke using 'scan all patients within 48 hours' as the comparator against which to cost 12 alternative scan strategies. SETTING: Hospitals in Scotland. PARTICIPANTS: Subjects were patients admitted to hospital with a first stroke and those managed as outpatients. INTERVENTIONS: The effect on functional outcome after ischaemic or haemorrhagic stroke, tumours or infections, of correctly administered antithrombotic or other treatment; of time to scan and stroke severity on diagnosis by CT or MRI; on management, including length of stay, functional outcome, and quality-adjusted life years (QALYs), of the diagnostic information provided by CT scanning; the cost-effectiveness (cost versus QALYs) of different strategies for use of CT after acute stroke. MAIN OUTCOME MEASURES: Death and functional outcome at long-term follow-up; accuracy of CT and MRI; cost of CT scanning by time of day and week; effect of CT diagnosis on change in health outcome, length of stay in hospital and QALYs; cost-effectiveness of various scanning strategies. RESULTS: CT is very sensitive and specific for haemorrhage within the first 8 days of stroke only. Suboptimal scanning used in epidemiology studies suggests that the frequency of primary intracerebral haemorrhage (PICH) has been underestimated. Aspirin increases the risk of PICH. There were no reliable data on functional outcome or on the effect of antithrombotic treatment given long term after PICH. In 60% of patients with recurrent stroke after PICH, the cause is another PICH and mortality is high among PICH patients. A specific MR sequence (gradient echo) is required to identify prior PICH reliably. CT scanners were distributed unevenly in Scotland, 65% provided CT scanning within 48 hours of stroke, and 100% within 7 days for hospital-admitted patients, but access out of hours was very variable, and for outpatients was poor. The average cost of a CT brain scan for stroke was pounds 30.23 to pounds 89.56 in normal working hours and pounds 55.05 to pounds 173.46 out of hours. Average length of stay was greatest for severe strokes and those who survived in a dependent state. For a cohort of 1000 patients aged 70-74 years, the policy 'scan all strokes within 48 hours', cost pounds 10,279,728 and achieved 1982.3 QALYS. The most cost-effective strategy was 'scan all immediately' (pounds 9,993,676 and 1982.4 QALYS). The least cost-effective was to 'scan patients on anticoagulants, in a life-threatening condition immediately and the rest within 14 days'. CONCLUSIONS: In general, strategies in which most patients were scanned immediately cost least and achieved the most QALYs, as the cost of providing CT (even out of hours) was less than the cost of inpatient care. Increasing independent survival by even a small proportion through early use of aspirin in the majority with ischaemic stroke, avoiding aspirin in those with haemorrhagic stroke, and appropriate early management of those who have not had a stroke, reduced costs and increased QALYs.

Aged↗
PubMed2004

In which patients is diffusion-weighted magnetic resonance imaging most useful in routine stroke care?

BACKGROUND AND PURPOSE: Magnetic resonance (MR) diffusion-weighted imaging (DWI) has been used extensively in hyperacute cortical ischemic stroke, but its broader role in the assessment of patients presenting at later times after a wider variety of strokes has been less widely studied. METHODS: The authors assessed the clinical usefulness of DWI across a range of patients referred prospectively as either inpatients or outpatients. Detailed clinical information was collected. Diffusion (DWI) and T2-weighted images were read separately and blindly to clinical details. The presence of any infarct and its type were noted. RESULTS: In 153 stroke patients, imaged at a median of 2 days (range, 6 hours to 77 days) after stroke, recent infarcts were identified more often on DWI (70%) than on T2-weighted MRI (32%) in all severities of stroke. The proportion of scans on which relevant lesions were only seen on DWI was greatest among milder strokes due to small cortical or lacunar infarcts and among patients imaged later rather than earlier after the stroke. CONCLUSIONS: DWI is clinically useful up to several weeks after stroke, not just within the first few hours, and especially in patients with minor strokes.

Adult↗
PubMed2003

Very early risk of stroke after a first transient ischemic attack.

BACKGROUND AND PURPOSE: The commonly quoted early risks of stroke after a first transient ischemic attack (TIA)-1% to 2% at 7 days and 2% to 4% at 1 month-are likely to be underestimates because of the delay before inclusion into previous studies and the exclusion of patients who had a stroke during this time. Therefore, it is uncertain how urgently TIA patients should be assessed. We used data from the Oxford Community Stroke Project (OCSP) to estimate the very early stroke risk after a TIA and investigated the potential effects of the delays before specialist assessment. METHODS: All OCSP patients who had a first-ever definite TIA during the study period (n=209) were included. Three analyses were used to estimate the early stroke risk after a first TIA starting from 3 different dates: assessment by a neurologist, referral to the TIA service, and onset of first TIA. RESULTS: The stroke risk from assessment by a neurologist was 1.9% [95% confidence interval (CI), 0.1 to 3.8] at 7 days and 4.4% (95% CI, 1.6 to 7.2) at 30 days. The 7- and 30-day stroke risks from referral were 2.4% (95% CI, 0.3 to 4.5) and 4.9% (95% CI, 1.9 to 7.8), respectively, and from onset of first-ever TIA were 8.6% (95% CI, 4.8 to 12.4) and 12.0% (95% CI, 7.6 to 16.4), respectively. CONCLUSIONS: The early risk of stroke from date of first-ever TIA is likely to be higher than commonly quoted. Public education about the symptoms of TIA is needed so that medical attention is sought more urgently and stroke prevention strategies are implemented sooner.

Aged↗
PubMed2003

Is breakdown of the blood-brain barrier responsible for lacunar stroke, leukoaraiosis, and dementia?

BACKGROUND: The pathogenesis of and relationship between small deep (lacunar) infarcts, cerebral white matter disease (leukoaraiosis or white matter hyperintensities), and progressive cognitive impairment or dementia are much debated. SUMMARY OF COMMENT: We hypothesize that cerebral small-vessel endothelial (ie, blood-brain barrier) dysfunction, with leakage of plasma components into the vessel wall and surrounding brain tissue leading to neuronal damage, may contribute to the development of 3 overlapping and disabling cerebrovascular conditions: lacunar stroke, leukoaraiosis, and dementia. This hypothesis could explain the link between ischemic cerebral small-vessel disease and several apparently clinically distinct dementia syndromes. This hypothesis is supported by pathological, epidemiological, and experimental studies in lacunar stroke and leukoaraiosis and observations on the blood-brain barrier with MRI. We suspect that the potential significance of blood-brain barrier failure as a pathogenetic step linking vascular disease with common, disabling brain diseases of insidious onset has been overlooked. For example, lipohyalinosis, which has a pathological appearance of uncertain origin and is possibly responsible for some discrete lacunar infarcts, may be one end of a clinical spectrum of illness manifested by blood-brain barrier failure. CONCLUSIONS: Proof that blood-brain barrier failure is key to these conditions could provide a target for new treatments to reduce the effects of vascular disease on the brain and prevent cognitive decline and dementia.

Aging↗
PubMed2003

The impact of delays in computed tomography of the brain on the accuracy of diagnosis and subsequent management in patients with minor stroke.

OBJECTIVES: To determine the proportion of haemorrhagic strokes misdiagnosed as infarcts on computed tomography (CT) in patients with mild stroke, and the implications for health care. METHODS: Patients with mild stroke presenting as inpatients or outpatients four or more days after stroke to our stroke service (catchment population 500 000) were recruited prospectively. They underwent detailed clinical examination and brain imaging with CT and magnetic resonance imaging (MRI) on the day of presentation. CT and MR images were examined independently to identify infarct, primary intracerebral haemorrhage, haemorrhagic transformation, or non-vascular lesion. RESULTS: In 228 patients with mild stroke (median time from stroke to scan 20 days), primary intracerebral haemorrhage was identified by CT in two patients (0.9%; 95% confidence interval (CI), 0.1% to 3.1%) and MRI in eight (3.5%; 1.5% to 6.8%). Haemorrhagic transformation was identified by CT in three patients (1.3%; 0.1% to 5.6%) and MRI in 15 (6.6%; 3.7% to 10.6%). The earliest time primary intracerebral haemorrhage was not identified on CT was 11 days. CONCLUSIONS: CT failed to identify 75% of primary intracerebral haemorrhages, equivalent to 24 patients per 1000 (95% CI, 14 to 37) with mild strokes. To detect haemorrhages reliably, CT would need to have been performed within about eight days. Rapid access to neurovascular clinics with same day CT brain imaging is required to avoid inappropriate secondary prevention. Increased public awareness of the need to seek urgent medical attention after stroke should be encouraged. MRI should be considered in late presenting patients.

Adult↗
PubMed2003

Reliability of the variables in a new set of models that predict outcome after stroke.

OBJECTIVES: To provide valid predictions of outcome, the variables included in a prognostic model must be capable of reliable collection. The authors have recently reported a set of simple but rigorously developed models that predict outcome after stroke. The aim of this study was to establish the inter-rater reliability of the variables included in the models. METHODS: Inter-rater agreement was measured prospectively (between two clinicians; 92 patients) and retrospectively (between two auditors; 200 patients) and the validity of the data collected retrospectively was estimated by comparing them with data collected prospectively (195 patients). In the prospective study inter-rater agreement for urinary incontinence and for the variables of three other previously published models was also measured. The median difference (md) between ages and kappa statistics for other variables was calculated. RESULTS: For the model variables, prospective agreement ranged from good to excellent (age: md 0 years; living alone before the stroke kappa 0.84; pre-stroke functional independence kappa 0.67; normal verbal Glasgow Coma Scale score kappa 0.79; ability to lift both arms against gravity kappa 0.97; ability to walk unaided kappa 0.91) while retrospective agreement (age: md 0 years; kappa 0.55-0.92) and agreement between prospective and retrospective observers (age: md 0 years; kappa 0.49-0.78) was acceptable but less good. Prospective agreement was excellent for urinary incontinence (kappa 0.87) and variable for the other models (kappa 0.23-0.81) CONCLUSION: The variables included in these new simple models of outcome after stroke are capable of reliable collection, comparable to or better than that of the other predictive variables considered. When collected retrospectively, the model variables are likely to remain reliable and reasonably valid.

Aged↗
PubMed2003

Performance of a statistical model to predict stroke outcome in the context of a large, simple, randomized, controlled trial of feeding.

BACKGROUND AND PURPOSE: Statistical models to predict the outcome of stroke patients have several uses. Their utility depends on their predictive accuracy in patients other than those on whom they were developed (ie, external validity). We sought to test the external validity of some recently described models in patients enrolled in the FOOD (Feed Or Ordinary Diet) trial: a large randomized trial evaluating feeding policies in patients with stroke. METHODS: The predictive variables were collected during a telephone call to randomize the patient a median of 5 days after stroke onset. Patients were followed up 6 months later to establish their survival, functional status, and residence. Charts were plotted to demonstrate the discrimination and calibration of the models. RESULTS: The models performed well in the first 2955 patients enrolled and followed up in the FOOD trial. The area under the receiver operating characteristic curves varied between 0.78 and 0.81 (with 0.5 indicating no discrimination and 1.0 indicating perfect discrimination). The discrimination was marginally better for patients enrolled within the first day of stroke than later. The models tended to provide rather pessimistic predictions in all groups except those predicted to have a high likelihood of surviving free of dependency. CONCLUSIONS: As one might predict, the discriminatory power in the selected cohort of trial patients was marginally less good than in previously studied unselected cohorts used to test their external validity. These models provide a well-tested tool for stratification in trials, comparing outcomes in different cohorts and examining the additional predictive power of novel factors.

Aged↗