Sabbah 1998.

Methods	Parallel‐group RCT
Participants	113 participants with seasonal allergic conjunctivitis/rhinoconjunctivitis
Interventions	Three treatment arms: azelastine; levocabastine; placebo. Duration of treatment 14 days
Outcomes	Participants' (using diaries) and physicians' assessments (sum scores) based on a decrease of the average score > 3 units for three main eye symptoms (ocular itching, tearing, and redness) Time points: at baseline and day 3 and 14 of treatment
Country	France
Number randomised, gender (male:female)	113 participants randomised, 107 participants analysed. M:F 75:38
Age mean (SD), median, range	Mean (SD): azelastine 8.3 years (2.4); levocabastine 8.2 years (2.5); placebo 8.3 years (2.3)
Notes	Not reported when study was conducted. Source of funding Laboratoires ASTA Medica. Declaration of interest by the authors was not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The method used to generate the allocation sequence was not described
Allocation concealment (selection bias)	Unclear risk	The method used to conceal the allocation sequence was not described
Incomplete outcome data (attrition bias) All outcomes	Low risk	10% attrition, with similar numbers lost to follow‐up between arms
Selective reporting (reporting bias)	Low risk	Primary outcome result was reported according to protocol
Other bias	Low risk	No evidence of other risk of bias
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	The study did not describe details on masking of participants on the intervention allocations. Masking was not done with levocabastine due to labelling, but double‐masked with other interventions
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	The study did not describe details on masking of personnel/investigators on the intervention allocations. Masking was not done with levocabastine due to labelling, but double‐masked with other interventions