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Table 4 Results of subgroup analyses for those populations and outcomes with at least k = 4 studies in main analysis

From: Mental burden and its risk and protective factors during the early phase of the SARS-CoV-2 pandemic: systematic review and meta-analyses

Subgroup analysis (subgroups) Outcome Test for subgroup differencesa Population Subgroup difference: elevated effectb Subgroup difference: reduced effectb
Population characteristics (main studies)
Age
• 30 years
• > 30 ≤ 35 years
• > 35 ≤ 40 years
• > 40 ≤ 45 years
• multiple age groups
• age not specified
Anxiety Chi2 = 9.5, df = 5 (p = .09) GP / /
Depression Chi2 = 29.3, df = 5 (p < .001) GP ≤30 years; > 40 ≤ 45 years /
Stress Chi2 = 1043.3, df = 4 (p < .001) GP / > 40 ≤ 45 years
Anxiety Chi2 = 8.7, df = 4 (p = .07) HCW / /
Depression Chi2 = 2.2, df = 1 (p = .14) HCW / /
Sleep Chi2 = 0.3, df = 1 (p = .57) HCW / /
Anxiety Chi2 = 17.14, df = 4 (p = .002) P > 40 ≤ 45 years  
Depression Chi2 = 3.74, df = 4 (p = .44) P / /
Stressor exposure
• General population
• Students
• Others
• Special exposure
Anxiety Chi2 = 2.8, df = 3 (p = .42) GP / /
Depression Chi2 = 1.9, df = 3 (p = .60) GP / /
Stress Chi2 = 0.12, df = 3 (p = .99) GP / /
Covid-19 patient contact
• Low contact risk
• High contact risk
Anxiety Chi2 = 0, df = 1 (p = .95) HCW / /
Depression Chi2 = 1.0, df = 1 (p = .31) HCW / /
Sleep Chi2 = 0.2, df = 1 (p = .69) HCW / /
Subgroup of patients
• COVID-19 patients
• Pregnant women
• Psychiatric patients
Anxiety Chi2 = 0.3, df = 2 (p = .88) P / /
Depression Chi2 = 1.3, df = 2 (p = .51) P / /
Pandemic study characteristics
Survey startc
• ≤4 weeks
• > 4 ≤ 6 weeks
• > 6 ≤ 8 weeks
• > 8 weeks
• not specified
Anxiety Chi2 = 3.55, df = 4 (p = .47) GP / /
Depression Chi2 = 10.15, df = 4 (p = .04) GP > 8 weeks /
Stress Chi2 = 0.31, df = 4 (p = .99) GP / /
Anxiety Chi2 = 7.91, df = 4 (p = .10) HCW / /
Depression Chi2 = 0.95, df = 2 (p = .62) HCW / /
Sleep Chi2 = 4.21, df = 2 (p = .12) HCW / /
Anxiety Chi2 = 4.58, df = 2 (p = .10) P / /
Depression Chi2 = 3.08, df = 3 (p = .38) P / /
Study conduction China
• China
• Non-China
Anxiety Chi2 = 0.10, df = 1 (p = .75) GP / /
Depression Chi2 = 0.60, df = 1 (p = .44) GP / /
Stress Chi2 = 0.10, df = 1 (p = .76) GP / /
Anxiety Chi2 = 2.84, df = 1 (p = .09) HCW / /
Depression Chi2 = 0.08, df = 1 (p = .78) HCW / /
Sleep Chi2 = 0.32, df = 1 (p = .57) HCW / /
Anxiety Chi2 = 3.35, df = 1 (p = .07) P / /
Depression Chi2 = 0.62, df = 1 (p = .43) P / /
Outcome measure
• AIS
• BDI
• DASS-21
• EDPS
• EPDS-3A
• GAD-2; GAD-7
• HADS
• HAMA
• HAMD
• ISI
• PHQ-2; PHQ-9
• PSQI
• PSS
• SAS
• SDS
• SCL-90
• STAI-Y
Anxiety Chi2 = 10.7, df = 6 (p = .10) GP / /
Depression Chi2 = 11.46, df = 5 (p = .04) GP PHQ-2 /
Stress Chi2 = 0.16, df = 1 (p = .69) GP / /
Anxiety Chi2 = 2.80, df = 4 (p = .59) HCW / /
Depression Chi2 = 2.91, df = 3 (p = .41) HCW / /
Sleep Chi2 = 0.32, df = 1 (p = .57) HCW / /
Anxiety Chi2 = 1.18, df = 4 (p = .88) P / /
Depression Chi2 = 16.95, df = 5 (p = .005) P SDS; PHQ-9 /
Sample size
• < 1000
• ≥1000
Anxiety Chi2 = 1.86, df = 1 (p = .17) GP / /
Depression Chi2 = 0.03, df = 1 (p = .86) GP / /
Stress Chi2 = 2.31, df = 1 (p = .13) GP / /
Anxiety Chi2 = 2.83, df = 1 (p = .09) HCW / /
Depression Chi2 = 0, df = 1 (p = .96) HCW / /
Sleep not possible HCW / /
Anxiety Chi2 = 3.60, df = 1 (p = .06) P / /
Depression Chi2 = 0.09, df = 1 (p = .77) P / /
Comparative study characteristics
Sample size
• ≤500
• > 1000 ≤ 5000
• > 5000 ≤ 10,000
• > 10,000
Anxiety Chi2 = 0.9, df = 3 (p = .83) GP / /
Depression Chi2 = 3.5, df = 4 (p = .48) GP / /
Stress Chi2 = 8.6, df = 3 (p = .03) GP / > 5000 ≤ 10,000 participants
Anxiety Chi2 = 9.93, df = 3 (p = .02) HCW > 5000 ≤ 10,000 participants  
Depression Chi2 = 4.3, df = 2 (p = .12) HCW / /
Sleep Chi2 = 0.3, df = 1 (p = .57) HCW / /
Anxiety Chi2 = 0.1, df = 2 (p = .97) P / /
Depression Chi2 = 3.9, df = 2 (p = .14) P / /
Publication year
• ≤1 year ago
• ≤2 years ago
• > 2 ≤ 5 years ago
• > 5 ≤ 10 years ago
• > 10 years ago
Anxiety Chi2 = 8.0, df = 5 (p = .16) GP / /
Depression Chi2 = 12.4, df = 5 (p = .03) GP > 10 years ago /
Stress Chi2 = 11.6, df = 4 (p = .02) GP / ≤1 year ago
Anxiety Chi2 = 14.5, df = 3 (p = .002) HCW > 10 years ago ≤2 years ago
Depression Chi2 = 4.6, df = 1 (p = .03) HCW / ≤2 years ago
Sleep not possible HCW / /
Anxiety Chi2 = 0.1, df = 2 (p = .94) P / /
Depression Chi2 = 17.0, df = 5 (p = .005) P ≤1 year ago; > 5 ≤ 10 years ago /
Pandemic and comparative study characteristics
Relationship samples sizesd
• Ratio ≥ 2
• Ratio ≥ 0.5 < 2
• Ratio ≥ 0.1 < 0.5
• Ratio < 0.1
Anxiety Chi2 = 10.0, df = 3 (p = .02) GP Ratio ≥ 0.5 < 2 /
Depression Chi2 = 4.8, df = 3 (p = .19) GP / /
Stress Chi2 = 0.4, df = 2 (p = .84) GP / /
Anxiety Chi2 = 4.2, df = 2 (p = .12) HCW / /
Depression Chi2 = 3.8, df = 2 (p = .15) HCW / /
Sleep Chi2 = 0.32, df = 1 (p = .57) HCW / /
Anxiety Chi2 = 17.7, df = 3 (p < .001) P Ratio ≥ 0.5 < 2; Ratio < 0.1 /
Depression Chi2 = 3.0, df = 3 (p = .39) P / /
  1. Abbreviations: AIS Athens Insomnia Scale, BDI Beck Depression Inventory, DASS-21 Depression Anxiety Stress Scale-21, df degrees of freedom, EPDS Edinburgh Postnatal Depression Scale, EPDS-3A Edinburgh Postnatal Depression Scale-Anxiety subscale, GAD Generalized Anxiety Disorder Scale, GP general population, HADS Hospital Anxiety and Depression Scale, HAMA Hamilton Anxiety Rating Scale, HAMD Hamilton Depression Rating Scale, HCW healthcare workers, p p value, P patients, PHQ Patient Health Questionnaire, PSS Perceived Stress Scale, SAS Self-Rating Anxiety Scale, SCL-90 Symptom Checklist-90, SDS Zung Self-Rating Depression Scale, STAI-Y, State Trait Anxiety Inventory-Y
  2. a Chi2 = test for subgroup differences
  3. b ordered by size of effect estimate (SMD)
  4. c since first COVID-19 cases in the respective country or, in case of China, since January 20, 2020
  5. d ratio of sample size in pandemic study vs comparative study