Comparison of olanzapine 2.5mg and 5mg in the prevention of chemotherapy-induced nausea and vomiting: a Japanese nationwide database study.

Abstract

Olanzapine is prescribed as prophylaxis for chemotherapy-induced nausea and vomiting at a dose of 2.5 or 5mg in Asian countries. We compared the effectiveness of olanzapine 2.5mg and 5mg in preventing chemotherapy-induced nausea and vomiting among patients receiving high-emetogenic chemotherapy for lung cancer. Using a Japanese national inpatient database, we identified patients who received olanzapine doses of 2.5 or 5mg during high-emetogenic chemotherapy for lung cancer between January 2016 and March 2021. We conducted a 1:1 propensity score-matched analysis with adjustment for various factors, including those affecting olanzapine metabolism. The outcomes were additional antiemetic drug administration (within 2-5days after chemotherapy initiation), length of hospital stay, and total hospitalization costs. Olanzapine 2.5 and 5.0mg were used in 2905 and 4287 patients, respectively. The propensity score-matched analysis showed that olanzapine 2.5mg administration was significantly associated with a higher proportion of additional antiemetic drug administration (36% vs. 31%, p < 0.001) than olanzapine 5mg. The median length of hospital stay was 8days in both groups. Total hospitalization cost did not differ significantly between the two doses of olanzapine (5061 vs. 5160 USD, p = 0.07). The instrumental variable analysis demonstrated compatible results. Prophylactic use of olanzapine 2.5mg during chemotherapy for lung cancer was associated with a higher rate of additional antiemetic drugs than olanzapine 5mg.