Background  The long-term effects of participation in trials has not been reported. A randomized-controlled trial (the ONE study) reported on the management of gastro-oesophageal reflux disease with esomeprazole in primary care, testing on-demand treatment vs. treatment courses.

Aim  To evaluate the impact of participation in a trial on General Practitioners management and patient behaviour.

Methods  Management of gastro-oesophageal reflux disease was compared between General Practitioners who participated in ONE (ONE-GPs) and a random sample of General Practitioners who did not participate in ONE (Other-GPs). Symptom presentation and satisfaction with treatment was compared between patients who had participated in ONE (ONE-patients) and patients who had not (Other-patients).

Results  ONE-GPs prescribed on-demand treatment with proton-pump inhibitors to 47% of the patients, Other-GPs to 27%. ONE-patients consulted for significantly less symptoms compared with Other-patients. ONE-patients reported significantly higher patient satisfaction compared with Other-patients. ONE-patients used 98 doses during 6 months whereas Other-patients used 76 doses.

Conclusions  Participation in a clinical trial influenced both doctors and patients. Treatment modalities introduced by the trial were used in daily practice by the General Practitioners. Patients who had participated in the trial consulted for less symptoms and used more medication, compared with patients who did not participate.