Table 11.

Within-group and final between-groups multivariable regression models for school-age risk factor variables associated with case status.

Variable	Category	Within-group multivariable model		p value	Between-groups final multivariable model		p value
		Odds ratio (n = sample size)	95% confidence intervals		Odds ratio	95% confidence intervals
Demographics		n = 5,796			n = 4,303
Gender a	Female	1.00		<.001	1.00		.003
	Male	2.12	[1.59, 2.82]		1.69	[1.18, 2.42]
Maternal occupation a, b	Nonmanual	1.00		.014	NA
	Manual	1.50	[1.09, 2.06]
Home ownership a	Mortgaged/owned	1.00		<.001	1.00		.028
	Rented/other	1.85	[1.33, 2.57]		1.64	[1.07, 2.50]
Speech and language performance (concurrent)		n = 5,415
Difficulty pronouncing certain sounds a	No	1.00		<.001	1.00		<.001
	Yes	6.21	[4.63, 8.33]		5.59	[3.94, 7.94]
Nonword repetition c	Number correct	0.82	[0.78, 0.87]	<.001	0.82	[0.76, 0.87]	<.001
Literacy and learning (concurrent)		n = 4,238
Reading test c	Number correct	0.98	[0.96, 1.00]	.049	NA
School assessment: writing a	Achieved expected level	1.00		.027	NA
	Underachieved	2.04	[1.22, 3.41]
	Beyond expected	0.85	[0.44, 1.66]
Identified learning problems a	No	1.00		.003	NA
	Yes	2.03	[1.29, 3.20]
Other developmental variables (concurrent)		n = 4,802
Combined IQ score c	Number correct	0.88	[0.80, 0.98]	.016	NA
Auditory memory c	Number correct	0.93	[0.88, 0.98]	.006	NA
Spatial ability c	Number correct	NA			NA
Attention c	Number correct	NA			NA
Friendships c	Score	NA			NA
Suspected coordination problem a	No	1.00		<.001	1.00		.011
	Yes	2.45	[1.52, 3.95]		2.05	[1.21, 3.46]
Tympanostomy tubes fitted at any time a	No	1.00		<.001	1.00		.005
	Yes	2.36	[1.48, 3.77]		2.18	[1.30, 3.64]
Hearing impairment a	No	1.00		.023	1.00		.017
	Yes	1.76	[1.11, 2.80]		1.94	[1.16, 3.24]

Note. NA = not applicable, as the p value at this stage of the analysis was above the threshold of .5.

^a Categorical variable.

^b Supplemented with the father's social class when the mother's occupation was not available.

^c Continuous variable.