A machine learning approach to predict mortality due to immune-mediated thrombotic thrombocytopenic purpura.

Background: Mortality due to immune-mediated thrombotic thrombocytopenic purpura (iTTP) remains significant. Predicting mortality risk may potentially help individualize treatment. The French Thrombotic Microangiopathy (TMA) Reference Score has not been externally validated in the United States. Recent advances in machine learning technology can help analyze large numbers of variables with complex interactions for the development of prediction models. Objectives: To validate the French TMA Reference Score in the United States Thrombotic Microangiopathy (USTMA) iTTP database and subsequently develop a novel mortality prediction tool, the USTMA TTP Mortality Index. Methods: We analyzed variables available at the time of initial presentation, including demographics, symptoms, and laboratory findings. We developed our model using gradient boosting machine, a machine learning ensemble method based on classification trees, implemented in the R package gbm. Results: In our cohort (n = 419), the French score predicted mortality with an area under the receiver operating characteristic curve of 0.63 (95% CI: 0.50-0.77), sensitivity of 0.35, and specificity of 0.84. Our gradient boosting machine model selected 8 variables to predict acute mortality with a cross-validated area under the receiver operating characteristic curve of 0.77 (95% CI: 0.71-0.82). The 2 cutoffs corresponded to sensitivities of 0.64 and 0.50 and specificities of 0.76 and 0.87, respectively. Conclusion: The USTMA Mortality Index was acceptable for predicting mortality due to acute iTTP in the USTMA registry, but not sensitive enough to rule out death. Identifying patients at high risk of iTTP-related mortality may help individualize care and ultimately improve iTTP survival outcomes. Further studies are needed to provide external validation. Our model is one of many recent examples where machine learning models may show promise in clinical prediction tools in healthcare.

Race, rituximab, and relapse in TTP.

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is characterized by recurring episodes of thrombotic microangiopathy, causing ischemic organ impairment. Black patients are overrepresented in iTTP cohorts in the United States, but racial disparities in iTTP outcome and response to therapy have not been studied. Using the United States Thrombotic Microangiopathies Consortium iTTP Registry, we evaluated the impact of race on mortality and relapse-free survival (RFS) in confirmed iTTP in the United States from 1995 to 2020. We separately examined the impact of rituximab therapy and presentation with newly diagnosed (de novo) or relapsed iTTP on RFS by race. A total of 645 participants with 1308 iTTP episodes were available for analysis. Acute iTTP mortality did not differ by race. When all episodes of iTTP were included, Black race was associated with shorter RFS (hazard ratio [HR], 1.60; 95% CI, 1.16-2.21); the addition of rituximab to corticosteroids improved RFS in White (HR, 0.37; 95% CI, 0.18-0.73) but not Black patients (HR, 0.96; 95% CI, 0.71-1.31). In de novo iTTP, rituximab delayed relapse, but Black patients had shorter RFS than White patients, regardless of treatment. In relapsed iTTP, rituximab significantly improved RFS in White but not Black patients. Race affects overall relapse risk and response to rituximab in iTTP. Black patients may require closer monitoring, earlier retreatment, and alternative immunosuppression after rituximab treatment. How race, racism, and social determinants of health contribute to the disparity in relapse risk in iTTP deserves further study.

Implementation of Individualized Pain Care Plans Decreases Length of Stay and Hospital Admission Rates for High Utilizing Adults with Sickle Cell Disease.

OBJECTIVE: Patients with sickle cell disease (SCD) face inconsistent effective analgesic management, leading to high inpatient healthcare utilization and significant financial burden for healthcare institutions. Current evidence does not provide guidance for inpatient management of acute pain in adults with sickle cell disease. We conducted a retrospective analysis of a longitudinal cohort quality improvement project to characterize the role of individualized care plans on improving patient care and reducing financial burden in high healthcare-utilizing patients with SCD-related pain. METHODS: Individualized care plans were developed for patients with hospital admissions resulting from pain associated with sickle cell disease. A 2-year prospective longitudinal cohort quality improvement project was performed and retrospectively analyzed. Primary outcome measure was duration of hospitalization. Secondary outcome measures included: pain intensity; 7, 30, and 90-day readmission rates; cost per day; total admissions; total cost per year; analgesic regimen at index admission; and discharge disposition. RESULTS: Duration of hospitalization, the primary outcome, significantly decreased by 1.23 days with no worsening of pain intensity scores. Seven-day readmission decreased by 34%. Use of intravenous hydromorphone significantly decreased by 25%. The potential cost saving was $1,398,827 as a result of this quality initiative. CONCLUSIONS: Implementation of individualized care plans reduced both admission rate and financial burden of high utilizing patients. Importantly, pain outcomes were not diminished. Results suggest that individualized care plans are a promising strategy for managing acute pain crisis in adult sickle cell patients from both care-focused and utilization outcomes.

Effects of Shear Stress on Production of FVIII and vWF in a Cell-Based Therapeutic for Hemophilia A.

Microfluidic technology enables recapitulation of organ-level physiology to answer pertinent questions regarding biological systems that otherwise would remain unanswered. We have previously reported on the development of a novel product consisting of human placental cells (PLC) engineered to overexpress a therapeutic factor VIII (FVIII) transgene, mcoET3 (PLC-mcoET3), to treat Hemophilia A (HA). Here, microfluidic devices were manufactured to model the physiological shear stress in liver sinusoids, where infused PLC-mcoET3 are thought to lodge after administration, to help us predict the therapeutic outcome of this novel biological strategy. In addition to the therapeutic transgene, PLC-mcoET3 also constitutively produce endogenous FVIII and von Willebrand factor (vWF), which plays a critical role in FVIII function, immunogenicity, stability, and clearance. While vWF is known to respond to flow by changing conformation, whether and how shear stress affects the production and secretion of vWF and FVIII has not been explored. We demonstrated that exposure of PLC-mcoET3 to physiological levels of shear stress present within the liver sinusoids significantly reduced mRNA levels and secreted FVIII and vWF when compared to static conditions. In contrast, mRNA for the vector-encoded mcoET3 was unaltered by flow. To determine the mechanism responsible for the observed decrease in FVIII and vWF mRNA, PCR arrays were performed to evaluate expression of genes involved in shear mechanosensing pathways. We found that flow conditions led to a significant increase in KLF2, which induces miRNAs that negatively regulate expression of FVIII and vWF, providing a mechanistic explanation for the reduced expression of these proteins in PLC under conditions of flow. In conclusion, microfluidic technology allowed us to unmask novel pathways by which endogenous FVIII and vWF are affected by shear stress, while demonstrating that expression of the therapeutic mcoET3 gene will be maintained in the gene-modified PLCs upon transplantation, irrespective of whether they engraft within sites that expose them to conditions of shear stress.

Acute Thrombotic Microangiopathy and Cortical Necrosis Following Administration of Alemtuzumab: A Case Report.

Alemtuzumab, a humanized monoclonal antibody that targets CD52 antigens on lymphocytes and monocytes, has shown efficacy in preventing relapse in relapsing-remitting multiple sclerosis. Despite known severe (yet rare) renal side effects such as anti-glomerular basement membrane disease and membranous glomerulopathy, to our knowledge, alemtuzumab has never been documented to cause drug-induced thrombotic microangiopathy. We describe a 39-year-old woman with relapsing-remitting multiple sclerosis who developed acute kidney injury requiring renal replacement therapy after 1 dose of alemtuzumab, as well as microangiopathic hemolytic anemia and thrombocytopenia. Pathologic examination of a kidney biopsy specimen demonstrated extensive cortical necrosis and arteriolar fibrin thrombi with nonspecific immunofluorescence staining of immunoglobulin M and C3 and absence of immune deposits on electron microscopy. These findings were consistent with the diagnosis of acute thrombotic microangiopathy. She received dexamethasone and underwent plasmapheresis, which was unsuccessful at removing alemtuzumab. The patient received renal replacement therapy for approximately 7 weeks, followed by slow recovery of kidney function that returned close to her baseline.