PURPOSE: High-dose methotrexate (HD-MTX) is commonly used for the treatment of osteosarcoma or for CNS involvement in lymphoproliferative neoplasms. It is often given in the inpatient setting because of monitoring requirements after administration. We conducted a process improvement initiative to change our institutional discharge criteria for HD-MTX from 0.05 µmol/L to ≤ 0.1 µmol/L to reduce cost and length of stay (LOS) for this patient population. METHODS: After an assessment of drivers of LOS among patients receiving HD-MTX, we identified discharge criteria as an actionable factor. We developed a workflow to discharge patients with 3 days of oral leucovorin and sodium bicarbonate when the methotrexate level reached ≤ 0.1 µmol/L. Patient demographics, chemotherapy regimen, cycle, dose, and LOS data were collected for a 7-month period before and a 4-month period after the intervention. Cost savings were estimated on the basis of the daily cost of a hospital bed at the institution. RESULTS: Mean LOS for the pre-intervention and postintervention group was 4.84 days (n = 49) and 3.67 days (n = 42), respectively, resulting in a 24.4% reduction in LOS, with a mean ratio of 0.756 (95% CI, 0.615 to 0.927; P = .007). Reduced LOS resulted in a decrease in cost of $1,828.73 per admission, with a 4-month savings of $76, 806.56 and projected annualized savings of $230,419.67. No patient experienced complications because of the change in discharge criteria. CONCLUSION: Liberalizing discharge criteria for HD-MTX was feasible and safe and reduced cost. Additional efforts to reduce LOS for elective chemotherapy admissions or to safely transition some of these complex regimens to the home setting are currently underway at our institution.

IntroductionMethotrexate (MTX) a folate antagonist is often given in high doses (≥500 mg/m2) to treat a variety of disease processes. While inpatient administration has been the norm, outpatient administration, has been shown to be safe, effective, and patient centered. Here in we describe development of an outpatient HDMTX protocol and our initial experience.MethodsAll patients were to receive their first cycle of HDMTX in the hospital to ensure they tolerate it well and also to use this time to assist in training for home administration. The outpatient protocol involved continuous IV sodium bicarbonate, along with oral leucovorin and acetazolamide. Patients were required to visit the infusion center daily for labs and methotrexate levels. Clear criteria for admission were developed in the case of delayed clearance or methotrexate toxicity.ResultsTwo patients completed the safety run-in phase. Both patients tolerated treatment well. There were no associated toxicity. Methotrexate cleared within 3 days for all cycles. Both patients were able to follow the preadmission instructions for sodium bicarbonate and acetazolamide. The patients reported adequate teaching on the protocol and were able to maintain frequency of urine dipstick checks.ConclusionWe developed and implemented an outpatient protocol for high dose methotrexate. This study largely details the development of this protocol and its initial safety evaluation. More work needs to be done to assess its feasibility on a larger number of patients who receive more cycles in the outpatient setting.

30 Background: High-dose methotrexate (HDMTX) is administered for the treatment of primary central nervous system (CNS) lymphoma (PCNSL), leptomeningeal metastases, and osteosarcoma, as well as CNS prophylaxis in patients with high-risk lymphoma and leukemia. Treatment is typically administered in an inpatient setting to enable aggressive hydration, urinary alkalinization, and frequent lab monitoring given the risk of acute kidney injury. Multiple pediatric centers have published experiences with outpatient administration of HDMTX. We aim to determine the toxicity rate in adult patients at SKCC receiving HDMTX to identify a population in which to pilot an outpatient HDMTX program. Methods: We performed a retrospective review of all patients receiving inpatient HDMTX at SKCC between January 1, 2018 and October 31, 2019. Results: Seventy-three patients (52% male) with median age of 60 years (range 22-81) received 255 cycles total of HDMTX. Diagnoses include PCNSL/vitreoretinal lymphoma (n=22), diffuse large B-cell lymphoma (n=17), B-cell acute lymphoblastic leukemia (n=16) and other diagnoses (n= 18). Thirty-one cycles were administered as CNS prophylaxis and 224 cycles as treatment, with a median prophylactic dose of 3.5 g/m2 (range 1-3.5) and median treatment dose of 3.5 g/m2 (range 0.25-12). The most common toxicity was acute kidney injury at a median day 3 of the cycle (range 1-7). See the table for details. Conclusions: Acute kidney injury occurred more often in the treatment group compared to prophylaxis group. Of all patients with AKI in the treatment group, 45% had a diagnosis of PCNSL. In the prophylactic group, only 21% of patients (3/14) experienced AKI of which all resolved. Of all AKI events, 90% were Grade 2 and 90% resolved. Based on these results, we plan to pilot an outpatient HDMTX program in patients receiving prophylactic HDMTX to determine its effect on patient quality of life and cost of care. [Table: see text]

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