TABLE 1

Study Population by IOE

IOE, n = 236No IOE, n = 11 098P
Patient characteristics
 Race, % (n)<.001
  White69.1 (163)34.8 (3865)
  African American15.7 (37)44.4 (4925)
  Asian American0 (0)2.9 (323)
  Other13.6 (32)13.8 (1532)
  Unknown1.7 (4)4.1 (453)
 Ethnicity, % (n).01
  Hispanic11.0 (26)12.5 (1387)
  Non-Hispanic88.6 (209)83.5 (9265)
  Unknown0.4 (1)4.0 (446)
 Insurance, % (n)<0.001
  Medicaid97.9 (231)66.7 (7404)
  Private1.4 (4)32.8 (3645)
  Other or unknown0.4 (1)0.4 (49)
 Birth wt, g, mean3048.43353.1<.001b
 Gestational age, wk, mean38.038.2.14b
 Complex chronic condition, % (n)16.5 (39)15.9 (1762).78a
 Child sex male, % (n)50.0 (118)51.9 (5763).56a
 Area-level poverty, %17.515.9.02a
 Metropolitan versus nonmetropolitan zip code, % (n)97.5 (230)95.2 (10 566).11a
Outcomes
 WCC adherence, % (n)
  Birth to 12 mo25.9 (61)54.7 (6068)<.001a
  4–12 mo39.8 (94)58.2 (6459)<.001a
  12–24 mo41.5 (98)57.5 (6377)<.001a
 ≥1 WCC gap, % (n)42.8 (101)27.8 (3085)<.001a
 No. nonroutine visits, median (IQR)9.5 (7–14)11 (8–15).005b
 On-time immunization status,c % (n)83.9 (198)85.8 (9526).40a
 Lead screening at 1 y, % (n)62.3 (147)52.9 (5875).004a
  • Totals for some variables may not add to 100% because of missing data. IQR, interquartile range.

  • a χ2 P value.

  • b Wilcoxon rank test P value.

  • c Receipt of the combined 7-vaccine series (4:3:1:3:3:1:4) by age 2 y per the Centers for Disease Control and Prevention, which includes ≥4 doses of the diphtheria-tetanus-acellular pertussis vaccine, ≥3 doses of the poliovirus vaccine, ≥1 dose of the measles-containing vaccine, ≥3 or ≥4 doses (depending on the product type) of the Haemophilus influenzae type b vaccine, ≥3 doses of the hepatitis B vaccine, ≥1 dose of the varicella vaccine, and ≥4 doses of the pneumococcal conjugate vaccine.