Consecutive Inpatient Hematology Consultation Service Utilization across 11 Years in the Medical Intensive Care Unit
Authors: Allen Cecily , Streiff Michael , Naik Rakhi P P. , Knauert Melissa , Goshua George 
Published: December 2023

INTRODUCTION
The current understanding of hematology consultation service utilization is limited to four studies in the outpatient setting and zero in the inpatient setting. While training programs in non-hematology specialties (i.e., cardiology, infectious diseases, nephrology) invest in dual-trained specialty-intensivists, investments into dual-trained hematologist-intensivists are systematically underdeveloped. Despite the high clinical volume of hematology patients admitted to the Medical Intensive Care Unit (MICU), there is currently no characterization of hematology MICU service needs. We sought to begin to fill this gap by examining the volume of consecutive consultations, time to consultation, consult patient characteristics, type, and number of consult question per patient and consult categories originating in the MICU at the largest hospital in the United States (2023 Becker's Hospital Review).
METHODS
We conducted a retrospective observational study of consecutive patients 18 years of age or older who had an incident (i.e., de novo) hematology consultation while admitted to the MICU from February 2013 through March 2023 at a single academic center. Inclusion criteria included (1) age of ≥ 18, and (2) initial consultation generated during MICU admission. To ensure only incident hematology consultations originating in the MICU were examined, patients with consultation placed on the medical floor with subsequent transfer to the MICU, and re-consultations in the MICU for the same patient, were excluded. Each consult note was manually reviewed to determine the exact consultation query. Descriptive statistics collected for each patient included (1) baseline demographics, (2) labs from day of consultation, (3) time to consultation, (4) binary hospital discharge status (alive or dead), and (5) number and type of consult queries within each consult. For the latter, number of queries per each consult were also recorded (i.e., anemia and thrombocytopenia would be two independent queries), and each query was further adjudicated as pertaining to either classical or malignant hematology. Descriptive statistics were tabulated using Microsoft Excel and GraphPad 9.4.1.
RESULTS
Across 11 years of consecutive, incident consultations requested from the MICU, there were a total of 594 hematology consults with 776 total consultation queries. At time of consultation request, the median age of patients was 60 years, 47% were of female sex, and mean time to hematology consultation was 30 hours after initial MICU admission (Table 1). Of the queries, 75% pertained to classical and 25% to malignant hematology. Of the 776 consult queries, the top three overall hematology consultation queries were for thrombocytopenia (n=105), coagulopathy (n = 86), and lymphoproliferative disorders (n=77). The top three classical hematology queries were for thrombocytopenia (n=105), coagulopathy (n=86), and thrombosis (n = 76). The top three malignant hematology queries were for lymphoproliferative disorders (n=77), acute leukemia (n=48), and plasma cell dyscrasias (n=25) (Table 1).
CONCLUSIONS
To our knowledge, our study is the first to describe the volume of incident inpatient hematology consultations originating from the MICU. We found that classical hematology queries constitute three quarters of consultation volume, yet the existing literature on hematologic critical care focus only on quality improvement metrics for hematologic malignancies in the ICU. The development of quality metrics for classical hematology critical care management and identification of research are needed, particularly in the context of the identified national workforce shortage in classical hematology. Future work to examine intensivists' consultation queries originating from other intensive care units (i.e., surgical, cardiac, and neurological), would allow a data-driven evaluation of the service need for dual-trained hematologist-intensivists in the United States. The volume and complexity of classical hematology consults that arise in the ICU, as demonstrated in this study, in addition to frequent ICU consultations and admission for hematologic malignancies, highlights an area of both research and clinical practice that could support developing dual trained hematologist-intensivist to help protocolize and deliver safe and expedient care for all consult queries.