40 Is the New 50: Reducing the Need for Platelet Transfusions Prior to Lumbar Puncture in Patients with Hematologic Malignancies

Introduction: Patients with hematologic malignancies frequently require lumbar punctures (LPs) for administration of intrathecal chemotherapy. With myelosuppressive chemotherapy, thrombocytopenia is common and patients often require platelet transfusions in order to reduce the risk of bleeding during invasive procedures. However, there is a dearth of evidence supporting a platelet threshold required for LPs. Guidelines from the American Association of Blood Banks recommend a minimum platelet count of 50 x 103/µL, but this is based largely on expert opinion. Platelet transfusion is associated with risk of transfusion reaction and alloimmunization, cost, and procedural delays. Given these risks, we instituted a reduction in platelet threshold to 40 x 103/µL for lumbar puncture. We retrospectively reviewed patient outcomes to assess the safety and efficacy of this approach. Methods: In November 2017, a platelet count threshold for LPs was introduced for adult oncology patients in both the inpatient and outpatient settings at Froedtert and the Medical College of Wisconsin. Previous guidelines recommended a platelet count of 50 x 103/µL in order to undergo a lumbar puncture. This threshold was decreased to 40 x 103/µL for oncology patients. Guidelines were agreed upon and implemented in all procedure settings: the inpatient procedure team, the outpatient procedure suite, and the radiology department (for fluoroscopy-guided lumbar puncture). Data regarding the pre-procedure platelet count, number of platelet transfusions given per procedure, CSF RBCs, and occurrence of post-procedure spinal hematomas were collected through the electronic medical record. Results: From November 1, 2016 to May 1, 2018 267 oncology patients underwent a lumbar puncture. Oncologic diagnosis was NHL, ALL, AML, solid malignancy, or other hematologic malignancy/disorder in 26%, 23%, 18%, 16%, and 17%, respectively. 42% of were female. A total of 845 LPs were performed under fluoroscopy, with ultrasound guidance, and by an experienced provider in 26%, 58%, and 16% of cases respectively. 534 LPs (63%) were performed with a platelet transfusion threshold of 50 x 103/µL (Plt≥50) and 311 LPs (37%) were performed with a platelet transfusion threshold of 40 x 103/µL (Plt≥40). The average pre-LP platelet count was 152.8 x 103/µL in the Plt≥50 group and 138.4 x 103/µL in the Plt≥40 group. 79 patients in the Plt≥50 group and 42 patients in the Plt≥40 group had a recorded platelet count between 40-