This Phase 4, prospective, multi-center, open-label study will evaluate safety, platelet count, and subject reported medication satisfaction in adult subjects with chronic ITP after switching to avatrombopag from eltrombopag or romiplostim. At least 100 subjects will be enrolled, 50 (±10) who have received eltrombopag and 50 (±10) who have received romiplostim for at least 90 days prior to study entry.