Population based study of early risk of stroke after transient ischaemic attack or minor stroke: implications for public education and organisation of services
BMJ 2004; 328 doi: https://doi.org/10.1136/bmj.37991.635266.44 (Published 05 February 2004) Cite this as: BMJ 2004;328:326
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Re.: Population based study of early risk of stroke after transient ischaemic attack or minor stroke: implications for public education and organisation of services. AJ Coull, JK Lovett, PM Rothwell, on behalf of the Oxford Vascular Study. BMJ, doi:10.1136/bmj.37991.635266.44 (published 26 January 2004)
I have read the article by Coull, Lovett, and Rothwell reporting a high early risk of stroke after a TIA or minor stroke with interest. I am, however, surprised at the frequency of recurrences found in their patient population. I would like to know how recurrence within 7 days was discriminated from deteriorating stroke, e.g. if a sudden progression of neurological deficits was observed 24 hours after stroke onset, would it have been categorised as recurrent stroke?
In order to test if I could reproduce their results in a larger well- defined population of acute stroke patients I used a database, which was based on all patients admitted to an acute stroke unit within 6 hours of stroke onset covering the Copenhagen area from 1998 to 2001(1). I identified 333 patients that would be reasonably comparable to the presented patient population, 278 of our patients were diagnosed with TIA based on CT-scan and full neurological remission within 24 hours. Minor stroke – which I in the hope of identifying comparable patients defined as Scandinavian Stroke Scale Score > 56 -was found in 46 patients; 41 patients who were finally diagnosed with cerebral infarction and 5 patients who were diagnosed with intracerebral haemorrhage. Progression of neurological deficits occurring the first 72 hours after stroke onset was considered to be neurological deterioration, and progression occurring later than 72 hours after stroke onset was considered to be recurrence. Recurrence occurred in 3 patients (0.9 %) 72 hours – 7 days after stroke onset, in all 3 cases cerebral infarction was diagnosed. From 7 days – 1 month recurrence which led to medical attention occurred in 5 patients (1.5 %), 2 cases of cerebral infarction and 3 cases of TIA, and from 1 months to 3 months after stroke onset 5 patients (1.5%) were identified, 2 cases of cerebral infarction, 1 case of TIA, 1 case of ICH, and 1 case of stroke (CT scan not performed). When interviewed, 25 patients (7.5 %) reported symptoms of recurrence occurring from 7 days to 3 months after stroke onset. Progression within 72 hours occurred in 8 patients (2.4 %). Conclusively, when we look at medically confirmed recurrences it occurred in a total of 3.9 % in this patient population whereas self-reported symptoms of recurrence occurred in 8.4 % within the first 3 months after stroke onset. Within the first 7 days, recurrence occurred in 0.9 %, or 3.3 % if recurrence and progression are pooled. These levels are less than half of what is reported by Coull et al. Our data based on 333 patients confirm the previously accepted rates of recurrence after TIA/minor stroke so it is in our opinion premature to change the expected recurrence rates when informing patients after a TIA or minor stroke. I agree with the authors that further randomised controlled trials are needed which include patients in the first days and weeks after acute stroke in order to identify an evidence based treatment that will prevent early recurrent stroke.
Reference List
1. G Boysen, Brander T, Christensen H, Truelsen T, Gideon R. Homocysteine and risk of recurrent stroke. Stroke 2003; 34:1258-1261.
Competing interests: None declared
Competing interests: No competing interests
Editor - recent studies have reshaped our understanding of the pathophysiology and diagnosis of transient ischaemic attacks (TIAs), and Coull et al have added valuable information to the important developments [1].
In a recent study by Inatomi et al, 129 patients with TIA were scanned using MRI including diffusion-weighted imaging (DWI), which is a more sensitive and specific tool in evaluating acute ischaemic changes compared to conventional CT or MR imaging [2]. The study found that 57/129 (44%) TIA patients had DWI abnormalities, and the presence of TIA-related DWI abnormalities were associated with prolonged duration of symptoms (over 30 minutes), and disturbance of higher brain function [2]. Although the absolute value of DWI in assessing acute ischaemic changes is yet to be elucidated, this study does challenge the traditional belief that TIAs are 'benign' and not associated with permanent neuronal damage. A related editorial by Warach and Kidwell proposed a redefinition of TIA, taking into account findings from newer neuroimaging techniques such as DWI (for evidence of brain infarction) as well as clinical symptoms and signs [3]. However, since the majority of hospitals do not have access to these newer neuroimaging techniques, stroke physicians will no doubt continue to rely on the clinical history and examination to diagnose TIA in the foreseeable future.
The results reported by Coull et al helps to emphasise that TIAs and minor strokes should be managed aggressively and with urgency. Investigations into the aetiology of the cerebral event and appropriate secondary preventive measures (e.g. antiplatelet therapy) should be implemented as soon as possible in order to reduce the risk of future strokes. Stroke physicians and general practitioners should pay careful attention to the reported estimated risk of recurrent stroke of 8% in the first seven days after a TIA, and 11.5% after a minor stroke.
TIAs can be regarded as one end of the spectrum of acute cerebrovascular syndrome, and should be treated as such. Since over a third of all stroke patients arrive in hospital within three hours of symptom onset [4], the differentiation between a TIA and a stroke becomes less meaningful in the emergency department setting. Acute presentations of neurological deficits of sudden onset should all be classed as 'brain attacks' and be managed as a medical emergency, including consideration for thrombolysis and admission to an acute stroke unit for early physiological monitoring and multidisciplinary therapy provided by a specialist stroke team.
In some European countries such as Germany, patients presenting with TIA are admitted as inpatients for urgent investigations and treatment. In the UK, many patients with TIA still do not have access to early assessment by stroke specialists or investigations such as carotid duplex and echocardiography. Time has come to improve our understanding of TIAs and minor strokes, and start taking these conditions more seriously.
References:
1. Coull AJ, Lovett JK, Rothwell PM. Population based study of early risk of stroke after transient ischaemic attack or minor stroke: implications for public education and organisation of services. BMJ 2004;328:326-9.
2. Inatomi Y, Kimura K, Yonehara T, Fujioka S, Uchino M. DWI abnormalities and clinical characteristics in TIA patients. Neurology 2004;62:376-80.
3. Warach S, Kidwell CS. The redefinition of TIA. The uses and limitations of DWI in acute ischemic cerebrovascular syndromes. Neurology 2004;62:359-60.
4. Harraf F, Sharma AK, Brown MM, Lees KR, Vass RI, Kalra L. A multicentre observational study of presentation and early assessment of acute stroke. BMJ 2002;325:17-22.
Competing interests: None declared
Competing interests: No competing interests
Rates of Early Recurrence of Cerebrovascular Events in Glasgow's East End
Editor - Coull et al pointed out that although a good deal of work has been carried out highlighting the risk of poor outcomes with delayed assessment and investigation after an acute stroke event, there is little similar information following a transient ischaemic attack (TIA)[1]. Hence, there is little evidence behind the current recommendations regarding the time within which patients should undergo specialist assessment following a suspected TIA, traditionally perceived as a relatively benign pathology [2, 3, 4]. The high early recurrence rates reported by Coull et al in their prospective study prompted us to audit the outcomes of patients attending our TIA clinics [1]. We conducted a retrospective analysis of all the new referrals over a 6 month period to the TIA clinics based in two hospitals in the east end of Glasgow. Our audit included examining clinic letters for reports of recurrent symptoms after the index referral.
Of 372 new referrals to the clinics 37 did not attend, 130 had a non- cerebrovascular diagnosis, and, a total of 205 were deemed to have suffered a probable or definite new stroke or TIA, 84 and 121 respectively. Patients were referred early with a median time from symptom to referral of 2 days and a median follow up period of 28 days. There were 19 documented recurrent cerebrovascular events in this group giving a crude recurrence rate of 9% (95% confidence interval 5%-13%) of which 10 cases (5%, CI 2%-8%) were known to have occurred within one week and 15 (7%, CI 4%-11%) within one month.
Although on initial examination these figures are lower than those reported by Coull et al [1], examining the data for those presenting with a TIA, since more of our minor stroke patients are likely to have been admitted as only a weekly TIA/mini stroke service is offered, compared to the daily service provided in Oxford, the following results are obtained: - 17 recurrent events from 121 TIAs (14%, CI 8%-20%) in total with 7 cases (6%, CI 1%-10%) within one week and 13 (11%, CI 8%-20%) within one month. Sensitivity analyses for missing patients did not substantially alter the results. These results are similar to the 11.5%(CI 4.8%-18.2%) quoted by Coull et al at 1 month [1].
It is unclear whether secondary prevention can reduce this early recurrence. However there is good evidence for the benefit of early carotid endarterectomy in appropriate patients following a stroke or TIA, and for early medical therapy following a stroke event. Hopefully the lack of evidence for early prevention after TIA is only temporary. We agree with Coull et al that future research is required to identify the medical and organisational strategies that will best reduce the risk of early recurrent cerebrovascular events [1].
REFERENCES:
1. Coull AJ, Lovett JK, Rothwell PM. Population based study of early risk of stroke after transient ischaemic attack or minor stroke: implications for public education and organisation of services. BMJ 2004;328: 326-30. (7 February.)
2. Intercollegiate Working Party for Stroke. National clinical guidelines for stroke. London: Royal College of Physicians, 2000.
3. Scottish Intercollegiate Guidelines Network. SIGN guidelines: management of patients with stroke. Edinburgh: SIGN, 1997.
4. Department of Health. National service framework for older people. London: Department of Health, 2001.
Competing interests: None declared
Competing interests: No competing interests