老年癌症患者暴露于抗生素，但缺乏与抗生素治疗相关的不良药物事件的估计。评估抗生素治疗与老年晚期癌症患者的不良药物事件的关联。这是一项队列研究，其中暴露率是每个患者每天口服或静注抗生素治疗日的比率，结果是不良药物事件，包括心脏毒性、肝毒性、肾毒性、难辨梭状芽孢菌感染或多重耐药菌的新检测。研究对象为从三级保健中心开始接受姑息化疗的65岁及以上固体肿瘤患者（n = 914）。平均年龄为75±6.6岁，52％为女性。常见的肿瘤是肺癌（31％，n = 284）和胃肠道癌（26％，n = 234）。从姑息治疗的第一疗程到索引入院的平均时间为128天。五百三十（58％）患者在索引入院期间暴露于抗生素；其中，27％（n = 143）符合标准化感染标准。患者通常接受头孢菌素（33％，n = 298）和万古霉素（30％，n = 276）治疗。在暴露于抗生素的患者中，35％（n = 183/530）出现了不良药物事件。在多元变量测试中，抗生素治疗与不良药物事件的发生有关（>0到<1与0天治疗/患者天：调整后的对数比率[aOR] = 1.9，95％可信区间[CI]，1.2-2.8; ≥1与0日治疗/患者日：aOR = 2.1，95％ CI，1.4-3.0）。抗生素治疗与住院老年晚期癌症患者的不良药物事件独立相关。这些研究结果可能有助于姑息护理提供者的抗生素决策。

Older adults with advanced cancer are exposed to antibiotics but estimates of adverse drug events associated with antibiotic therapy are lacking.Evaluate the association of antibiotic therapy with adverse drug events in older adults with advanced cancer.Cohort study where the exposure was the ratio of days of therapy of an oral or intravenous antibiotic per patient-day and the outcome was an adverse drug event, defined as cardiotoxicity, hepatotoxicity, nephrotoxicity, Clostridioides difficile infection, or new detection of a multidrug-resistant organism.Patients aged ⩾65 years with solid tumors from a tertiary care center who received palliative chemotherapy (n = 914).Mean age was 75 ± 6.6 years, and 52% were female. Common tumors were lung (31%, n = 284) and gastrointestinal (26%, n = 234). Mean time from first course of palliative chemotherapy to index admission was 128 days. Five-hundred thirty (58%) patients were exposed to antibiotics during the index admission; of these, 27% (n = 143) met standardized criteria for infection. Patients were commonly exposed to cephalosporins (33%, n = 298) and vancomycin (30%, n = 276). Among patients exposed to antibiotics, 35% (n = 183/530) developed an adverse drug event. In multivariable testing, antibiotic therapy was associated with development of an adverse drug event (>0 to <1 vs 0 days of therapy/patient-day: adjusted odds ratio [aOR] = 1.9; 95% confidence interval [CI], 1.2-2.8; ⩾1 vs 0 days of therapy/patient-day: aOR = 2.1, 95% CI, 1.4-3.0).Antibiotic therapy was independently associated with adverse drug events in hospitalized older adults with advanced cancer. These findings may inform antibiotic decision-making among palliative care providers.