• The ABCD and ABCD² scores are validated scales based on both prospective and retrospective data to assess patients' risk of stroke at 7 and 2 days after a TIA, respectively.  The biggest difference between the two is that the ABCD² Scale includes diabetes as a factor.

• ABCD Scale
• Age:  at least 60 = 1 point
• BP:  SBP > 140 and/or DBP > 90 = 1 point
• Clinical features:  unilateral weakness = 2 points; speech disturbance w/o weakness = 1 point;  any other neurologic  finding = 0 points.
• Duration:  at least 60 min. = 2 points; 10-59 min. = 1 point; < 10 min. = 0 points. 
• Score:  4 points = 1.1% risk;  5 points = 12.1% risk;  6 points = 31.4% risk.

• ABCD² Scale
• Age:  same as ABCD Scale
• BP:  same as ABCD Scale
• Clinical features:  same as ABCD Scale except "any other neurologic finding = 0 points" component is omitted.
• Duration:  same as ABCD Scale except  "< 10 min. = 0 points" component is omitted.
• Diabetes:  1 point
• Score:  4-5 points = 4% risk;  6-7 points = 8% risk;  0-3 points = 1% risk.

• Question = When considering sending a patient home prior to a thorough and appropriate TIA/stroke work-up, how low of a percent risk is acceptable?

References

• Lancet 2005; 366: 29-36.
• Lancet 2007; 369: 283-92.
• ACEP News, June 2008.