Trial design from a clinical perspective

Abstract

This chapter is written primarily from the perspective of investigators with limited resources designing clinical trials to assess the effects of interventions on patient well-being and outcomes with the hope that the results might influence clinical practice and guidelines. Other perspectives should be taken into account. The advice may be less applicable when resources are abundant (e.g. phase III trials sponsored by a large commercial company). Much research is funded by commercial companies hoping for a return on investment; they will design clinical trials to increase the chance of a statistically positive result. Many investigators will do the same although their motivation may differ. However, practising clinicians, patients, and health services want trials that help inform their daily clinical practice rather than merely achieving statistical significance. Large studies may be statistically positive but of dubious practical significance. This chapter gives some general guidance on selecting patients, comparators, endpoints, and study design.