Table 1. Baseline Characteristics.

Characteristic	No. (%)
	Standard message	Tailored message	Control group	Total
Unique patients, No.	315	315	315	945
Age range, y
6-8	133 (42.2)	134 (42.5)	137 (43.5)	404 (42.8)
9-11	98 (31.1)	98 (31.1)	96 (30.5)	292 (30.9)
12-14	40 (12.7)	38 (12.1)	33 (10.5)	111 (11.7)
15-17	44 (14.0)	45 (14.3)	49 (15.6)	138 (14.6)
Sex
Female	152 (48.3)	167 (53.0)	174 (55.2)	493 (52.2)
Male	163 (51.7)	148 (47.0)	141 (44.8)	452 (47.8)
Race and ethnicity
American Indian or Alaska Native, non-Hispanic	0	1 (0.3)	0	1 (0.1)
Asian, non-Hispanic	10 (3.2)	4 (1.3)	5 (1.6)	19 (2.0)
Black, non-Hispanic	184 (58.4)	195 (61.9)	211 (67.0)	590 (62.4)
Black, Hispanic	3 (1.0)	1 (0.3)	2 (0.6)	6 (0.6)
Middle Eastern, non-Hispanic	0	1 (0.3)	0	1 (0.1)
Multiracial, non-Hispanic	21 (6.7)	15 (4.8)	15 (4.8)	51 (5.4)
Multiracial, Hispanic	1 (0.3)	1 (0.3)	1 (0.3)	3 (0.3)
Native Hawaiian and other Pacific Islander, Hispanic	0	0	1 (0.3)	1 (0.1)
White, non-Hispanic	82 (26.0)	73 (23.2)	71 (22.5)	226 (23.9)
White, Hispanic	5 (1.6)	10 (3.2)	3 (1.0)	18 (1.9)
Missing data, non-Hispanic	3 (1.0)	3 (1.0)	1 (0.3)	7 (0.7)
Missing data, Hispanic	6 (1.9)	11 (3.5)	5 (1.6)	22 (2.3)
Insurance
Public (ie, Medicaid)	280 (88.9)	275 (87.3)	252 (80.0)	807 (85.4)
Private	29 (9.2)	33 (10.5)	50 (15.9)	112 (11.9)
Self-pay	6 (1.9)	7 (2.2)	13 (4.1)	26 (2.8)
Childhood vaccine refusal
No past MMR and DTaP	2 (0.6)	4 (1.3)	3 (1.0)	9 (1.0)
Patient lifetime historical no-show rate, mean (SD)	0.14 (0.28)	0.18 (0.33)	0.17 (0.33)	0.16 (0.32)
Time since last WCC, mean (range)	17.0 (12.0-24.0)	17.2 (12.0-24.0)	16.9 (12.0-24.0)	17.0 (12.0-24.0)

Abbreviations: DTaP, diphtheria and tetanus toxoids and acellular pertussis; MMR, measles, mumps, and rubella; WCC, well child care.