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

Olanzapine is prescribed as prophylaxis for chemotherapy-induced nausea and vomiting at a dose of 2.5 or 5 mg in Asian countries. We compared the effectiveness of olanzapine 2.5 mg and 5 mg 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 5 mg 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 2–5 days after chemotherapy initiation), length of hospital stay, and total hospitalization costs.

Olanzapine 2.5 and 5.0 mg were used in 2905 and 4287 patients, respectively. The propensity score-matched analysis showed that olanzapine 2.5 mg administration was significantly associated with a higher proportion of additional antiemetic drug administration (36% vs. 31%, p < 0.001) than olanzapine 5 mg. The median length of hospital stay was 8 days 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 2.5 mg during chemotherapy for lung cancer was associated with a higher rate of additional antiemetic drugs than olanzapine 5 mg.