Didier 2007.

Methods	Randomised DBPC trial Multicentre
Participants	Adults (age range 18 to 45 years) Active 155 (ITT 136) Active discontinued 22 Placebo 156 (ITT 148) Placebo discontinued 10
Interventions	Sublingual tablets mixed grass (orchard, meadow, perennial rye, sweet vernal, timothy grass) 4 months pre‐seasonal and co‐seasonal treatment Mean dosage 25 mcg/ml of the group 5 major allergens
Outcomes	Symptom score Quality of life Grass pollen specific IgE
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	Computer‐generated randomisation list utilised
Allocation concealment?	Low risk	Central allocation
Blinding? All outcomes	Low risk	Both investigators and participants were blinded to allocation. To maintain the blinding, patients took 2 tablets per day during the first 5 days of titration and 1 tablet per day from day 6 until the end of treatment.
Incomplete outcome data addressed? All outcomes	Low risk	Outcome data were completed for each main outcome. Attrition and exclusions were reported. The numbers in each intervention group and reasons for attrition/exclusions were reported.
Free of selective reporting?	Low risk	The specified outcomes in the methodology were reported in the results section
Free of other bias?	Low risk	No other sources of bias were detected or suspected