Table 1. General Characteristics of Participants.
| General characteristicsa | Participants, No. (%) | P value | |
|---|---|---|---|
| 2019 | 2020 | ||
| Total No. | 48 443 (100.0) | 44 216 (100.0) | |
| Age, mean (SD), y | 15.0 (1.7) | 15.1 (1.7) | <.001b |
| BMI, mean (SD) | 21.4 (3.5) | 21.6 (3.7) | <.001b |
| Physical exercise, mean (SD), d/wk | 2.0 (2.1) | 1.9 (2.1) | <.001b |
| Sedentary time, mean (SD), h/d | |||
| For study | 6.6 (3.7) | 6.0 (3.3) | <.001b |
| For leisure | 3.3 (2.2) | 4.2 (2.7) | <.001b |
| Sleep time, mean (SD), h/d | 7.0 (1.5) | 6.9 (1.5) | <.001b |
| Sex | |||
| Male | 24 917 (51.3) | 23 103 (52.5) | .50 |
| Female | 23 526 (48.7) | 21 113 (47.5) | |
| Economic level | |||
| High | 18 992 (39.6) | 17 381 (40.3) | .32 |
| Middle | 23 376 (48.1) | 21 228 (47.5) | |
| Low | 6075 (12.3) | 5607 (12.2) | |
| Educational level of father | |||
| Unknown, missing, below middle school | 23 775 (48.3) | 17 957 (39.7) | <.001c |
| High school | 7385 (14.8) | 7519 (16.2) | |
| College or greater | 17 283 (36.8) | 18 740 (44.0) | |
| Educational level of mother | |||
| Unknown, missing, below middle school | 23 050 (47.0) | 16 925 (37.5) | <.001c |
| High school | 8637 (17.7) | 8941 (19.6) | |
| College or greater | 16 756 (35.3) | 18 350 (42.9) | |
| Scholastic performance | |||
| Highest | 6464 (13.1) | 5625 (12.7) | .12 |
| Middle high | 12 407 (25.5) | 11 157 (25.5) | |
| Middle | 14 697 (30.4) | 13 496 (30.4) | |
| Middle low | 10 519 (21.8) | 9995 (22.5) | |
| Lowest | 4356 (9.1) | 3943 (8.9) | |
| Subjective health status | |||
| Very healthy | 12 911 (26.4) | 12 283 (27.3) | .07 |
| Healthy | 21 444 (44.2) | 19 131 (43.4) | |
| Normal | 10 749 (22.4) | 9742 (22.2) | |
| Unhealthy | 3339 (70.) | 3060 (7.1) | |
| Stress level | |||
| No stress | 1805 (3.6) | 1597 (3.5) | <.001c |
| Little | 7579 (15.4) | 8128 (18.2) | |
| A little | 20 090 (41.6) | 19 907 (45.2) | |
| Severe | 13 605 (28.3) | 11 231 (25.7) | |
| Very severe | 5364 (11.1) | 3353 (7.5) | |
| Sadness or despair | 13 232 (27.5) | 10 609 (23.9) | <.001c |
| Thinking of suicide | 6092 (12.6) | 4517 (10.1) | <.001c |
| Plan of suicide | 1721 (3.5) | 1396 (3.1) | .002c |
| Suicide attempt | 1283 (2.6) | 760 (1.7) | <.001c |
Abbreviation: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared).
a
Estimated mean or prevalence adjusted recommended weighted value.
b
Linear regression analysis with complex sampling.
c
χ2 test with Rao-Scott correction.