Study designs of evaluations included in the review
The inclusion criteria for study designs were not clearly specified. Double-blind randomised controlled trials (RCTs) and observational studies were included.
Specific interventions included in the review
Studies of the herbal remedy Devil's Claw were eligible for inclusion. Included studies evaluated both the drug and extract at varying dosages; details of the dosage, harpagoside concentration and drug-to-extract ratio were reported. Treatment duration ranged from 3 weeks to 6 months. Comparator studies compared Devil's Claw with phenylbutazone, diacerhein or placebo.
Participants included in the review
Studies of participants with OA were eligible for inclusion. The authors stated that formal diagnostic criteria to confirm OA were not applied in all studies and some studies included patients with conditions other than OA.
Outcomes assessed in the review
The inclusion criteria for outcomes were not clearly specified. The outcome measures reported were pain severity (determined by either the Likert or visual analogue scales or the Hamberg Pain Adjective), concomitant medication use and change in symptoms (measured by disease-specific tools). Adverse events were also reported.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.