Fig. 1.

Study attrition. EHR electronic health record, HER2+ human epidermal growth factor receptor–positive, iKM iKnowMed, mBC metastatic breast cancer, T-DM1 ado-trastuzumab emtansine. ^aThe use of T-DM1 along with other structured data variables (e.g., stage IV disease, tumor nodal metastasis  status, record of metastases location) was first used as a screening step to identify patients presumed to have mBC based on these indicators. Metastatic status was later validated with chart review using pathology reports, progress notes, and scan reports. ^bUtilizing the full EHR capabilities refers to all of a patient’s records being available in iKM. Not all sites use iKM. Patients were included in the study if the researchers had full access to the patient records.