Olanzapine for chemotherapy-induced nausea and vomiting: systematic review and meta-analysis

BACKGROUND Chemotherapy induced nausea and vomiting (CINV) remains the most distressing event in patients receiving highly emetogenic chemotherapy (HEC) or moderately emetogenic chemotherapy (MEC). OBJECTIVE Therefore, this meta-analysis was conducted to evaluate the efficacy of olanzapine containing regimen in preventing acute, delayed and overall phases of CINV. METHODS PubMed, EBSCO, and Cochrane central register of controlled trials electronic databases were searched to identify RCTs that compared the effects of olanzapine with non-olanzapine regimen in preventing CINV. Randomized clinical trials (RCTs) that compared olanzapine containing regimen with non-olanzapine regimen were included. The primary outcomes were the percentage of patients achieving no vomiting or no nausea in acute, delayed and overall phases. RESULTS 13 RCTs that enrolled 1686 participants were included in this meta-analysis. 852 patients were assigned to olanzapine and 834 patients were assigned to non-olanzapine regimen (other standard antiemetic regimen). The percentages of no emesis achieved were 87.5%, 76.2%, 73.6% in olanzapine versus 76.7%, 61.8%, and 56.4% in non-olanzapine regimen in acute, delayed and overall phases, respectively. The percentages of no nausea were 82%, 64.3%, 61.6% in olanzapine group versus 71.3%, 41.8%, and 40.6% in non-olanzapine group in acute, delayed and overall phases, respectively. In general, olanzapine containing regimen achieved statistical superiority to non-olanzapine regimen in no vomiting endpoint in acute phase (OR 2.16; 95%CI 1.60 to 2.91, p<0.00001; I-square=5%; p=0.40), delayed phase (OR 2.28; 95%CI 1.1.46 to 3.54, p=0.0003; I-square=65%; p=0.001) and overall phase (OR 2.48; 95%CI 1.59 to 3.86, p<0.0001; I-square=69%; p< 0.0001). CONCLUSION The current meta-analysis showed that olanzapine was statistically and clinically superior to non-olanzapine regimen in preventing CINV in most domains of the parameters.