Background: BTC is associated with poor prognosis and limited treatment choices. There is limited evidence on HCRU and costs among BTC patients receiving systemic treatments (ST). This study examined HCRU and total direct cost of care among BTC patients treated with ST to understand the disease burden in management of BTC. Methods: A retrospective cohort study of BTC patients who received first line (1L) ST was conducted, using US private payer Cancer Care Quality Program data and administrative claims from the HealthCore Integrated Research Database between 07/01/2014 - 03/31/2021. Patients with ampullary cancer, brain/ CNS metastases, other primary cancer before BTC diagnosis were excluded. Per patient per month (PPPM) costs in 2020 USD were calculated during 1L, 2L, and 3L treatments associated with HCRU from inpatient, emergency room, and outpatient visits as well as outpatient pharmacy dispensing. Results: Among 298 BTC patients (biliary tract, n=203; gallbladder, n=65; bile duct, n=30; stage IV, n=231; stage III, n=28; stage I/II, n=39) who received ST, mean (SD) age was 61.7 (9) years at 1L treatment initiation, and the majority were female (58%). Following 1L treatment, 44% received 2L treatment, and 16% received 3L treatment. Median follow-up was 7.6 months. Among 201 (67%) patients who had hospitalization in the follow-up period, mean (SD) number of hospitalizations was 2.5 (2), and the average length of stay was 7.0 (5) days. Total PPPM all-cause costs were the lowest during 1L treatment (mean [SD]: $19,589 [$22,603]), and increased as the treatment advanced (2L: $22,617[$19,302]; 3L: $33,534[$40,588]). Similar trend was observed in BTC-related total costs with $16,237 ($22,452) in 1L, $19,083 ($18,670) in 2L and $27,609 ($39,949) in 3L. The table summarizes BTC-related HCRU and PPPM cost during each line of therapy. Conclusions: Study findings suggest significant resource use burden and high total direct medical costs for BTC patients receiving ST. Hospitalizations and outpatient visits represent important HCRU and cost for BTC. These data indicate a need for future newer innovative therapies in the management of BTC.

Abbreviations: INP= Inpatient hospitalization; ER = Emergency room.