Table 1.
Characteristics of the study group for the total population and by the COVID-19 pandemic.
| Variable | Entire Study Group N (%) |
Before the Pandemic N (%) |
During the Pandemic N (%) |
Size Effect | p ^ | |
|---|---|---|---|---|---|---|
| Sex | Female | 15,743 (78.2) | 7887 (77.4) | 7856 (78.9) | 6.69 * | 0.010 |
| Male | 4396 (21.8) | 2300 (22.6) | 2096 (21.1) | |||
| Age M ± SD | 22.6 ± 3.6 | 22.4 ± 3.0 | 22.7 ± 4.1 | 0.083 # | <0.001 | |
| Year of study | I | 5504 (27.3) | 2180 (21.4) | 3324 (33.4) | 458.52 * | <0.001 |
| II | 3600 (17.9) | 2106 (20.7) | 1494 (15.0) | |||
| III | 3761 (18.7) | 2173 (21.4) | 1588 (16.0) | |||
| IV | 3119 (15.5) | 1624 (15.9) | 1495 (15.0) | |||
| V | 2885 (14.3) | 1530 (15.0) | 1355 (13.6) | |||
| VI | 1270 (6.3) | 574 (5.6) | 696 (7.0) | |||
| University profile | Medical | 4518 (22.4) | 2578 (25.3) | 1940 (19.5) | 97.73 * | <0.001 |
| Non-medical | 15,621 (77.6) | 7609 (74.7) | 8012 (80.5) | |||
| HDI | Very high | 18,206 (90.4) | 9432 (92.6) | 8774 (88.2) | 146.77 * | <0.001 |
| High | 785 (3.9) | 364 (3.6) | 421 (4.2) | |||
| Medium | 1000 (5.0) | 329 (3.2) | 671 (6.7) | |||
| Low | 148 (0.7) | 62 (0.6) | 86 (0.9) | |||
| GDP per capita | High | 17,716 (87.9) | 9252 (90.8) | 8464 (85.0) | 175.27 * | <0.001 |
| Upper-middle | 1059 (5.3) | 455 (4.5) | 604 (6.1) | |||
| Lower-middle | 973 (4.9) | 348 (3.4) | 625 (6.3) | |||
| Low | 391 (1.9) | 259 (2.6) | 132 (1.3) | |||
| COVID-19 pandemic announcement | Before the pandemic | 10,187 (50.6) | --- | ---- | --- | --- |
| During the pandemic | 9952 (49.4) | --- | --- | |||
| Place of study | Europe | 17,954 (89.1) | 9372 (92.1) | 8582 (86.2) | 220.82 * | <0.001 |
| North America | 147 (0.7) | 65 (0.6) | 82 (0.8) | |||
| South America | 173 (0.9) | 65 (0.6) | 108 (1.1) | |||
| Asia | 1425 (7.1) | 474 (4.7) | 951 (9.6) | |||
| Africa | 390 (1.9) | 167 (1.6) | 223 (2.2) | |||
| Australia | 50 (0.3) | 35 (0.3) | 15 (0.2) | |||
| Alcohol | Yes | 16,517 (82.0) | 8833 (86.8) | 7684 (77.1) | 317.47 * | <0.001 |
| No | 3622 (18.0) | 1345 (13.2) | 2277 (22.9) | |||
| Cannabinoids | Yes | 2731 (13.6) | 1449 (14.2) | 1282 (12.9) | 8.01 * | 0.004 |
| No | 17,408 (86.4) | 8729 (12.9) | 8679 (87.1) | |||
| Psychostimulants | Yes | 729 (3.6) | 432 (4.2) | 297 (3.0) | 23.01 * | <0.001 |
| No | 19,410 (96.4) | 9746 (95.8) | 9664 (97.0) | |||
| Sedatives | Yes | 2522 (22.6) | 1183 (11.6) | 1339 (13.4) | 15.21 * | <0.001 |
| No | 17,617 (87.4) | 8995 (88.4) | 8622 (86.6) | |||
M—mean; SD—standard deviation; HDI—Human Development Index; GDP—Gross domestic product; * Chi2; # Cohen’s d; ^ comparison of distribution in relation to the COVID-19 pandemic. Statistically significant values are in bold with the significance level set at p < 0.05.