Table 2. Prevalence of AA by Year, Age, Sex, Race and Ethnicity, and Institution.
| Category | No. (%) | |
|---|---|---|
| Prevalence, denominator population | AA cohort (prevalence, %) | |
| Overall | 5 409 919 | 5801 (0.11) |
| Calendar year | ||
| 2009 | 1 069 674 | 404 (0.04) |
| 2010 | 1 146 812 | 532 (0.05) |
| 2011 | 1 213 796 | 591 (0.05) |
| 2012 | 1 262 563 | 618 (0.05) |
| 2013 | 1 284 340 | 715 (0.06) |
| 2014 | 1 336 367 | 855 (0.06) |
| 2015 | 1 398 651 | 972 (0.07) |
| 2016 | 1 474 138 | 1081 (0.07) |
| 2017 | 1 521 833 | 1234 (0.08) |
| 2018 | 1 523 480 | 1251 (0.08) |
| 2019 | 1 525 325 | 1262 (0.08) |
| 2020 | 1 465 308 | 942 (0.06) |
| Age, y | ||
| 0 | 1 386 620 | 24 (<0.01) |
| 1 | 1 190 712 | 156 (0.01) |
| 2 | 1 039 495 | 365 (0.04) |
| 3 | 946 301 | 504 (0.05) |
| 4 | 903 014 | 612 (0.07) |
| 5 | 873 733 | 656 (0.08) |
| 6 | 821 140 | 751 (0.09) |
| 7 | 783 673 | 732 (0.09) |
| 8 | 758 231 | 717 (0.09) |
| 9 | 740 902 | 710 (0.10) |
| 10 | 730 241 | 676 (0.09) |
| 11 | 732 614 | 687 (0.09) |
| 12 | 723 896 | 660 (0.09) |
| 13 | 718 831 | 622 (0.09) |
| 14 | 718 058 | 643 (0.09) |
| 15 | 699 624 | 593 (0.08) |
| 16 | 667 465 | 552 (0.08) |
| 17 | 600 055 | 459 (0.08) |
| Sex | ||
| Male | 2 748 160 | 2542 (0.09) |
| Female | 2 660 917 | 3259 (0.12) |
| Race and ethnicity | ||
| Asian | 209 237 | 359 (0.17) |
| Black | 882 687 | 1094 (0.12) |
| Hispanic | 594 553 | 1348 (0.23) |
| White | 3 005 040 | 2362 (0.08) |
| Institution | ||
| CHOP | 1 297 281 | 1738 (0.13) |
| Colorado | 1 033 094 | 1367 (0.13) |
| Nationwide | 884 725 | 705 (0.08) |
| Nemours, Delaware | 583 034 | 581 (0.10) |
| Seattle | 646 369 | 822 (0.13) |
Abbreviations: AA, alopecia areata; CHOP, Children’s Hospital of Philadelphia, Colorado, Children’s Hospital Colorado; Nationwide, Nationwide Children’s Hospital; Nemours, Nemours Children’s Health System; Seattle, Seattle Children’s Hospital.