Study designs, duration, and choice of comparators including the use of placebo

This paper discusses some methodological issues that are relevant to the design of controlled trials of new medicinal products for use in the treatment of schizophrenia. Two issues are covered more generally and at greater length. The first is the use of placebo. Recent debate of this topic was stímulated by changes to the Declaratíon of Helsinki, The second is the design of studies to evaluate maíntenance treatment in the preventíon of relapse and recurrence. With respect to both of these issues, specifíc implications for trials in schizophrenia are considered. Addítional design topics addressed briefly are noninferiority designs, add-on designs, withdrawal designs, run-in periods on placebo, loss to follow-up, and short-term and long-term trials.