Oben 2009.

Methods	Randomised, double blind, placebo control, 4 parallel groups (2 x normal weight patients, 2 x overweight patients). Duration 8 weeks
Participants	Randomised n=80, Completed n=45. Age range 25‐60 yrs (mean age not reported). Gender data not reported. OA knee (ACR criteria) in adults of normal weight and overweight
Interventions	NP 06‐1: mixture of Phellodendron amurense tree bark extract with 50% berberine and Citrus sinensis peel extract a minimum of 30% polymethoxylated flavones, 1480mg (2 x 2 x 370mg), capsules Placebo control: ingredients not reported, capsules
Outcomes	Lequesne index, BMI, CRP, ESR
Notes	Exploratory study design; power, effect, and sample size not determined a priori. Reported university oversight, but unclear whether a formally consistuted human research ethics committee approved the research design. Results favour intervention. In the overweight intervention group, weight loss during the intervention period may have contributed to improvement.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random number sequence
Allocation concealment (selection bias)	Unclear risk	Allocation concealment not reported
Blinding (performance bias and detection bias) All outcomes	Low risk	Active intervention and placebo not distinguished by look, taste, smell, packaging, or medication regimen
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Reported withdrawals (low risk) Per protocol analysis only (unclear risk)
Selective reporting (reporting bias)	Unclear risk	Incompletely reported adverse events
Other bias	Unclear risk	Diagnosis / assessment consistent with ACR criteria (low risk) Possible confounder: the berberine component of the intervention may have contributed to weight loss