Ferraz 1991.

Methods	Randomised, double‐blind, placebo control, 2 group crossover. Duration 3 weeks (2 x 1 week crossover, 1 week washout)
Participants	Randomised n=22, Completed n=20. Mean age 62 yrs, range 47‐78 yrs. Inclusion: OA hip or knee, clinical and radiographic verification (criteria not specified)
Interventions	Tipi tea: Petiveria alliacea, aqueous extract, 3 x 200ml tea (equivalent to 9gm tipi) Placebo control: Sape, Imperata exaltata (dose not specified)
Outcomes	Pain (scale not reported) at rest, pain with mvt, pain at night, 15 metre walking time, MACTAR patient preference questionnaire
Notes	Exploratory study design; power, effect, and sample size not determined a priori. Did not report ethical oversight or compliance with guidelines. Results equivocal.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised, method not reported
Allocation concealment (selection bias)	Unclear risk	Allocation concealment not reported
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Described as double‐blind, method not reported
Incomplete outcome data (attrition bias) All outcomes	High risk	Brief report. Full report not available (high risk) Reported withdrawals (low risk)
Selective reporting (reporting bias)	Low risk	Reported adverse events (low risk)
Other bias	High risk	Criteria for diagnosis of OA not specified (high risk) Financial and in kind support not reported