The aim of this study was to evaluate the real-world treatment patterns, healthcare resource use and costs among patients newly diagnosed with CML who were treated with tyrosine kinase inhibitors (TKIs) in first- and second-line therapy.

The study used claims from Medicare FFS data from 1 January 2016 to 31 December 2022 (observation period). The patient identification period spanned from 1 January 2017 to 30 June 2022. The index date was the date of treatment line initiation. Patients were followed from index date until death, end of enrollment, or study end (31 December 2022), whichever came first. Each patient's follow-up was variable in length.

Variables were assessed during the follow-up period in first-line (1L) and second-line (2L) treatment cohorts and were stratified by generations of TKIs and treatment profiles. Patients were categorized into non-optimal treatment (NOPT) profiles and reference groups, and treatment patterns, healthcare resource utilization (HCRU), and payer healthcare costs were summarized descriptively for each group.

Inclusion criteria:

1. L Cohort:

   • Patients had at least one diagnosis for CML (International Classification of Diseases, 10th Revision, Clinical Modification [ICD-10-CM]: C92.1x) during the observation period.
   • Patients ≥18 years of age as of the first CML diagnosis.
   • Patients received imatinib, dasatinib, nilotinib, or bosutinib in 1L.
   • Patients initiated 1L within a maximum of 3 months following the first observed CML diagnosis.
   • Patients had at least 12 months of continuous enrollment prior to the index date.
   • Patients had at least 6 months of continuous enrollment post index date (including index date).

2. L Cohort:

   • Patients in the 1L cohort.
   • Patients received imatinib, dasatinib, nilotinib, bosutinib, ponatinib or asciminib in 2L.
   • Patients with at least 12 months of continuous enrollment prior to the index date.
   • Patients with at least 6 months of continuous enrollment post index date (including index date).

Exclusion criteria:

1. L Cohort:

   • Patients with medical services with a procedure code for imatinib any time during the observation period.
   • Patients with a diagnosis for CML remission (identified by ICD-10-CM code: C92.11) or CML relapse (ICD-10-CM code: C92.12) any time in the baseline period before the 1L initiation.
   • Patients with a medical claim associated with a clinical trial drug during the baseline period before the 1L initiation up to the end of the observation period.
   • Patients who received chemotherapy, or a TKI of interest or had a hematopoietic stem cell transplantation (HSCT) during the baseline period before 1L initiation.

2. L Cohort:

   • Patients with a diagnosis for CML remission (identified by ICD-10-CM code: C92.11) or CML relapse (ICD-10-CM code: C92.12) any time before the 2L initiation.

This was a retrospective, non-interventional cohort study.