aa Vesikari 2006b

Methods	2001 to 2002 season data from Vesikari 2006
Participants
Interventions
Outcomes
Funding Source	Industry
Notes	This second Year could be biased due to attrition
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient descriptions
Allocation concealment (selection bias)	Unclear risk	Insufficient descriptions
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Insufficient descriptions
Incomplete outcome data (attrition bias) All outcomes	High risk	The proportion of missing outcomes compared with observed event risk enough to induce clinically relevant bias in intervention effect estimate
Summary assessments	High risk	Some doubts arise from attrition bias