Table II.

Impact of Predictors on the Likelihood of Belonging to Each Trajectory Group, Relative to the Reference Group (Group 1, Less Severe and Stable)

Trajectory groups	Risk factor	Coefficient	SE	P
Group 2 (moderate and declining)	Age at diagnosis (months)	−0.00	0.03	.864
	Sex	−0.50	0.51	.327
	Income	−0.41	0.42	.324
	M-P-R DI standard score	−0.00	0.01	.686
	ADOS severity metric	−0.23	0.12	.057
Group 3 (severe and declining)	Age at diagnosis (months)	0.02	0.03	.581
	Sex	−0.85	0.59	.151
	Income	−1.00	0.46	.029
	M-P-R DI standard score	0.01	0.01	.300
	ADOS severity metric	0.09	0.15	.533
Group 4 (very severe and stable)	Age at diagnosis (months)	0.03	0.04	.536
	Sex	−10.13	107.96	.925
	Income	−0.33	0.68	.630
	M-P-R DI standard score	0.00	0.01	.7866
	ADOS severity metric	−0.32	0.19	.091

Note. M-P-R DI = Merrill-Palmer-Revised Scales of Development, Developmental Index; ADOS = Autism Diagnostic Observation Schedule.

A positive coefficient indicates a higher likelihood of being in the non-reference trajectory group.