Characteristics of the Study Population at KPNC, January 2006–June 2017
| . | Study Population (N = 469 982), n (%) . |
|---|---|
| Age at study entrya | |
| 3 mo | 343 712 (73) |
| >3 mo to <1 y | 21 036 (4) |
| 1 to <2 y | 24 323 (5) |
| 2 to <3 y | 21 597 (5) |
| 3 to <4 y | 17 461 (4) |
| 4 to <5 y | 15 543 (3) |
| 5 to <6 y | 14 140 (3) |
| 6 to <7 y | 12 146 (3) |
| 7 y | 24 (0.0) |
| Born at KPNC hospital | 419 823 (89) |
| Year of birth | |
| 1999–2001 | 41 816 (9) |
| 2002–2004 | 63 366 (14) |
| 2005–2007 | 91 594 (19) |
| 2008–2010 | 91 512 (19) |
| 2011–2013 | 88 911 (19) |
| 2014–2016 | 92 783 (20) |
| Sex | |
| Female | 229 154 (49) |
| Male | 240 828 (51) |
| Race or ethnicityb | |
| White | 182 938 (39) |
| Asian or Pacific Islander | 112 142 (24) |
| Hispanic (regardless of race) | 111 165 (24) |
| Black | 28 673 (6) |
| American Indian or Alaskan native | 2260 (0) |
| Missing | 32 804 (7) |
| Pertussis status | |
| PCR-positive for pertussis | 738 (0.2) |
| . | Study Population (N = 469 982), n (%) . |
|---|---|
| Age at study entrya | |
| 3 mo | 343 712 (73) |
| >3 mo to <1 y | 21 036 (4) |
| 1 to <2 y | 24 323 (5) |
| 2 to <3 y | 21 597 (5) |
| 3 to <4 y | 17 461 (4) |
| 4 to <5 y | 15 543 (3) |
| 5 to <6 y | 14 140 (3) |
| 6 to <7 y | 12 146 (3) |
| 7 y | 24 (0.0) |
| Born at KPNC hospital | 419 823 (89) |
| Year of birth | |
| 1999–2001 | 41 816 (9) |
| 2002–2004 | 63 366 (14) |
| 2005–2007 | 91 594 (19) |
| 2008–2010 | 91 512 (19) |
| 2011–2013 | 88 911 (19) |
| 2014–2016 | 92 783 (20) |
| Sex | |
| Female | 229 154 (49) |
| Male | 240 828 (51) |
| Race or ethnicityb | |
| White | 182 938 (39) |
| Asian or Pacific Islander | 112 142 (24) |
| Hispanic (regardless of race) | 111 165 (24) |
| Black | 28 673 (6) |
| American Indian or Alaskan native | 2260 (0) |
| Missing | 32 804 (7) |
| Pertussis status | |
| PCR-positive for pertussis | 738 (0.2) |
Children born in 1999 entered the study on January 1, 2006, at 6 years of age, except for the few children born on January 1, 1999, who entered the study at 7 years of age; children born in 2000 entered the study on January 1, 2006, at 5 years of age, except for the few born on January 1, 2000, who entered the study at 6 years of age; and so on. Children born in or after October 2005 entered the study on their 3-month birthday.
The categories are mutually exclusive.