Adverse event severity in relation to imatinib dose and duration of imatinib treatment. Grade 2, 3, and 5 adverse events occurred more frequently on imatinib 400 mg than 200 mg daily. No grade 4 adverse events occurred. Only those adverse events possibly, probably, or definitely attributed to imatinib are shown. Gray represents 200 mg imatinib daily; and black, 400 mg imatinib daily.