Objectives: The initial design of the BALANCE (Bipolar Affective disorder: Lithium / ANtiConvulsant Comparative Evaluation) Trial of maintenance treatment for bipolar disorder was based on the experience of previous trials in bipolar disorder and psychiatry and on the methods developed for large randomized trials in other areas of medicine. This report describes the adaptations to the initial design and trial procedures following the initial phases of the study. The rationale for the trial and full protocol have been published elsewhere.

Methods: A pilot study and start-up phase were used to check the tolerability of the interventions, refine the trial design and develop trial procedures that are acceptable to both clinicians and patients.

Results: Changes to the procedures included: the dropping of masking of allocated treatment from clinicians and participants; introduction of the use of postal delivery to supply medication; and dispensing with the proposed schedule of regular follow up appointments. In addition, support was made available to participating psychiatrists who often had limited experience of participating in randomized trials.

Conclusions: Pilot studies and start-up phases are essential to refine clinical trial design and allow development of procedures that are both methodologically rigorous and flexible and robust enough to promote recruitment and follow up. BALANCE is now actively recruiting in the UK and USA.