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Early prediction of stroke recovery

 

Clinical bottom line

The combination of clinical and magnetic resonance diffusion-weighted imaging provided good preditcion of stroke recovery shortly after admission to hospital.


Reference

EA Baird et al. A three-item scale for the early prediction of stroke recovery. Lancet 2001 357: 2095-2099.

Study

This study was carried out jointly between hospitals in Boston (which provided a training data set) and Melborne (which provided an evaluation data set.

Patients admitted to hospital in Boston with a diagnosis of acute ischaemic stroke, but not transient ischaemic attacks, were studied. They all had magnetic resonance diffusion-weighted imaging (MRDWI) within 49 hours of stroke onset. A National Instritues of Health Stroke Scale (NIHSS) was performed at the time of scanning, and a range of other demographic information collected.

The outcome was the Barthel score obtained one to three months after the stroke. Barthel scores has a maximum of 100, indicating full independence, and a score of 90 or above indicates persons who have near full functional independence and at most need help with one or two activities of daily living. The score of 90 was taken as good recovery from stroke, and anything less than this as poor recovery.

Of 347 admissions between 1993 and 1998, 66 in Boston fulfilled the criteria and had all data available. In melborne 63 patients conscutively studied between 1996 and 1999 had all data available.

All the factors were were examined first in univariate analysis to investigate any relationship between factor (age, for instance) and outcome. Those factors where there was some evidence of relationship were then studied in multivariate analysis in multiplelogistic regression modelling. For those factors where multivariate analysis showed a relation, different scores were given to different levels until the optimum diagnostic accuracy was obtained. This was then applied separately to Boston and Melborne patients.

Results

A three-item scale was devised (Table 1) with MRDWI lesion volume, NIHSS score and time from onset at scanning as the three components.

Table 1: Three item scale for prediction of stroke recovery

Factor

Points

Magnetic resonance diffusion-weighted imaging

<d14.1 mL

1

>14.1 mL

0

NIH stroke scale

<d 3

4

4 - 15

2

>15

0

Time from onset

<d 3 hours

0

3 - 6 hours

1

>6 hours

2

Total score

0 - 7

The performance of the score in predicting good recovery from stroke is shown in Figure 1 separately for Boston and Melborne patients at three levels of score. Overall, a score of 5 or more poduced a 90% chance of good recovery.

Figure 1: Performace of the score

Comment

This is a fine example of the development of a useful clinical scoring system for predicting an important outcome, that of good recovery from stroke. The methodology is typical of that we expect from good diagnostic of predictive scoring.