Table 1. Study Sample Characteristics.
| Characteristic | No. (%) | Standardized differencea | ||
|---|---|---|---|---|
| Overall (N = 659 286) | SARS-CoV-2 viral test result | |||
| Negative (n = 599 393) | Positive (n = 59 893) | |||
| Age at cohort entrance, mean (SD), y | 8.1 (5.7) | 7.9 (5.7) | 9.4 (5.9) | .26 |
| Age at cohort entrance, y | ||||
| <1 | 58 660 (8.9) | 54 133 (9.0) | 4527 (7.6) | .25 |
| 1-4 | 195 269 (29.6) | 182 252 (30.4) | 13 017 (21.7) | |
| 5-11 | 217 684 (33.0) | 197 669 (33.0) | 20 015 (33.4) | |
| 12-15 | 104 470 (15.8) | 92 552 (15.4) | 11 918 (19.9) | |
| 16-<21 | 83 203 (12.6) | 72 787 (12.1) | 10 416 (17.4) | |
| Follow-up during outcome assessment period, mean (SD), mo | 4.7 (0.7) | 4.7 (0.7) | 4.6 (0.7) | .13 |
| Sex | ||||
| Female | 311 164 (47.2) | 281 998 (47.0) | 29 166 (48.7) | .03 |
| Male | 348 091 (52.8) | 317369 (53.0) | 30 722 (51.3) | |
| Race and ethnicityb | ||||
| Non-Hispanic Asian or Pacific Islander | 28 832 (4.4) | 27 108 (4.5) | 1724 (2.9) | .19 |
| Non-Hispanic Black | 104 618 (15.9) | 92 497 (15.4) | 12 121 (20.2) | |
| Hispanic | 103 148 (15.6) | 91 896 (15.3) | 11 252 (18.8) | |
| Multiple races | 26 832 (4.1) | 24 485 (4.1) | 2347 (3.9) | |
| Non-Hispanic White | 342 935 (52.0) | 314 782 (52.5) | 28 153 (47.0) | |
| Other race or unknown | 52 921 (8.0) | 48 625 (8.1) | 4296 (7.2) | |
| Institution | ||||
| Site A | 32 922 (5.0) | 31 987 (5.3) | 935 (1.6) | .29 |
| Site B | 83 726 (12.7) | 76 387 (12.7) | 7339 (12.3) | |
| Site C | 41 616 (6.3) | 39 403 (6.6) | 2213 (3.7) | |
| Site D | 125 243 (19.0) | 110 400 (18.4) | 14 843 (24.8) | |
| Site E | 103 830 (15.9) | 94 557 (15.8) | 10 273 (17.2) | |
| Site F | 134 054 (20.3) | 121 725 (20.3) | 12 329 (20.6) | |
| Site G | 97 447 (14.8) | 88 134 (14.7) | 9313 (15.5) | |
| Site H | 39 448 (6.0) | 36 800 (6.1) | 2648 (4.4) | |
| Chronic conditions | ||||
| None | 462 248 (70.1) | 419 152 (69.9) | 43 096 (72.0) | .06 |
| Noncomplex | 104 144 (15.8) | 94 647 (15.8) | 9497 (15.9) | |
| Complex | 92 894 (14.1) | 85 594 (14.3) | 7300 (12.2) | |
| Time period of cohort entrance | ||||
| March 2020-June 2020 | 55 753 (8.5) | 53 590 (8.9) | 2163 (3.6) | .53 |
| July 2020-October 2020 | 146 054 (22.2) | 139 587 (23.3) | 6467 (10.8) | |
| November 2020-February 2021 | 161 986 (24.6) | 138 120 (23.0) | 23 866 (39.8) | |
| March 2021-June 2021 | 129 171 (19.6) | 120 262 (20.1) | 8909 (14.9) | |
| July 2021-October 2021 | 166 322 (25.2) | 147 834 (24.7) | 18 488 (30.9) | |
| Obesity | 164 895 (25.0) | 148 499 (24.8) | 16 396 (27.4) | .06 |
| Admitted to intensive care unit | 14 521 (2.2) | 13 847 (2.3) | 674 (1.1) | .09 |
| Test location | ||||
| Emergency department | 125 797 (19.1) | 114 227 (19.1) | 11 570 (19.3) | .19 |
| Inpatient | 39 513 (6.0) | 37 857 (6.3) | 1656 (2.8) | |
| Outpatient clinic | 162 138 (24.6) | 148 371 (24.8) | 13 767 (23.0) | |
| Outpatient testing facility | 332 813 (50.3) | 298 918 (49.9) | 32 895 (54.9) | |
a
For continuous variables, the standardized difference was computed as the difference in means divided by the pooled standard deviation. For categorical variables, the standardized difference was calculated from a distance matrix on a vector difference between categories, normalized by a covariate matrix calculated from the rates of categories in each of the 2 groups.
b
Race and ethnicity data were collected by self-report. The other race category includes patients whose race was categorized as American Indian or Alaska Native (1088 patients) or other (12 004 patients).