TY - JOUR T1 - Interobserver Reliability of Baseline Noncontrast CT Alberta Stroke Program Early CT Score for Intra-Arterial Stroke Treatment Selection JF - American Journal of Neuroradiology JO - Am. J. Neuroradiol. SP - 1046 LP - 1049 DO - 10.3174/ajnr.A2942 VL - 33 IS - 6 AU - A.C. Gupta AU - P.W. Schaefer AU - Z.A. Chaudhry AU - T.M. Leslie-Mazwi AU - R.V. Chandra AU - R.G. González AU - J.A. Hirsch AU - A.J. Yoo Y1 - 2012/06/01 UR - http://www.ajnr.org/content/33/6/1046.abstract N2 - BACKGROUND AND PURPOSE: Early ischemic changes on pretreatment NCCT quantified using ASPECTS have been demonstrated to predict outcomes after IAT. We sought to determine the interobserver reliability of ASPECTS for patients with AIS with PAO and to determine whether pretreatment ASPECTS dichotomized at 7 would demonstrate at least substantial κ agreement. MATERIALS AND METHODS: From our prospective IAT data base, we identified consecutive patients with anterior circulation PAO who underwent IAT over a 6-year period. Only those with an evaluable pretreatment NCCT were included. ASPECTS was graded independently by 2 experienced readers. Interrater agreement was assessed for total ASPECTS, dichotomized ASPECTS (≤7 versus >7), and each ASPECTS region. Statistical analysis included determination of Cohen κ coefficients and concordance correlation coefficients. PABAK coefficients were also calculated. RESULTS: One hundred fifty-five patients met our study criteria. Median pretreatment ASPECTS was 8 (interquartile range 7–9). Interrater agreement for total ASPECTS was substantial (concordance correlation coefficient = 0.77). The mean ASPECTS difference between readers was 0.2 (95% confidence interval, −2.8 to 2.4). For dichotomized ASPECTS, there was a 76.8% (119/155) observed rate of agreement, with a moderate κ = 0.53 (PABAK = 0.54). By region, agreement was worst in the internal capsule and the cortical areas, ranging from fair to moderate. After adjusting for prevalence and bias, agreement improved to substantial or near perfect in most regions. CONCLUSIONS: Interobserver reliability is substantial for total ASPECTS but is only moderate for ASPECTS dichotomized at 7. This may limit the utility of dichotomized ASPECTS for IAT selection. AISacute ischemic strokeASPECTSAlberta Stroke Program Early CT ScoreCIconfidence intervalIATintra-arterial stroke therapyIQRinterquartile rangeM1MCA stemM2MCA second-order branchPABAKprevalence-adjusted, bias-adjusted kappaPAOproximal artery occlusion ER -