Resource Utilization and Cost Analysis of a Chromogenic Factor X Assay for Anticoagulation Monitoring and Management

Abstract

Introduction High risk venous thrombotic states such as heparin-induced thrombocytopenia (HIT) and antiphospholipid antibody syndrome (APLS) contribute to significant patient morbidity and mortality, and financial toxicity. Traditional coagulation assays (prothrombin time [PT], activated partial thromboplastin time [aPTT], and international normalized ratio [INR]) guide anticoagulation but are unreliable in the presence of a lupus anticoagulant and/or disseminated intravascular coagulation (DIC). Further, some agents used for treatment, such as direct thrombin inhibitors (DTI), elevate the PTT, PT, and INR. Collectively, this highlights the challenge of maintaining a therapeutic index with aberrant PTT values. The chromogenic factor X (CFX) assay depends on an enzymatic reaction that generates photometrically (colorimetric) distinct signals that are proportional to factor X levels and therapeutic INR levels. Rationale for the use of CFX assay is to abrogate difficulty in guiding treatment decisions in HIT with DIC, APLS, and with DTI use. It remains unclear how the use of CFX testing and need for hematology consultation impacts clinical and financial resources at an institutional level seeking to incorporate novel coagulation tests. Here we aim to understand how involving a hematologist in decision-making when using this test can improve healthcare utilization and expenditure associated with thrombotic disease and its complications. Methods This study design was reviewed by the Institutional Review Board and met the criteria for exempt review. This is a single institution retrospective cohort analysis. All patients who had CFX assays performed between July 1, 2019 and June 30, 2021 were included. Each encounter was categorized by location (inpatient vs. outpatient), the indication prompting use of the CFX assay, and if hematology was consulted. Costs were aggregated by evaluating individual decentralized de-identified patient accounts. In particular, variable costs were evaluated to capture all costs from services rendered directly related to the anticoagulation management of the patient (i.e. cost of operations). Descriptive analysis was done for aggregated variable costs and expenditures relevant to the CFX-guided anticoagulation treatment episode. A two-sample t-test was used to identify association between numbers of tests ordered when hematology was consulted in patient care. Statistical analysis to identify differences was set at α=0.05 or less. Maximum type I error rate of p<0.05 was used. Results In total, 179 patient charts were analyzed, of which 90 patients met inclusion criteria (Table 1). The majority of patients had the CFX assay performed inpatient; 33 had the test as an outpatient. A breakdown of testing indication is presented in Table 1, with the majority of tests ordered for APLS, HIT, and recurrent thrombosis. As show in Table 2, for inpatients, fewer tests per patient were ordered when hematology is consulted compared (3.4 vs. 5.4 tests/patient, p=0.005 [α = 0.05]). The mean direct variable cost (DVC) was not statistically different, however there was a median $1800 cost savings when hematology was consulted. There is no difference in length of stay (LOS). All outpatient tests were ordered by a hematologist. In total, 40 tests were ordered for 33 patients (1.2 tests/patient) with a mean DVC of $602.75. Conclusion Our study highlights that there was a statistically significant decrease in tests ordered when a hematologist is involved. For institutions adopting novel coagulation testing, expert hematology consultation helps improve fiscal resource utilization and clinical practice. The discordance of mean and median DVC suggest that variation is not normally distributed. This is often seen in healthcare finance where macro-economic or supply-side factors dictate variation in medically ill patients. Further, the wide ranges in DVC and in LOS suggest a possibly more complex patient population for whom hematology was consulted. Therefore, we highlight that consultation with a hematologist should be considered in complex patients, particularly for anticoagulation given the significant implications inadequate treatment can have. Hematologist can help with anticoagulation management, and their involvement appears to correlate with decreased testing and improved overall savings even with the cost incurred of the consultant. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal