Table 2.

Exposure status and factor scores derived from exploratory and confirmatory factor analyses. Values are the estimate (95% CI) of the difference from unexposed for all subjects (n=997). *P-values include the two degree-of-freedom P-value comparing across all exposure groups (significance indicated by P<0.05) and pairwise comparisons of single or multiple exposures vs no exposure; significance of pairwise comparisons indicated in bold for P<0.025 (Bonferroni correction). The analysis used inverse probability of treatment weighting (IPTW) to account for imbalances across exposure categories amongst children actually tested. A separate model was fit for each factor score. The reference group for anaesthesia exposure was no exposure. CFA, confirmatory factor analysis; CI, confidence interval; EFA, exploratory factor analysis.

Characteristic	Factor 1		Factor 2		Factor 3		Factor 4		Factor 5
	Mean (95% CI)	P-value*	Mean (95% CI)	P-value*	Mean (95% CI)	P-value*	Mean (95% CI)	P-value*	Mean (95% CI)	P-value*
EFA		<0.001		0.407		0.962		0.729		0.063
Unexposed	Reference		Reference		Reference		Reference		Reference
Single	–0.08 (–0.26, 0.10)	0.40	0.13 (–0.06, 0.31)	0.18	0.01 (–0.22, 0.25)	0.91	–0.02 (–0.23, 0.19)	0.87	0.10 (–0.08, 0.28)	0.29
Multiple	–0.41 (–0.62, –0.19)	<0.001	0.04 (–0.14, 0.23)	0.64	–0.02 (–0.23, 0.19)	0.86	–0.07 (–0.24, 0.11)	0.44	–0.14 (–0.35, 0.06)	0.16
CFA		0.005		0.187		0.882		0.834		0.032
Unexposed	Reference		Reference		Reference		Reference		Reference
Single	–0.05 (–0.23, 0.14)	0.63	0.09 (–0.09, 0.28)	0.33	–0.01 (–0.24, 0.23)	0.95	–0.00 (–0.22, 0.22)	0.99	0.12 (–0.06, 0.29)	0.20
Multiple	–0.35 (–0.57, –0.13)	0.002	–0.10 (–0.29, 0.10)	0.32	0.04 (–0.16, 0.24)	0.67	0.05 (–0.13, 0.23)	0.59	–0.14 (–0.34, 0.05)	0.14