Inclusion Criteria
•at least 2 claims with a diagnosis of ITP in any position (ICD-9 = 287.31) at least 5 days apart within the identification period or at least 1 claim for eltrombopag or romiplostim (the earliest date of ITP diagnosis or of eltrombopag or romiplostim receipt will be considered the diagnosis index date)
•at least one diagnostic claim with evidence of receipt of treatment for ITP including a pharmacy claim for corticosteroids, intervenous immunoglobulin (IVIG), Rho(D) immune globulin, eltrombopag, romiplostim, rituximab, or other ITP medication or a procedure code for a splenectomy
•commercial or Medicare Advantage health plan enrollees 18 years of age or older
•continuous enrollment with medical and pharmacy coverage for at least 182 days prior to the index date (baseline period) and a minimum of 90 days after the index date (follow-up period);

Exclusion Criteria
•diagnoses for hepatitis, HIV, or heparin-induced ITP at any time during the baseline or follow-up period
•evidence of use of chemotherapy at any time during the baseline or follow-up period