Predictors of In-Hospital Mortality in Thrombotic Thrombocytopenic Purpura in Children in the United States: A Population Analysis

A Systematic Review of the Epidemiology and Disease Burden of Congenital and Immune-Mediated Thrombotic Thrombocytopenic Purpura

Congenital (cTTP) and immune-mediated (iTTP) thrombotic thrombocytopenic purpura are serious and rare clotting disorders resulting from a deficiency in the ADAMTS13 enzyme. A systematic review was conducted using the Ovid® MEDLINE & Embase databases to synthesize the epidemiology and burden of cTTP and iTTP worldwide (from January 1, 2010, to February 6, 2020, with an update that covered the period January 1, 2020-February 11, 2022). Outcomes of interest were incidence and prevalence of TTP, incidence of acute episodes, mortality, burden of illness (eg complications, healthcare utilization, patient-reported outcomes) and disease management. A total of 221 eligible observational studies were included. The incidence rate of acute episodes ranged from 0.19-0.35 person-years in adult patients with cTTP, and 1.81-3.93 per million persons per year for iTTP in the general population. Triggers of acute episodes were similar for cTTP and iTTP, with pregnancy and infection the most commonly observed. Exacerbation in patients with iTTP varied widely, ranging from 2.4-63.1%. All-cause mortality was observed in 0-13.4% of patients with cTTP, across studies and follow-up periods, and in 1.1% (median follow-up: 0.4 years) to 18.8% (1 year) of patients with iTTP during acute episodes. Cardiovascular, renal, and neurological disease were common complications. TTP also led to work disturbances, feelings of anxiety and depression, and general activity impairment. TTP treatment regimens used were generally reflective of current treatment guidelines. The evidence identified describes a high patient burden, highlighting the need for effective treatment regimens leading to improvements in outcomes. Considerable evidence gaps exist, particularly for disease epidemiology, patient-reported outcomes, costs of disease management, and associated healthcare resource utilization. This review may help increase disease awareness and highlights the need for additional real-world studies, particularly in geographical regions outside the United States and Western Europe.

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.

In patients with suspected immune TTP, admission source impacts hospital length of stay and time to therapeutic plasma exchange impacts clinical outcomes

INTRODUCTION

When immune thrombotic thrombocytopenic purpura (TTP) is suspected, outcomes are impacted by time to therapeutic plasma exchange (TPE). We evaluated the impact of time to TPE on outcomes in suspected TTP cases admitted through the Emergency Department (ED) vs. transferred from another facility (Transfer).

MATERIALS AND METHODS

In a retrospective analysis of the National Inpatient Sample, we examined the association between TTP outcomes and admission source (ED vs. Transfer) for the primary outcome of time to TPE. A second stratified analyses within each analytic group examined the association of time to TPE (<1 day, 1 day, 2 days, and >2 days) and outcomes for the composite outcome of mortality, major bleeding and thrombosis.

RESULTS

Of 1195 cases, 793 (66 %) were admitted through the ED and 402 (34 %) were transferred. Compared to ED cases, Transfers had a longer hospital length of stay (14.69 vs. 16.65 days, p = 0.0060). For ED cases, TPE after >2 days was associated with higher odds of the composite outcome (OR = 1.68 95 % CI: 1.11-2.54; p = 0.0150) and mortality (OR = 3.01 95 % CI: 1.38-6.57; p = 0.0056). For Transfers, TPE on day 2 was associated with higher odds of the composite outcome (OR = 3.00 95 % CI: 1.31-6.89; p = 0.0096) and mortality (OR = 4.95 95 % CI: 1.12-21.88; p = 0.0350).

CONCLUSIONS

In suspected TTP admitted through the ED or transferred, there was no significant difference in time to TPE. A longer time to TPE was associated with worse outcomes. Future studies should evaluate strategies to decrease initial time to TPE.

Risk factors of renal trauma in children with severe Henoch-Schonlein purpura and effect of mycophenolate mofetil on pediatric renal function

BACKGROUND

Renal trauma (RT) is a common feature in children with severe Henoch-Schonlein purpura (HSP), which can elevate the chance of recurrence and trigger end-stage renal disease. The risk factors of RT in children with HSP were explored and research was conducted on relevant treatment methods.

METHODS

A total of 120 child patients with severe HSP admitted to our hospital from January 2019 to January 2020 were selected as the research cohort, and divided into a RT group (n=45) and RT-free group (n=75) according to their condition to analyze the risk factors inducing RT in pediatric patients, and mycophenolate mofetil therapy was given to both participant groups to compare their renal function indicators, immune function indicators, and adverse reaction rates (ARR) after treatment.

RESULTS

Recurrent rash, adenovirus infection, respiratory virus infection, D-dimer level, leukocyte level, urinary albumin (UA) level, and platelet level were the risk factors of RT affecting severe HSP child patients. After treatment, the renal function indicators and immune indicators of participants in both groups were significantly better than those before treatment (P<0.05), and these indicators of the RT-free group were significantly better than the RT group after treatment (P<0.05). All participants did not experience serious adverse reactions, and no significant difference was presented when comparing the ARR between the 2 groups (P>0.05).

CONCLUSIONS

Recurrent rash, adenovirus infection, respiratory virus infection, D-dimer level, leukocyte level, UA level, and platelet level are the risk factors of RT affecting children with severe HSP, and mycophenolate mofetil can improve the renal function in pediatric patients and enhance their immunity, and is thus worthy of promotion in practice.