Randomized Controlled Trial
The efficacy of tramadol/acetaminophen combination tablets (Ultracet®) as add-on and maintenance therapy in knee osteoarthritis pain inadequately controlled by nonsteroidal anti-inflammatory drug (NSAID).
Clin. Rheumatol. 2012 Feb 1;31(2):317-23.
Randomized Controlled Trial
Assessing chronic pain in general practice: are guidelines relevant? A cluster randomized controlled trial.
Eur J Gen Pract. 2006 Jan 1;12(2):52-7.
Randomized Controlled Trial
Educational program for physicians to reduce use of non-steroidal anti-inflammatory drugs among community-dwelling elderly persons: a randomized controlled trial.
Med Care. 2001 May 1;39(5):425-35.