What is a patient preference trial?

Researchers investigated the effectiveness of topical ibuprofen compared with oral ibuprofen for chronic knee pain in people aged over 50 years. The intervention was advice to use topical or oral ibuprofen. A randomised trial study design with parallel non-randomised preference groups was used. The study lasted for 12 months. In total, 585 participants were recruited from 26 general practices; 282 patients were allocated to the randomised groups (topical: n=138; oral: n=144) and 303 selected the preference groups (topical: n=224; oral: n=79). The study was not blinded at the general practice or participant level. The two studies (randomised and preference treatment arms) were analysed separately. All analyses were performed using an intention to treat approach, with statistical hypothesis testing based on superiority.1

The primary outcome measure was the WOMAC (Western Ontario and McMaster Universities) osteoarthritis index at 12 months. Secondary outcome measures included major and minor adverse effects. The study found no significant differences in the WOMAC index scores at 12 months between the oral and topical ibuprofen groups in either the randomised or preference arms. More minor side effects were reported with oral ibuprofen in the comparison between the randomised groups. It was concluded that advice to …