Katsu 1993.

Methods	Double‐blind, double‐dummy, head‐to‐head comparison, natural colds
Participants	167 adults, mean age, sex not reported for the subgroup of colds, 32 centres, outpatient departments of hospitals and clinics, moderate to severe URTI, not requiring antibiotics
Interventions	2 groups: loxoprofen 180 mg/day and ibuprofen 600 mg for 3 days
Outcomes	No significant difference in FGIR between 2 groups
Notes	No available data on adverse effects for the subgroup of common colds
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"... were randomly assigned to receive" Comment: insufficient information about the sequence generation process
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient information about the allocation concealment
Blinding (performance bias and detection bias) All outcomes	Low risk	"... double‐blind, double‐dummy method...active drug and placebo were quite similar in shape (in Japanese)" Comment: probably done
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	"112/130 of the CS‐600 group and 113/132 group were evaluated in the assessment improvement ratings" Comment: there are no reasons for missing participants. Insufficient reporting of attrition/exclusions to permit judgement
Selective reporting (reporting bias)	Unclear risk	No protocol, no convincing text
Other bias	Low risk	The study appears to be free of other sources of bias