Nishad 2019.

Study characteristics
Methods	A 4‐armed (Gingko biloba and placebo; caroverine and placebo), parallel‐group randomised controlled trial with 3 months duration of treatment and 4 weeks, 12 weeks and 6 months duration of follow‐up
Participants	Location: India Setting: single‐centre study, Otolaryngology Department, India Sample size: Number randomised: 22 in Ginkgo biloba group and 21 in placebo group Number completed: 22 in Ginkgo biloba group and 21 in placebo group Participant baseline characteristics: Age: range 18 to 60; for all 4 arms most of the patients were in the 5th decade of life (40.69%) followed by 4th decade of life (22.09%) Gender (male/female, %): 67/33 for all 4 arms  Other characteristics: group level data for baseline tinnitus, hearing loss, depression and anxiety were not provided. All patients had cochlear synaptic tinnitus diagnosed with extensive test battery (Audiometry (0 to 16,000 Hz); impedance audiometry; Eustachian tube function test; acoustic reflex (Ipsi and Contra); clinching reflex test; reflex decay; tinnitus matching; tinnitus grading; short increment sensitivity index; brainstem evoked response audiometry). Inclusion criteria: age between 18 and 60 years, diagnosis of tinnitus, unilateral or bilateral, cochlear hearing defect, reflex audiometry confirming cochlear‐synaptic tinnitus and excluding middle ear tinnitus, written consent after explanation by consultant in charge Exclusion criteria: patients not willing to give written consent after receiving due instructions, reasonable doubts as to the patient’s co‐operation, severe secondary disorders (i.e. any acute/chronic illness), contra‐indication for caroverine therapy (e.g. severe hypertension), concomitant symptoms, pregnancy or plan for having children, hydrops cochlea or Ménière's disease, retrocochlear hearing defect, blast injury, status post psychiatrist therapy, status post operation of the middle ear, pulse‐synchronous tinnitus, excessive consumption of alcohol, drug or nicotine, known to intolerance to caroverine, concomitant medication, medicative tinnitus therapy within 1 week prior to enrolment, masticatory movements influencing subjective tinnitus sensation
Interventions	Intervention group: Ginkgo biloba (60 mg of Ginkgo biloba extract) 12‐hourly for a period of 3 months Comparator group: placebo (60 mg of placebo) 12‐hourly for a period of 3 months Use of additional interventions: none reported
Outcomes	Primary outcome: change in tinnitus grading measured with unspecified non‐standard questionnaire at 4 weeks, 12 weeks and 6 months Secondary outcome: quality of life (method not described) and tinnitus matching (method not described) at 4 weeks, 12 weeks and 6 months
Funding sources	None specified
Declarations of interest	The authors declare that they have no conflict of interest
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	By using a computer‐generated block randomisation method participants were randomised into 4 groups.
Allocation concealment (selection bias)	Unclear risk	Information not reported in the manuscript.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Information not reported in the manuscript.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Information not reported in the manuscript.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants seemed to complete the study, no dropout reported.
Selective reporting (reporting bias)	High risk	Quality of life stated as primary outcome but no results were reported. Report mentions "tinnitus matching" improved but this was not pre‐defined as an outcome measure.
Other bias	High risk	Lack of criteria for defining improvement, no statistical analyses, results do not justify conclusions. Audiological selection criteria complex and of uncertain significance in selecting stated aetiological group. No prospective protocol available. No funding sources reported.