People who suffer a mini-stroke face a significant risk of a major stroke over the following week, research shows.
A review of research found one in 20 patients who have a transient ischaemic attack (TIA) will go on to have a stroke within a week.
The lowest risk of stroke was reported among patients treated as emergency cases in specialist stroke units.
The research, by the Oxford University Stroke Prevention Unit, is published by Lancet Neurology.
Previous research has produced conflicting results, with the seven-day stroke risk ranging from zero to 12.8%.
The Oxford team said a more definitive answer was required so that services could be planned accordingly.
They looked at 18 studies, featuring more than 10,000 patients, to come up with their seven-day risk figure of 5.2%.
Among people who received emergency treatment in specialist stroke units the risk fell to just 0.9%.
Variations in previous studies could be almost totally explained by differences in the way they were set up, the researchers found.
Writing in the journal, the researchers said: "These results support the argument that a TIA is a medical emergency and that urgent treatment in specialist units may reduce the risk of subsequent stroke.
"This is particularly relevant in the UK, where TIA services are patchy and there are substantial delays to TIA patients receiving appropriate treatments."
Joe Korner, of the Stroke Association, said: "Too often people ignore stroke symptoms if they don't last very long.
"Yet, a TIA is one of the only warning signs that a major stroke may be on its way and it is vital that anyone with a TIA is referred urgently to specialist services and for those at highest risk to be seen within 24 hours.
"This is not about brand new technology, or a costly intervention.
"It is about organising our services so that a TIA or minor stroke is always treated, and treated urgently. Indeed, previous studies have shown that quick treatment following a TIA can reduce the risk of a major stroke by 80%." ( BBC )