Evaluation of undesirable outcomes
EGFR-TKI-related AEs from EGFR-TKI treatment initiation to the first documented disease progression or death were recorded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) ver. 4.0. The highest-grade AEs during each therapy were recorded. We also reviewed any unexpected inpatient hospitalizations from EGFR-TKI treatment initiation to the first documented disease progression or death. An unexpected hospitalization event was defined as one of the following: (1) exacerbation of NSCLC, which needed inpatient management despite EGFR-TKI treatment; (2) EGFR-TKI-related AEs, which needed inpatient management; and (3) complications unrelated to NSCLC or EGFR-TKI treatment, which needed inpatient management.