Predictors of in-hospital mortality and acute myocardial infarction in thrombotic thrombocytopenic purpura

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.

Should we consider caplacizumab as routine treatment for acute thrombotic thrombocytopenic purpura? An expert perspective on the pros and cons

INTRODUCTION

Immune thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening disorder. Caplacizumab has been the latest drug incorporated into the initial treatment of acute episodes, allowing for faster platelet recovery and a decrease in refractoriness, exacerbation, thromboembolic events, and mortality. However, caplacizumab is also associated with a bleeding risk and higher treatment costs, which prevent many centers from using it universally.

AREAS COVERED

Studies that included iTTP and/or caplacizumab to date were selected for this review using PubMed and MEDLINE platforms. We describe outcomes in the pre-caplacizumab era and after it, highlighting the benefits and risks of its use early in frontline, and also pointing out special situations that require careful management.

EXPERT OPINION

It is clear that the availability of caplacizumab has significantly and favorably impacted the management of iTTP patients. Whether this improvement is cost-effective still remains uncertain, and data on long-term sequelae and different healthcare systems will help to clarify this point. In addition, evidence of the bleeding/thrombotic risk of iTTP patients under this drug needs to be better addressed in future studies.

Cardiovascular Disease and Stroke in Immune TTP-Challenges and Opportunities

Advances in the management of immune thrombotic thrombocytopenic purpura (iTTP) have dramatically improved outcomes of acute TTP episodes, and TTP is now treated as a chronic, relapsing disorder. It is now recognized that iTTP survivors are at high risk for vascular disease, with stroke and myocardial infarction occurring at younger ages than in the general population, and cardiovascular disease is the leading cause of premature death in this population. iTTP appears to have a phenotype of accelerated vascular aging with a particular predilection for cerebral circulation, and stroke is much more common than myocardial infarction. In addition to traditional cardiovascular risk factors, low ADAMTS13 activity during clinical remission may be a risk factor for some of these outcomes, such as stroke. Recent studies also suggest that Black patients, who are disproportionately affected by iTTP in the United States, are at higher risk of adverse cardiovascular outcomes, likely due to multifactorial reasons. Additional research is required to establish the risk factors and mechanisms underlying these complications in order to institute optimal screening strategies and identify interventions to improve outcomes.

Impact of Acute Coronary Syndrome on Clinical Outcomes in Patients With Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening clinical syndrome characterized by microangiopathy and a variable degree of end-organ ischemic damage. Cardiac involvement has been recognized as a major cause of mortality in these patients. In this study, we queried the National Inpatient Sample (NIS) for all patients hospitalized with thrombotic microangiopathy from 2002 to 2017, who also received plasma exchange (PLEX) during the same admission. A total of 6,214 patients with TTP were identified. We stratified patients based on whether or not they had acute coronary syndrome (ACS) during admission. ACS was documented in 6.3% of patients. Compared with patients without ACS, those with ACS were relatively older (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.02-1.03) and had a relatively higher prevalence of heart failure (OR, 2.02; 95% CI, 1.53-2.67) and coronary artery disease (OR, 2.69; 95% CI, 2.03-3.57). Certain complications were more prevalent in the ACS group including acute cerebrovascular accident (OR, 3.33; 95% CI, 2.94-3.78), acute heart failure (OR, 1.91; 95% CI, 1.67-2.19), acute kidney injury (OR, 1.76; 95% CI, 1.59-1.95), cardiogenic shock (OR, 2.15; 95% CI, 1.72-2.69), and respiratory failure (OR, 1.48; 95% CI, 1.32-1.66). Despite wider utilization of therapeutic plasmapheresis and improved supportive management of patients with TTP, associated morbidity and mortality remain significant. We demonstrate from this large retrospective cohort that ACS is an independent predictor of higher morbidity and mortality in TTP patients.

Prognostic value of dynamic cardiac biomarkers in patients with acquired refractory thrombocytopenic purpura: A retrospective study in Chinese population

Introduction

Thrombotic thrombocytopenic purpura (TTP) is becoming a curable disease with the introduction of therapeutic plasma exchange (TPE). However, cardiovascular complications remain essential causes of mortality in patients with refractory TTP, while the association of cardiac biomarkers with the prognosis of TTP warrants further investigation.

Methods

Patients admitted to the First Affiliated Hospital of Soochow University for refractory TTP from 2013 through 2020 were included in this retrospective study. Clinical characteristics were collected from electronic health records. Biomarker levels on admission and post TPE were recorded. Logistic regression was adopted to identify risk factors for mortality.

Results

A total of 78 patients with refractory TTP were included in this study. Twenty‐one patients died during hospitalization, with a mortality rate of 26.9%. High‐sensitivity cardiac troponin T (hs‐cTnT), N‐terminal probrain natriuretic peptide (NT‐proBNP), and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ratios (AAR) were increased in deceased patients compared with the survival group. Multivariate analysis showed that AAR after TPE was associated with overall mortality (OR: 4.45, 95% CI 1.09–18.19). The areas under the receiver operator characteristic curve (AUC) of AAR, hs‐cTnT, and NT‐proBNP for the association with mortality were 0.814, 0.840, and 0.829, respectively.

Conclusion

Higher post‐TPE cardiac biomarker levels are associated with increased in‐hospital mortality in patients with refractory TTP.

Plasma Levels of Big Endothelin-1 Are Associated with Renal Insufficiency and In-Hospital Mortality of Immune Thrombotic Thrombocytopenic Purpura

Immune thrombotic thrombocytopenic purpura (iTTP) is caused by severe deficiency of plasma ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity. Despite advances in early diagnosis and management, the mortality rate of acute iTTP remains high in a large part of world where access to some of the most novel therapies is limited. To determine the role of plasma big endothelin-1 (bigET-1) or its bioactive product ET-1 as a biomarker and/or a pathogenic factor in acute iTTP, plasma levels of bigET-1 were determined using an immunoassay in patients with iTTP on admission and during remission, as well as in healthy controls; moreover, the biological effect of ET-1 in thrombus formation was determined by a microfluidic assay. We show that plasma levels of bigET-1 were dramatically increased in patients with acute iTTP on admission, which was significantly decreased during clinical response/remission; elevated admission levels of plasma bigET-1 were associated with low estimated glomerular filtration rate, the need for intensive care unit admission or intubation, and in-hospital mortality. Moreover, an addition of a bioactive product ET-1 to cultured endothelial cells in a microfluidic channel significantly accelerated the rate of thrombus formation under arterial flow. Our results demonstrate for the first time a potential role of measuring plasma bigET-1 in patients with acute iTTP in assessing the disease severity and risk of in-hospital mortality, which may help stratify patients for a more aggressive monitoring and therapeutic strategy; also, the bioactive ET-1, derived from bigET-1, may result in acute renal injury in TTP patient, likely through its vasoconstriction and prothrombotic properties.

The standard of care for immune thrombotic thrombocytopenic purpura today

Targeted therapy of immune thrombotic thrombocytopenic purpura (iTTP) requires acurate and prompt diagnosis and differentiation from complement-mediated hemolytic uremic syndrome and other causes of thrombotic microangiopathy. ADAMTS-13 (A Disintegrin And Metalloprotease with ThromboSpondin-1 Domain, member 13) evaluation (activity and inhibitors or anti-ADAMTS-13 IgG) is the key for diagnosis and further management of patients with suspected iTTP during acute episode and in clinical response or remission. Clinical trial results and real-world data have demonstrated the efficacy and safety of the triple therapy consisting of therapeutic plasma exchange, caplacizumab, and immunosuppressives (e.g., corticosteroids and rituximab) for acute iTTP. Such a therapeutic strategy has significantly accelerated the normalization of platelet counts, decreased the length of stays in the intensive care unit and the hospital, but most importantly reduced the mortality rate. The present review highlights some of the important advancements for the diagnosis and management of iTTP and proposes triple therapy as the standard of care for acute iTTP today.

Elevated plasma levels of syndecan-1 and soluble thrombomodulin predict adverse outcomes in thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a potentially fatal blood disorder resulting from acquired deficiency of plasma ADAMTS13 activity. Despite recent advances in early diagnosis and novel therapeutics, the mortality rate of acute iTTP remains as high as 10% to 20%. Moreover, a reliable clinical and laboratory parameter that predicts disease severity and outcomes is lacking. We show in the present study that plasma levels of syndecan-1 (Sdc-1) and soluble thrombomodulin (sTM) on admission were dramatically increased in patients with acute iTTP and remained substantially elevated in a subset of patients compared with healthy controls. The elevated admission plasma levels of Sdc-1 and sTM were associated with abnormal Glasgow coma scale scores, low estimated glomerular filtration rates, the need for intensive care, and in-hospital mortality rates. Moreover, a further simultaneous increase in plasma Sdc-1 and sTM levels at the time of clinical response/remission (eg, when normalization of platelet counts and substantial reduction of serum lactate dehydrogenase activity were achieved) was highly predictive of iTTP recurrence. These results demonstrate that endothelial injury, resulting from disseminated microvascular thromboses, is severe and persistent in patients with acute iTTP. Plasma levels of Sdc-1 and sTM on admission and in remission are predictive of in-hospital mortality and recurrence of acute iTTP, respectively. Thus, an incorporation of such novel plasma biomarkers into the risk assessment in acute iTTP may help implement a more vigorous and intensive therapeutic strategy for these patients.

Cardiovascular Complications and Their Association With Mortality in Patients With Thrombotic Thrombocytopenic Purpura

BACKGROUND

Despite widespread availability of plasmapheresis, the mortality in thrombotic thrombocytopenic purpura remains high. Cardiovascular complications have been reported as an important cause of morbidity in these patients. The burden and prognostic implications of these complications have not been well studied. We analyzed the rates of cardiovascular complications in thrombotic thrombocytopenic purpura, temporal trends, and studied its impact on in-hospital mortality.

METHODS

We analyzed the National Inpatient Sample (NIS) from January 2005 to September 2015 to identify adult patients with thrombotic thrombocytopenic purpura. This group was further refined by excluding patients who did not receive therapeutic plasmapheresis, and other conditions that can mimic thrombotic thrombocytopenic purpura. We identified the age- and sex-stratified rates of cardiac arrhythmias, cardiac conduction system disorders, heart failure, acute coronary syndrome, myocarditis, pericarditis, takotsubo cardiomyopathy, cardiogenic shock, cardiac arrest, and stroke. We also compared in-hospital mortality with and without cardiovascular complications.

RESULTS

Among 15,054 thrombotic thrombocytopenic purpura hospitalizations (mean age 46.4 years, 69% in the 18- to 54-age group, 66.2% women, and 42.9% white), a cardiovascular complication was observed in 3802 (25.3%) hospitalizations. The following cardiovascular complications were identified: stroke (10.4%), heart failure (8.3%), acute coronary syndrome (6.4%), atrial tachyarrhythmia (5.9%), ventricular tachyarrhythmia (2.0%), cardiogenic shock (0.5%), takotsubo cardiomyopathy (0.1%), atrioventricular block (0.2%), myocarditis or pericarditis (0.3), and cardiac arrest (1.9%). Rates of several cardiovascular complications were significantly higher in patients 55 years or older compared to a younger age group, whereas males had higher rates of acute coronary syndrome and tachyarrhythmias compared to females. Overall, the cardiovascular complication rate was stable during the study period. The presence of a major cardiovascular complication was associated with a significantly higher in-hospital mortality (19.7%) as compared with no major cardiovascular complication (4.1%) (adjusted odds ratio 2.09, 95% confidence interval 1.41-3.09, P <0.001). Results were generally consistent in age and sex subgroups.

CONCLUSION

Cardiovascular complications were frequently observed at a rate of 1 in 4 in patients hospitalized for thrombotic thrombocytopenic purpura and were associated with substantially higher in-hospital mortality. These findings underscore the need to promptly identify and treat these complications to improve outcomes.

PROFOUND VISUAL RECOVERY AT 16 MONTHS AFTER RESOLUTION OF SEROUS RETINAL DETACHMENTS SECONDARY TO THROMBOTIC THROMBOCYTOPENIC PURPURA: CASE REPORT AND LITERATURE REVIEW

PURPOSE

To report a unique case of dramatic improvement in objective visual function during the recovery phase, after resolution of thrombotic thrombocytopenic purpura-related serous retinal detachments and to review prognostic trends in reported cases involving the macula.

METHODS

Observational case report and literature review.

RESULTS

A 36-year-old white woman with thrombotic thrombocytopenic purpura developed vision loss from serous retinal detachments in both eyes. Over a 16-month period, after both retinae remained attached, best-corrected visual acuity improved from 20/400 to 20/50 in both eyes with dramatic improvement on optical coherence tomography and autofluorescence imaging.

CONCLUSION

Although thrombotic thrombocytopenic purpura is a life-threatening illness, visual prognosis in patients with macula off serous retinal detachments appears excellent. Most cases reviewed in literature improved to baseline visual acuity, but recovery periods ranged from days to many months. Hyperautofluorescent granularity on autofluorescence photography may be an indicator of chronic retinal detachment and a more delayed visual recovery.

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

BACKGROUND

Despite proven efficacy and increased availability of therapeutic plasma exchange, thrombotic thrombocytopenic purpura (TTP) is associated with significant morbidity and mortality.

STUDY DESIGN AND METHODS

This study utilized the Kids' Inpatient Database and National Inpatient Sample (2003 to 2016) to study predictors of in-hospital mortality in hospitalized TTP patients. Adjusted odds ratios of death with various putative risk factors were calculated using multiple regression analysis.

RESULTS

Among 1568 hospitalizations with TTP as primary admission diagnosis who underwent therapeutic plasma exchange, 69 deaths were identified (all-cause mortality, 0.04%; median time-to-death, 6 wk). Overall, hospitalizations rates were fairly similar across the study period. The overall incidence of TTP related hospitalizations is 1.51 per 100,000 hospitalizations. A total of 69 deaths were reported with an all-cause in-hospital mortality rate of 0.04% (69/1568). The median time-to-death was 6 weeks. The majority of deaths occurred in age 16 to 20 years (58%), females (56.5%), and African American (42.9%) as shown in Table 2. Mean age for nonsurvivors was 14 years and the mean age of 15 years for survivors (P=0.01). Younger age, male sex, African-American ethnicity, malignancy, sepsis, acute kidney injury, platelet transfusion was significantly associated with mortality in patients with TTP.

CONCLUSIONS

Early and targeted therapy for high risk individuals should be used to guide management of TTP patients for improved survival outcomes.

Efficacy and safety of open-label caplacizumab in patients with exacerbations of acquired thrombotic thrombocytopenic purpura in the HERCULES study

BACKGROUND

Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare, life-threatening autoimmune thrombotic microangiopathy. Caplacizumab, an anti-von Willebrand Factor Nanobody® , is effective for treating aTTP episodes and is well tolerated.

OBJECTIVES AND METHODS

In the phase 3 HERCULES trial (NCT02553317), patients with aTTP received double-blind caplacizumab or placebo during daily therapeutic plasma exchange (TPE) and for ≥30 days thereafter. Patients who experienced an exacerbation while on blinded study drug treatment switched to receive open-label caplacizumab plus re-initiation of daily TPE. Exacerbations were defined as recurrence of disease occurring within 30 days after cessation of daily TPE.

RESULTS

Thirty-one patients (placebo, n = 28; caplacizumab, n = 3) had an exacerbation during double-blind treatment. Twenty-eight patients switched to open-label caplacizumab (placebo, n = 26; caplacizumab, n = 2); the three others discontinued upon exacerbation. Median time to platelet count response (≥150 × 109 /L) was 3.49 days upon receiving caplacizumab. There were no deaths. During open-label treatment, further exacerbation or a major thromboembolic event (vena cava thrombosis) was experienced by one patient (3.6%) each. Consistent with the double-blind phase, the most frequent treatment-emergent adverse events were catheter site hemorrhage (28.6%), headache (21.4%), and epistaxis (17.9%).

CONCLUSIONS

These results suggest that caplacizumab was efficacious and well tolerated in patients with aTTP who experienced a disease exacerbation during double-blind treatment in HERCULES.

Longitudinal assessments of plasma ADAMTS13 biomarkers predict recurrence of immune thrombotic thrombocytopenic purpura

Immune thrombotic thrombocytopenic purpura (iTTP) is primarily caused by immunoglobulin G (IgG)-type autoantibodies that bind and inhibit plasma ADAMTS13 activity and/or accelerate its clearance from circulation. Approximately 50% of patients with iTTP who achieve initial clinical response to therapy experience recurrence (ie, exacerbation and/or relapse); however, a reliable biomarker that predicts such an event is currently lacking. The present study determines the role of longitudinal assessments of plasma ADAMTS13 biomarkers in predicting iTTP exacerbation/recurrence. Eighty-three unique iTTP patients with 97 episodes from the University of Alabama at Birmingham Medical Center between April 2006 and June 2019 were enrolled. Plasma levels of ADAMTS13 activity, antigen, and anti-ADAMTS13 IgG on admission showed no significant value in predicting iTTP exacerbation or recurrence. However, persistently low plasma ADAMTS13 activity (<10 U/dL; hazard ratio [HR], 4.4; 95% confidence interval [CI], 1.6-12.5; P = .005) or high anti-ADAMTS13 IgG (HR, 3.1; 95% CI, 1.2-7.8; P = .016) 3 to 7 days after the initiation of therapeutic plasma exchange was associated with an increased risk for exacerbation or recurrence. Furthermore, low plasma ADAMTS13 activity (<10 IU/dL; HR, 4.8; 95% CI, 1.8-12.8; P = .002) and low ADAMTS13 antigen (<25th percentile; HR, 3.3; 95% CI, 1.3-8.2; P = .01) or high anti-ADAMTS13 IgG (>75th percentile; HR, 2.6; 95% CI, 1.0-6.5; P = .047) at clinical response or remission was also predictive of exacerbation or recurrence. Our results suggest the potential need for a more aggressive approach to achieve biochemical remission (ie, normalization of plasma ADAMTS13 activity, ADAMTS13 antigen, and anti-ADAMTS13 IgG) in patients with iTTP to prevent the disease recurrence.

Expert statement on the ICU management of patients with thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is fatal in 90% of patients if left untreated and must be diagnosed early to optimize patient outcomes. However, the very low incidence of TTP is an obstacle to the development of evidence-based clinical practice recommendations, and the very wide variability in survival rates across centers may be partly ascribable to differences in management strategies due to insufficient guidance. We therefore developed an expert statement to provide trustworthy guidance about the management of critically ill patients with TTP. As strong evidence was difficult to find in the literature, consensus building among experts could not be reported for most of the items. This expert statement is timely given the recent advances in the treatment of TTP, such as the use of rituximab and of the recently licensed drug caplacizumab, whose benefits will be maximized if the other components of the management strategy follow a standardized pattern. Finally, unanswered questions are identified as topics of future research on TTP.

Sepsis and septic shock: endothelial molecular pathogenesis associated with vascular microthrombotic disease

In addition to protective “immune response”, sepsis is characterized by destructive “endothelial response” of the host, leading to endotheliopathy and its molecular dysfunction. Complement activation generates membrane attack complex (MAC). MAC causes channel formation to the cell membrane of pathogen, leading to death of microorganisms. In the host, MAC also may induce channel formation to innocent bystander endothelial cells (ECs) and ECs cannot be protected. This provokes endotheliopathy, which activates two independent molecular pathways: inflammatory and microthrombotic. Activated inflammatory pathway promotes the release of inflammatory cytokines and triggers inflammation. Activated microthrombotic pathway mediates platelet activation and exocytosis of unusually large von Willebrand factor multimers (ULVWF) from ECs and initiates microthrombogenesis. Excessively released ULVWF become anchored to ECs as long elongated strings and recruit activated platelets to assemble platelet-ULVWF complexes and form “microthrombi”. These microthrombi strings trigger disseminated intravascular microthrombosis (DIT), which is the underlying pathology of endotheliopathy-associated vascular microthrombotic disease (EA-VMTD). Sepsis-induced endotheliopathy promotes inflammation and DIT. Inflammation produces inflammatory response and DIT orchestrates consumptive thrombocytopenia, microangiopathic hemolytic anemia, and multiorgan dysfunction syndrome (MODS). Systemic inflammatory response syndrome (SIRS) is a combined phenotype of inflammation and endotheliopathy-associated (EA)-VMTD. Successful therapeutic design for sepsis can be achieved by counteracting the pathologic microthrombogenesis.

Cardiac implications of thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a multisystem disorder that essentially can affect any organ in the human body. The hallmark of the pathogenesis in TTP is the large von Willebrand factor multimers on platelet-mediated micro-thrombi formation, leading to microvascular thrombosis. Autopsy studies showed that cardiac arrest and myocardial infarction are the most common immediate causes of death in these patients. Clinical manifestations of cardiac involvement in TTP vary dramatically, from asymptomatic elevation of cardiac biomarkers, to heart failure, MI and sudden cardiac death. There is limited knowledge about optimal cardiac evaluation and management in patients with TTP. The absence of typical cardiac symptoms, combined with complicated multi-organ involvement in TTP, may contribute to the under-utilization of cardiac evaluation and treatment. Prompt diagnosis and timely initiation of effective therapy could be critically important in selected cases. Based on our experience and this review of the literature, we developed several recommendations for focused cardiac evaluation for patients with acute TTP: (1) patients with suspected or confirmed TTP should be screened for the potential presence of cardiac involvement with detailed history and physical, electrocardiogram and cardiac enzymes; (2) clinical deterioration of TTP patients warrants immediate cardiac reevaluation; (3) TTP patients with clinical evidence of cardiac involvement should be monitored for telemetry, cardiac biomarkers and evaluated with transthoracic echocardiography. These patients require urgent targeted TTP treatment as well as cardiac-specific treatment. Aspirin therapy is indicated for all TTP patients. Since epicardial coronary artery involvement is rare, cardiac catheterization is usually not required, given the high risk for hemorrhage and kidney injury; (4) we recommend evidence-based medical therapy for ischemic symptoms and heart failure. TTP patients with evidence of cardiac involvement would also benefit from routine cardiology follow up during remission.

Genetic variants in ADAMTS13 as well as smoking are major determinants of plasma ADAMTS13 levels

The metalloprotease ADAMTS13 cleaves von Willebrand factor (VWF) in circulating blood, limiting the size of VWF multimers and regulating VWF activity. Abnormal regulation of VWF contributes to bleeding and to thrombotic disorders. ADAMTS13 levels in plasma are highly variable among healthy individuals, although the heritability and the genetic determinants of this variation are unclear. We performed genome-wide association studies of plasma ADAMTS13 concentrations in 3244 individuals from 2 independent cohorts of healthy individuals. The heritability of ADAMTS13 levels was between 59.1% (all individuals) and 83.5% (siblings only), whereas tobacco smoking was associated with a decrease in plasma ADAMTS13 levels. Meta-analysis identified common variants near the ADAMTS13 locus on chromosome 9q34.2 that were significantly associated with ADAMTS13 levels and collectively explained 20.0% of the variance. The top single nucleotide polymorphism (SNP), rs28673647, resides in an intron of ADAMTS13 (β, 6.7%; P = 1.3E-52). Conditional analysis revealed 3 additional independent signals represented by rs3739893 (β, -22.3%; P = 1.2E-30) and rs3124762 (β, 3.5%; P = 8.9E-9) close to ADAMTS13 and rs4075970 (β, 2.4%; P = 6.8E-9) on 21q22.3. Linkage analysis also identified the region around ADAMTS13 (9q34.2) as the top signal (LOD 3.5), consistent with our SNP association analyses. Two nonsynonymous ADAMTS13 variants in the top 2 independent linkage disequilibrium blocks (Q448E and A732V) were identified and characterized in vitro. This study uncovered specific common genetic polymorphisms that are key genetic determinants of the variation in plasma ADAMTS13 levels in healthy individuals.

Acute Coronary Syndromes in Patients with Hematological Disorders

Hematological conditions can lead to serious disturbances in blood rheology, being frequently associated with increased systemic inflammation and increased risk of bleeding. The imbalance between coagulation and thrombolytic factors in patients with acute coronary syndromes may lead to undesirable outcomes, and the success of emergency coronary angioplasty or by-pass grafting may be altered by increased bleeding in coagulopathies such as hemophilia. This paper intends to review the present knowledge in the field of acute coronary syndromes in subjects with hematological and onco-hematological disorders such as thrombotic thrombocytopenic purpura, immune thrombocytopenic purpura, von Willebrand disease, hemophilia, polycythemia vera, erythrocyte disorders, myelodysplastic syndrome, leukemia, lymphoma or myeloma.

Comorbidity in Adult Patients Hospitalized with Type 2 Diabetes in Northeast China: An Analysis of Hospital Discharge Data from 2002 to 2013

This study aims to evaluate the comorbidity burden and patterns among adult patients hospitalized with a diagnosis of type 2 diabetes mellitus (T2DM) in Northeast China using hospital discharge data derived from the electronic medical record database between 2002 and 2013. 12.8% of 4,400,892 inpatients aged ≥18 had a diagnosis of T2DM. Sex differences in prevalence varied among those aged <50, 50–59, and ≥60. Twenty-seven diseases were determined as major comorbidities of T2DM. Essential hypertension was the most common comorbidity of T2DM (absolute cooccurrence risk, 58.4%), while T2DM was also the most popular comorbidity of essential hypertension. Peripheral and visceral atherosclerosis showed the strongest association (relative cooccurrence risk, RCoR 4.206). For five leading comorbidities among patients aged ≥40, male patients had a stronger association with disorders of lipid metabolism than female patients (RCoR 2.779 versus 2.099), and female patients had a stronger association with chronic renal failure than male patients (RCoR 2.461 versus 2.155). Leading comorbidities, except chronic renal failure, had declining associations with T2DM with increased age. Collectively, hospital discharge data can be used to estimate disease prevalence and identify comorbidities. The findings provided comprehensive information on comorbidity patterns, helping policy makers and programs in public health domains to estimate and evaluate the epidemic of chronic diseases.

Thrombotic thrombocytopenic purpura presenting as acute coronary syndrome

In patients presenting with thrombotic thrombocytopenia purpura and non‐ST elevation myocardial infarction, prompt initiation of plasma exchange takes precedence over other invasive diagnostic procedures for coronary artery disease. Such procedures should be delayed until clinical condition and laboratory parameters have been stabilized.

Prognostic risk-stratified score for predicting mortality in hospitalized patients with thrombotic thrombocytopenic purpura: nationally representative data from 2007 to 2012

BACKGROUND

Despite proven efficacy and increased availability of therapeutic plasma exchange (TPE), mortality for patients with thrombotic thrombocytopenic purpura (TTP) remains high with a limited understanding of those at highest risk of death.

STUDY DESIGN AND METHODS

This study utilized the Nationwide Inpatient Sample (2007-2012) to derive a prognostic score for mortality in hospitalized TTP patients. Odds ratios of death with various putative risk factors adjusted for age, sex, and race were calculated (adjOR). Weighted mean of adjOR estimates were incorporated in a risk-stratified score.

RESULTS

Among 8203 hospitalizations with TTP as primary admission diagnosis who underwent TPE, 613 deaths were identified (all-cause mortality, 7.5%; median time-to-death, 9 days; interquartile range, 4-14 days). In multivariable logistic regression, arterial thrombosis (adjOR 6.7, 95% confidence interval [CI], 1.1-40.9), intracranial hemorrhage (adjOR, 6.1; 95% CI, 1.6-23.2), age at least 60 years (adjOR, 3.5; 95% CI, 2.1-5.6), renal failure (adjOR, 2.6; 95% CI, 1.5-4.5), ischemic stroke (adjOR, 2.4; 95% CI, 1.2-5.0), platelet (PLT) transfusions (adjOR, 2.2; 95% CI, 1.2-4.1), and myocardial infarction (adjOR, 2.3; 95% CI, 1.2-4.6) were significant independent predictors of mortality in TTP patients who underwent TPE. A prognostic weighted mortality prediction scoring system incorporating arterial thrombosis, intracranial hemorrhage, age, renal failure, ischemic stroke, PLT transfusion, and myocardial infarction showed very good discrimination and was predictive of 78.6% deaths.

CONCLUSIONS

Early and targeted therapy for high-risk individuals should be used to guide management of TTP patients for improved survival outcomes.

Differences in the Prevalence of Obesity, Smoking and Alcohol in the United States Nationwide Inpatient Sample and the Behavioral Risk Factor Surveillance System

BACKGROUND

The lack of adequate and standardized recording of leading risk factors for morbidity and mortality in medical records have downstream effects on research based on administrative databases. The measurement of healthcare is increasingly based on risk-adjusted outcomes derived from coded comorbidities in these databases. However inaccurate or haphazard assessment of risk factors for morbidity and mortality in medical record codes can have tremendous implications for quality improvement and healthcare reform.

OBJECTIVE

We aimed to compare the prevalence of obesity, overweight, tobacco use and alcohol abuse of a large administrative database with a direct data collection survey.

MATERIALS AND METHODS

We used the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for four leading risk factors in the United States Nationwide Inpatient Sample (NIS) to compare them with a direct survey in the Behavioral Risk Factor Surveillance System (BRFSS) in 2011. After confirming normality of the risk factors, we calculated the national and state estimates and Pearson's correlation coefficient for obesity, overweight, tobacco use and alcohol abuse between NIS and BRFSS.

RESULTS

Compared with direct participant questioning in BRFSS, NIS reported substantially lower prevalence of obesity (p<0.01), overweight (p<0.01), and alcohol abuse (p<0.01), but not tobacco use (p = 0.18). The correlation between NIS and BRFSS was 0.27 for obesity (p = 0.06), 0.09 for overweight (p = 0.55), 0.62 for tobacco use (p<0.01) and 0.40 for alcohol abuse (p<0.01).

CONCLUSIONS

The prevalence of obesity, overweight, tobacco smoking and alcohol abuse based on codes is not consistent with prevalence based on direct questioning. The accuracy of these important measures of health and morbidity in databases is critical for healthcare reform policies.

Secondary thrombotic microangiopathy in two patients with Philadelphia-positive hematological malignancies treated with imatinib mesylate

Drug-mediated thrombotic microangiopathy may cause life-threatening medical emergencies. Novel targeted therapies have dramatically changed the prognosis of a number of oncological diseases. Tyrosine kinase inhibitors of the Breakpoint Cluster Region-Abelson (BCR-ABL) oncoprotein are used in patients with chronic myeloid leukemia or Philadelphia chromosome-positive acute lymphoblastic leukemia. Imatinib mesylate, which was the first anti-BCR-ABL tyrosine kinase inhibitor, has demonstrated a high tolerance profile and efficacy in these patients for many years. Good results have also been observed in patients with gastrointestinal stromal tumors. In this study, we describe two patients with Philadelphia chromosome-positive hematological malignancies who presented with secondary thrombotic microangiopathy that was most likely linked to the use of imatinib. Other potential causes of thrombotic microangiopathy were discarded, and the predisposing role of some comorbidities and potential short or long-term drug-drug interactions was assessed. The clinical and biological data were more indicative of atypical secondary hemolytic uremic syndrome in one of the cases and of secondary thrombotic microangiopathy with renal and cardiac impairment in the other, which is also categorized as secondary hemolytic uremic syndrome. The outcome was favorable after imatinib discontinuation and the treatment of severe cardiac and renal failures.