Adult cognitive outcomes in phenylketonuria: explaining causes of variability beyond average Phe levels

Table 4 Regression analyses predicting cognitive outcomes from Phe variation (SD) and Phe average entered either at the same step (forward method; set A) or at different steps (set b). Phe variation and Phe average are computed across the life-span. Coefficient and p refer to best model

Dependent variable		R2	Adj R2	Predictors	stand β	p	R2 change
Analysis-A
Full IQ	Step 1	0.16	0.14	Education	.28	.01
	Step 2	0.39	0.37	Phe SD	−0.5	<.001
				Phe average	–	–
Mean z-score	Step 1	0.09	0.08	Education	−19	.09
	Step 2	0.42	0.39	Phe SD	.46	<.001
				Phe average	.23	.049
Analysis B
Full IQ	Step 1	0.05	0.03	Phe average	−.03	n.s.	–
Full IQ	Step 2	0.32	0.29	Phe SD	−.55	<.001	0.27
Mean z-score	Step 1	0.16	0.14	Phe average	.22	.06	–
Mean z-score	Step 2	0.39	0.36	Phe SD	.51	<.001	0.23

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