Table 4

Level of agreement between modalities (singly and in combination) and the reference standard and with each other determined using unweighted κ statistic

Modalities compared κ (95% CI)
CTA with IADSA per patient (PP)0.72 (0.59–0.85)
MRA with IADSA PP0.71 (0.58–0.85)
TCD with IADSA PP0.66 (0.52–0.81)
CTA with MRA PP0.73 (0.59–0.86)
CTA with TCD PP0.60 (0.45–0.75)
MRA with TCD PP0.66 (0.51–0.81)
CTA with MRA per aneurysm0.69 (0.56–0.81)
CTA with TCD per aneurysm0.44 (0.27–0.61)
MRAwith TCD per aneurysm0.50 (0.32–0.68)
CTA+TCD with IADSA PP4-150 0.84 (0.72–0.95)
MRA+TCD with IADSA PP4-150 0.79 (0.69–0.94)
CTA+MRA with IADSA PP4-150 0.83 (0.71–0.94)
  • κ⩽0.20 indicates poor agreement, of 0.21–0.40 fair agreement, of 0.41–0.60 moderate agreement, of 0.61–0.80 good agreement, and of >0.80 very good agreement.

  • 4-150 These results apply where the non-invasive tests agreed with each other. Where they disagreed the result was classified as “uncertain” and not included in the calculation of κ.