Short-term prognosis after transient ischemic attack and minor stroke

Short-term prognosis after transient ischemic attack and minor stroke 

Recent research has shown that the risk of stroke immediately after TIA or minor stroke is considerable (Giles and Rothwell 2007 Wu et al. 2007). However, this poses a challenge to clinical services because although the majority of patients will, by definition, have suffered a transient illness with no immediate major sequelae, an important minority are at risk of a major stroke in the short term. Prognostic tools have, therefore, been developed to identify patients at high (and low) risk in order to inform public education, aid effective triage to secondary care and direct secondary preventive treatment. 

Early risk of stroke after transient ischemic attack or minor stroke 

Patients with major stroke often report earlier short-lived neurological symptoms, and data from population-based studies and trials suggest that approximately 20% of patients with stroke have a preceding TIA (Rothwell and Warlow 2005). A similar proportion of major strokes are probably preceded by a minor stroke. However, the prospective estimation of risk after TIA or minor stroke is challenging, and in the past the risk has been considered to be low (approximately 1-2% at one week and 2-4% at one month) (Hankey et al. 1991 Gubitz et al. 1999 Gubitz and Sandercock 2000 Warlow et al. 2001). However, these risks are now considered underestimates because they were calculated from cohort studies and clinical trials in which patients were recruited some time after their initial event and patients who experienced subsequent stroke before recruitment were excluded (Rothwell 2003). 

Accurate estimation of the early risk of stroke after TIA or minor stroke requires particular study methods. First, potential patients must be recruited as rapidly as possible after the event so that strokes following very early after TIA are included. Second, patients should be assessed initially by an expert stroke physician to ensure that the diagnosis is made reliably and mimics are excluded. Third, follow-up should be in person and outcome events should be independently adjudicated to ensure correct identification of subsequent strokes. Lastly, patients should ideally be recruited from a defined population as opposed to a particular clinical setting in order to reduce selection bias. 

---