Table 3 Planned data for extraction

Study information

- First author

- Year of publication

- Country

- Study type

Population and setting

- Sample size, % female

- Age (mean, median or range)

COVID-19 determinants

- Time point (month/year) of data measurement

- Policy restrictions in the measurement period, described by using the Oxford COVID-19 Stringency Index and the School Closure Index [6] as a proxy indicator

Pre-pandemic baseline

- Time point (month/year) of data measurement

- Link between pre-pandemic and during pandemic population (same population, similar population, cross-sectional population sample)

Outcomes

Definition of outcome (e.g. means, SD, events)

- Diagnostic instrument

- Psychometric properties of the diagnostic instrument

- Symptom reporter (self-reported, parent-report or physician-reported)