Carotiden en brein imaging verbeteren ABCD2 score

Nieuws - 26 okt. 2010

Carotid, brain imaging data add weight to ABCD2

26 October 2010

Adding findings from brain and carotid imaging to the ABCD2 score improves the risk stratification of patients with transient ischemic attack (TIA), shows a study in The Lancet Neurology.

The ABCD2 score is already in widespread clinical use, but in an accompanying commentary S Claiborne Johnston (University of California, San Francisco, USA) noted that additional information becomes available during further assessment of high-risk patients, "and it makes sense to incorporate this information into stroke-prediction rules."

For the study, Peter Kelly (Mater University Hospital, Dublin, Ireland) and colleagues assessed two possible extensions of the ABCD2, these being the ABCD3, which adds 2 points if patients have had another TIA within the previous 7 days, and the ABCD3-I, which adds 2 points if patients have at least 50% carotid stenosis and another 2 points if they have abnormal diffusion-weighted magnetic resonance imaging (MRI) findings.

The two extended scores were developed using data from a derivation sample of 2654 TIA patients. In this sample, the C-statistic for stroke within 7 days was higher for the ABCD3 and ABCD3-I scores than for the ABCD2 score, at 0.80 and 0.92 versus 0.71 (where 1.00 is perfect discrimination), respectively, indicating that the two new scores were superior for distinguishing between patients who did and did not suffer a stroke.

In a validation sample of a further 1232 patients, the ABCD3-I performed better than the ABCD2, with respective C-statistics of 0.71 versus 0.63 for stroke within 7 days of TIA, and was also superior for stroke within 28 and 90 days. However, the ABCD3 score was no better than the ABCD2, with a C-statistic of 0.64.

In the derivation sample, use of either new score resulted in improved reclassification of patients between stroke risk categories (low, medium, or high) from the ABCD2 score. This effect was not observed in the validation sample, however.

The team therefore concludes that the ABCD3 score should not be used without further validation, but says that "the ABCD3-I score might standardize and refine risk stratification, leading to improved clinical decision making with regard to the need for costly medical investigations, referral to specialist services, and admission to hospital."

Recently another attempt to expand the ABCD2 was published in the journal Stroke. This study added 3 points to the scale for patients with acute infarction on computed tomography or MRI, creating the ABCD2I score.

Johnston commented: "The timing of these studies creates a new problem: we now have two competing scores incorporating imaging into ABCD2, and no data to tell us which score is superior."

He concluded: "We will have to wait for a head-to-head comparison and, for now, confusion and uncertainty will probably reduce the use of both scores. It is difficult to imagine that carotid stenosis will not remain an important component in a score that includes imaging data, but it is to be hoped that the comparative study will emerge quickly so we can avoid an alphabet soup of potential scores."

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