Table 1.
Characteristics of the WHISTLER cohort study samples that completed the questionnaires before and throughout the COVID-19 pandemic
| Demographics | T0 (n = 224) | T1 (n = 158) | T2 (n = 149) | T3 (n = 152) | T4 (n = 128) |
|---|---|---|---|---|---|
| Age in yearsa, mean (SD) | 14.82 (1.24) | 15.53a (1.25) | 15.76 (1.28) | 16.01 (1.28) | 16.30 (1.28) |
| Gender (%) | |||||
| Girl | 118 (52.68) | 94 (59.49) | 88 (59.06) | 87 (57.23) | 82 (64.06) |
| Educational level of the adolescentb (%) | |||||
| Primary school | 3 (1.34) | 2 (1.26) | 2 (1.24) | 3 (1.97) | 2 (1.56) |
| Low | 52 (23.21) | 34 (21.52) | 27 (18.12) | 32 (21.05) | 24 (18.75) |
| Intermediate | 63 (28.13) | 39 (24.68) | 33 (22.15) | 30 (19.74) | 28 (17.72) |
| High | 101 (45.09) | 79 (50.00) | 75 (50.34) | 75 (49.34) | 64 (50.00) |
| Special education | 8 (3.57) | 4 (2.53) | 4 (2.68) | 3 (1.97) | 3 (2.34) |
| Stringency index of lockdown | NA | 78.70 | 39.81 | 62.04 | 78.80–82.41 |
NA = not applicable; SD = standard deviation; T0 = before the COVID-19 lockdown; T1 = first full lockdown (assessment April 18, 2020); T2 = first full lockdown eased (assessment July 18, 2020); T3 = partial lockdown (assessment October 18, 2020); T4 = second full lockdown (assessment February 2, 2021); WHISTLER = WHeezing Illness STudy in LEidsche Rijn.
Calculated based on completion date of follow-up questionnaire.
Low: pre–vocational secondary education; intermediate: higher general secondary education or intermediate vocational education; high: preuniversity education, higher vocational education and university.