Results
The 176 patients included in the study received 2,320 infusions. Fifty-eight patients (33.0%) experienced IRRs, and IRRs occurred in 80 (3.4%) of the 2,320 infusions. Owing to the hierarchical structure of the data, the independence of the observed values was evaluated using the intraclass correlation coefficient. Multivariate multilevel logistic regression analysis showed that premedication with dexamethasone was effective in lowering IRR risk with trastuzumab (mg; per unit; odds ratio, OR=0.62; 95% confidence interval, 95% CI, 0.44‒0.86;p =0.005). Preoperative status (OR=34.7; 95% CI, 5.0–242.0;p <0.001) and high doses of trastuzumab (mg/kg; per unit; OR=59.6; 95% CI, 19.7–180.0; p <0.001) were independent risk factors for IRRs.