TABLE 2

Follow-up and ASD Diagnosis in Children Born Between 2011 and 2014 to Women Who Were Unvaccinated and Vaccinated With Tdap During Pregnancy

Unvaccinated n = 42 916Vaccinated n = 39 077Pa
Follow-up characteristics
 Total follow-up time (1000 person y)190.74150.56
Length of follow-up, y
 Mean (SD)4.44 (1.18)3.85 (1.29)<.0001
 Median4.603.50
 Q1, Q33.7, 5.32.9, 4.9
 Range(1.2–6.5)(1.2–6.5)
Reasons for ending follow-up
 Termination of KPSC membership, n (%)6508 (15.2)5242 (13.4)<.0001
 End of study (June 30, 2017), n (%)35 636 (83.0)33 266 (85.1)<.0001
 ASD diagnosis, n (%)772 (1.8)569 (1.5).0008
ASD diagnosis prevalence by birth y, n (%)
 2011218 of 11 202 (1.9)143 of 8063 (1.8).3836
 2012282 of 15 146 (1.9)80 of 5407 (1.5).0666
 2013206 of 12 017 (1.7)145 of 8725 (1.7).7729
 201466 of 4551 (1.5)201 of 16 882 (1.2).1611
ASD diagnosis age, n (%), y772 (100)569 (100)<.0001
 197 (12.6)116 (20.4)
 2337 (43.7)251 (44.1)
 3 or 4314 (40.7)178 (31.3)
 5 or 624 (3.1)24 (4.2)
  • —, not applicable.

  • a P values were calculated by using χ2 or Student’s t test.