NCT00743587.

Methods	Official title: a randomized, double‐blind, placebo and active controlled methodology study investigating the effects of tramadol and naproxen on the pain thresholds of patients with severe pain due to osteoarthritis of the thumb Methods not provided in detail Allocation: randomized Intervention model: cross‐over assignment Blinding: double (participant, investigator)
Participants	Diagnosed with OA of the hand, ≥ 6 months' duration and aged ≥ 18 years
Interventions	Oxycodone 20 mg Tramadol 50 mg Naproxen 500 mg Placebo
Outcomes	Major outcome Pressure pain threshold – area under the curve Minor outcomes Pressure pain threshold – at specific time points Present pain intensities – at specific time points
Notes	Study start date: September 2008 Primary completion date: March 2009 Study completion date: March 2009 Contact information: Address: Pfizer Investigational Site, Brussels, Belgium, 1070 Email: www.pfizer.com/contact/email_contact?inquiry=Clinical%20Research (to send an email) Phone: 1‐212‐733‐2323 ClinicalTrials.gov identifier: NCT00743587