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Table 3 Overall scientific quality of the randomized controlled studies

From: Effect of gargling with tea and ingredients of tea on the prevention of influenza infection: a meta-analysis

Study Yamada et al. 2007 Toyoizumi et al. 2013 Ide et al. 2014
Criterion [19] [21] [22]
Cochrane Collaboration's tool for assessing risk for bias
Random sequence generation Low Low Low
Allocation concealment Low High High
Blind participants and personnel Low High High
Blind outcome assessment Low Low Low
Incomplete outcome data Low Low Low
Selective reporting Low High High
Other bias Low Unclear Unclear
Jadad score
Randomization (range, 0–2) 2 2 2
Double blinding (range, 0–2) 2 0 0
Withdrawals and dropouts (range, 0–1) 1 1 1
Total score 5 3 3