A randomized clinical trial of total parenteral nutrition in malnourished surgical patients: the rationale and impact of previous clinical trials and pilot study on protocol design.

The rationale for a large-scale clinical trial of preoperative total parenteral nutrition (TPN) is described in the context of previous clinical trials that have attempted to demonstrate reduction of operative morbidity with preoperative TPN. Defects in study design or execution potentially compromising the validity of these studies are analyzed. Results of a single-institution pilot study performed during the planning phase of the multiinstitutional preoperative TPN trial are presented. This literature review and pilot study provided the data necessary to permit appropriate design of many critical elements in the protocol for the clinical trial including sample size, eligibility criteria, duration and intensity of treatment regimens, and end-point criteria. The rationale underlying critical decisions in protocol design are presented in detail to allow more meaningful interpretation of the results of the clinical trial.