Table 2.

Performance and Rates of Impairment on Outcome Measures

Neurocognitive Outcome	Population		Subset		95% CI	Impaired (%)*	P	Adjusted P†
	Mean	SD	Mean	SD
Wechsler scales‡
Intelligence	100	15	96.0	15.78	93.9 to 98.0	22.9	.058687696	.176063
Working memory	100	15	96.0	14.46	93.5 to 98.4	24.3	.093919976	.18784
Processing speed	100	15	99.8	17.00	96.9 to 102.7	17.2	1.00	1.00
Conners' CPT§
Attentiveness	50	10	60.0	10.43	58.3 to 61.6	44.9	< .001	< .001
Response speed	50	10	71.7	19.17	68.7 to 74.8	63.5	< .001	< .001
Variability	50	10	58.7	13.61	56.6 to 60.9	46.2	< .001	< .001
Conners' parent report∥
Attention problems	50	10	53.2	14.19	51.4 to 55.1	24.8	.024548342	.073645
Impulsivity/hyperactivity	50	10	50.0	10.79	48.6 to 51.5	16.2	1.00	1.00
Hyperactivity index	50	10	50.2	11.65	48.7 to 51.8	15.8	1.00	1.00

Abbreviations: CPT, Continuous Performance Test; SD, standard deviation.

^‡Age-appropriate version of Wechsler intelligence scales (ie, Wechsler Preschool and Primary Scale of Intelligence–Revised,²¹ Wechsler Intelligence Scale for Children–Third Edition,²² or Wechsler Adult Intelligence Scale–Third Edition²³); lower scores reflect worse performance.

^§Conners' CPT²⁴: variability, SE of reaction time; attentiveness, D-prime; slow response speed, beta. Higher scores reflect worse performance. Low scores on beta can also reflect problem behavior, specifically impulsive response style; however, such abnormally fast responses were infrequent and not considered in impairment classification.

^∥Conners' Parent Rating Scale²⁴; higher scores reflect more problems.

^*Impairment defined as score falling > one SD below population mean.

^†P values adjusted using Holm-Bonferroni step-down method to account for multiple comparisons and reduce risk of type I error.²⁹