Efficacy of therapeutic suggestions presented during anaesthesia: re-analysis of conflicting results

Abstract

Re-analysis has been made of two clinical studies which used similar methodologies but found different effects of so-called therapeutic suggestions presented to anaesthetized patients undergoing abdominal hysterectomy. The re-analysis suggested that when data from the two studies were examined jointly, it was uncertain if positive suggestions had a reliable influence upon the recovery measure of "days to discharge". The supposed positive effect reported in one of the studies may arise from a rather different distribution of data in the control group. It is proposed that the effect may be attributable to chance bias in allocation of patients to the control group, or to some other chance anomaly in the composition of the group as a result of relatively small sample size. The importance of sample size is discussed in relation to detection of effects when only a few patients may be in a state susceptible to intra-anaesthetic suggestions. The importance of presenting data distributions in addition to summary statistics is also emphasized.