Abstract: Objective To find out about the incidence of thrombocytopenia in large samples of hospitalized patients using bevacizumab in the real world, and to identify the risk factors. Methods The electronic information of all inpatients who used bevacizumab in our hospital between 2010 and 2020 was retrospectively monitored with the help of Adverse Drug Events Active Surveillance and Assessment System-II (ADE-ASAS-II). After the positive cases were determined, the propensity score 1:1 was used to match the control group, and the related risk factors were identified using binary logistic regression. Results Among the 4 864 inpatients treated with bevacizumab, 455 developed thrombocytopenia, with an incidence of 10.00%. A platelet base value < 150 ×10⁹·L^-1（OR=11.896,95%CI：8.270~17.111）, low leukocyte base value（OR=1.801,95%CI：1.213~2.675）, low erythrocyte base value（OR=1.561,95%CI：1.085~2.246）, stage Ⅳtumor (TNM stage)（OR=1.814,95%CI：1.059~3.107）, total number of times of chemotherapy≥ 10（OR=2.537, 95%CI：1.675~3.842）, and combination with paclitaxel and platinum（OR=2.658,95%CI：1.267~5.578） were risk factors for thrombocytopenia after using bevacizumab while the combination of platinum and pemetrexed regimen （OR=0.289,95% CI：0.147~0.568）was a protective factor for thrombocytopenia. Conclusion When bevacizumab is used in clinic, close attention should be paid to inpatients with risk factors such as a low platelet base value, multiple courses of treatment, combined treatment with paclitaxel and platinum.

Key words: bevacizumab, adverse drug reaction, automatic monitoring, risk factor