Increased Health Resource Utilization with the Introduction of Matrix for First-Line Treatment of Primary Central Nervous System Lymphoma
Authors: Pinto Dixon , Hillis Christopher M. 
Published: February 2021

Introduction: Prior to 2016, Primary Central Nervous System Lymphoma (PCNSL) was treated using High-Dose Methotrexate (HD-MTX) +/- Cytarabine. Since 2016, the MATRix regimen (HD-MTX, Cytarabine, Thiotepa, Rituximab) was adopted based on the IELSG32 study (Ferreri et al. Lancet 2016). Information on health resource utilization (HRU) for the MATRix regimen compared to prior standards of care is limited. We sought to investigate HRU in PCNSL patients treated with the MATRix regimen compared to other HD-MTX regimens at a single institution.
Methods: Adults (≥18years) with a diagnosis of PCNSL between January 1, 2009 and December 31, 2018 and treated with a HD-MTX regimen were included. All patients were treated in Hamilton, ON, Canada and had complete treatment data available. Patient characteristics, including age, sex, malignancy type, chemotherapy regimen, length and number of hospitalizations, and transfusion data were obtained through electronic health records. Patients treated for relapsed/refractory disease were excluded. Patients were categorized based on the treatment regimen received.
Results: Fifty-one patients [20 (39.2%) female] were included. Median age was 69.0 [range, 41 to 87]. 17 (33.3%) patients were treated with MATRix, 14 (27.5%) with HD-MTX + Cytarabine, and 18 (35.3%) with HD-MTX only. 2 (3.9%) patients were treated with other drug regimens and excluded from analysis. The mean overall length of stay (LOS) was 92.6 days [95%CI, 48.9 to 136.3] in the MATRix group, 70.5 days [95%CI, 37.4 to 103.6] in the HD-MTX + Cytarabine group, and 40.6 days [95%CI, 25.6 to 55.5] in the HD-MTX group. Mean LOS was significantly shorter in the HD-MTX group compared to MATRix group (P = 0.04), all other comparisons for LOS were not statistically significant. The mean number of red blood cell units transfused per patient was 11.5 [95%CI, 8.4 to 14.5] in the MATRix group, 10.6 [95%CI, 3.5 to 17.8] in the HD-MTX + Cytarabine group, and 1.9 [95%CI, 0.7 to 3.2] in the HD-MTX group. There were significantly more red blood cell units transfused per patient with MATRix compared to HD-MTX (RR 1.54, 95%CI, 1.05 to 2.27, P = 0.03) but not HD-MTX + Cytarabine compared to HD-MTX (RR 1.40, 95%CI, 0.92 to 2.15, P = 0.12) or HD-MTX + Cytarabine compared to MATRix (RR 1.10, 95%CI, 0.86 to 1.40, P = 0.45). The mean number of pooled platelet units transfused was 8.1 [95%CI 4.0 to 12.1] for the MATRix group, 5.3 [95%CI, 0.9 to 9.7] for the HD-MTX + Cytarabine group, and 0.7 [95%CI, 0 to 1.5] for the HD-MTX group. There were significantly more platelet blood cell units transfused per patient in the MATRix group compared to the HD-MTX group (RR 2.47, 95%CI, 1.24 to 4.92, P = 0.01), all other comparisons were not significant.
Conclusion: Our institution observed that the HRU, assessed through LOS, and number of red blood cell and platelet transfusions, in PCNSL patients was significantly higher for patients treated with a MATRix regimen in comparison to a HD-MTX only regimen but not a HD-MTX + Cytarabine regimen. These findings highlight important implications for assessing the impact to patients and systems when a new standard of care is adopted. Additionally, beyond drug acquisition costs these considerations may make the adoption of regimes such as MATRix prohibitive for resource limited settings.

Disclosures
Hillis: Roche: Honoraria.