Table 3.

Differences in 10-year outcome depending on initial hemoglobin and iron-fortified vs. low-iron formula

	Low 6-month hemoglobin				High 6-month hemoglobin
Outcome*	HB cut point (g/l)	n (%)†	Difference in score‡ (means)	Effect size (CI)§	HB cut point (g/l)	n (%)	Difference in score (means)	Effect size (CI)
IQ (WISC)	107	118 (24.0)	4.5 (89.1, 93.6)	0.34 (−0.01,0.68)‖	127	26 (5.5)	−12.9 (95.3, 82.4)	−0.96 (−1.60,−0.32)
Spatial memory (KABC subtest)	105	87 (17.0)	3.3 (91.2, 94.6)	0.31 (0.05,0.56)	127	26 (5.5)	−14.6 (104.1, 89.5)	−1.34 (−2.24,−0.44)
Arithmetic achievement (WRAT-R)	104	47 (9.4)	2.6 (88.1, 90.8)	0.22 (−0.04,0.46)	127	26 (5.5)	−10.7 (94.7, 84.0)	−0.85 (−1.38,−0.32)
Visual-motor integration (VMI)	105	87 (17.0)	4.1 (93.3, 97.4)	0.36 (0.10,0.63)	127	26 (5.5)	−19.3 (106.6, 87.3)	−1.36 (−2.00,−0.73)
Visual perception (VMI supplemental test)	104	47 (9.4)	3.4 (89.1, 92.5)	0.26 (−0.03,0.56)‖	130	23 (4.9)	−17.8 (100.9, 83.1)	−1.08 (−1.85,−0.31)
Motor coordination (VMI supplemental test)	104	47 (9.4)	3.9 (87.2, 90.9)	0.29 (−0.02,0.60)‖	127	26 (5.5)	−15.0 (100.2, 85.2)	−1.25 (−2.19,−0.32)

^*There were no significant differences on motor proficiency (Bruininks-Oseretsky short form).

^†Cell sizes vary because the empirically-derived cut points vary by test. At the low end, a higher HB cut point results in a larger cell size (more children had HB up to that value). At the high end, a higher HB cut point results in a smaller cell size (fewer children had HB above the higher cut point).

^‡Score for iron-fortified group minus score for low-iron group, expressed in points. Means adjusted for gestational age and gender for low-iron and iron-fortified groups are shown in ().

^§Effect size calculated as difference in score divided by overall standard deviation; CI, 95% confidence interval, shown in (). All differences for high HB and for low HB are statistically significant (p <0.05), i.e., CI does not include 0.

^‖Suggestive differences for low HB (p < 0.10).