Table 4.

AOW, nonverbal IQ, and symptom scores in ASD versus non-ASD, as well as between-groups comparisons

		ASD females		Non-ASD females	95% CI for the difference		ASD males		Non-ASD males	95% CI for the difference
	n	Mean (SD)	n	Mean (SD)		n	Mean (SD)	n	Mean (SD)
Available case analysis (n ≤ 490)
AOW (mo)	84	15.1 (4.7)	29	14.9 (3.8)	(− 1.7 to 2.1)	292	14.6 (4.2)	85	13.4 (2.4)	(0.6 to 2.0) **
Nonverbal IQ	53	99.4 (13.9)	23	98.2 (14.7)	(− 5.9 to 8.2)	201	103.0 (18.6)	62	101.9 (18.4)	(− 4.2 to 6.4)
SCQ total	32	15.6 (7.5)	17	7.0 (6.3)	(4.3 to 12.9) ***	111	16.4 (7.2)	55	8.4 (5.3)	(6.0 to 10.0) ***
ADI-R nonverbal total	28	20.7 (9.7)	8	7.4 (7.1)	(5.8 to 20.8) **	90	22.4 (8.7)	15	14.3 (10.4)	(3.2 to 13.1) **
SRS total	51	93.5 (26.4)	21	61.0 (26.5)	(18.9 to 46.2) ***	196	85.1 (29.0)	67	65.7 (24.8)	(11.7 to 27.2) ***
Multiple-imputation analysis (n = 393)
AOW (mo)	63	14.7 (4.6)	24	15.0 (3.7)	(− 2.5 to 1.7)	233	14.6 (3.6)	73	13.3 (2.3)	(0.6 to 2.0) ***
Nonverbal IQ	63	99.6 (17.8)	24	98.6 (15.2)	(− 6.6 to 8.6)	233	102.2 (25.9)	73	103.0 (19.9)	(− 6.5 to 5.0)
SCQ total	63	14.5 (7.2)	24	8.4 (6.9)	(2.8 to 9.4) ***	233	15.1 (6.1)	73	9.7 (5.6)	(3.9 to 6.9) ***
ADI-R nonverbal total	63	21.5 (19.7)	24	9.2 (22.1)	(1.5 to 23.1) *	233	22.5 (16.0)	73	13.5 (20.9)	(3.5 to 14.5) **
SRS total	63	91.7 (24.2)	24	63.7 (25.9)	(16.3 to 39.5) ***	233	84.3 (26.8)	73	66.8 (24.2)	(10.6 to 24.4) ***

ASD autism spectrum disorder, AOW age for onset of independent walking. Measures of autistic symptom severity: SCQ Social Communication Questionnaire, ADI-R Autism Diagnostic Interview-Revised, SRS Social Responsiveness Scale. Results based on available case analysis of the main sample and multiple imputation of n = 393 participants with data on at least one measure of symptom severity. SD standard deviation, CI confidence interval, p p-value

*p < .05; **p < .01; ***p < .001 for independent samples t-tests