TABLE 1.

Baseline demographic, nutritional, and environmental characteristics (n = 674)¹

Variables	Placebo (n = 331)	Zinc (n = 343)	P2
Age (y)	8.9 ± 1.23	9.0 ± 1.2	0.58
Sex (% male)	49.2	50.7	0.70
Grade (y)	2.5 ± 1.0	2.5 ± 1.0	0.75
SES	0.1 ± 1.0	−0.1 ± 1.0	0.03
Maternal schooling (y)	4.6 ± 3.3	4.6 ± 3.4	0.85
BMI z score	0.3 ± 1.0	0.4 ± 1.0	0.26
Height-for-age z score	−1.2 ± 0.9	−1.2 ± 0.9	0.45
Stunted (%)4	14.5	14.0	0.85
Hemoglobin (g/dL)	13.8 ± 0.7	13.8 ± 0.8	0.75
Ferritin (μg/L)	46.9 (33.0, 63.0)5	47.1 (34.2, 62.7)	0.59
Iron deficiency (%)6	2.0	3.2	0.34
C-reactive protein (mg/L)	0.6 (0.3, 1.6)	0.6 (0.3, 1.7)	0.84
Evidence of inflammation (%)7	7.3	7.9	0.76
Child-reported stress frequency	82.2 ± 20.4	80.2 ± 18.4	0.18
Child-reported stress difficulty	104.8 ± 20.4	105.4 ± 20.5	0.69
CES-D total	16.6 ± 11.6	16.9 ± 11.5	0.77
Maternal distress (%)8	44.1	46.1	0.61
Parent-reported stress frequency	89.8 ± 15.9	89.5 ± 16.9	0.81
Parent-reported stress difficulty	130.4 ± 13.8	130.6 ± 14.7	0.87
Baseline high environmental stress (%)9	69.2	65.6	0.32

¹SES, socioeconomic status; CES-D, Center for Epidemiologic Studies–Depression Scale.

²t tests were used for comparison of means, and chi-square tests were used for comparison of proportions unless otherwise noted.

³Mean ± SD (all such values).

⁴Defined as height-for-age z score of less than −2 by using the World Health Organization 2007 reference (50).

⁵Median; interquartile range in parentheses (all such values); P values based on nonparametric Wilcoxon's test.

⁶Defined as ferritin concentrations <15 μg/L; the sample excluded any children with elevated C-reactive protein concentrations (ie, >5 mg/L); n = 307 for the placebo group and 316 for the zinc group.

⁷C-reactive protein concentrations >5 mg/L.

⁸Maternal depression total score ≥16.

⁹Defined as above the cutoff for any 2 of the following variables: maternal depression (≥16), child stress (above the median for frequency or difficulty), and parent stress (above the median for frequency or difficulty).