Prognostic value of urinary 11-dehydro-thromboxane B2 for mortality: A cohort study of stable coronary artery disease patients treated with aspirin

Adjustment for Renal Function Improves the Prognostic Performance of Urinary Thromboxane Metabolites

BACKGROUND

Systemic thromboxane A2 generation, assessed by quantifying the concentration of stable thromboxane B2 metabolites (TXB2-M) in the urine adjusted for urinary creatinine, is strongly associated with mortality risk. We sought to define optimal TXB2-M cutpoints for aspirin users and nonusers and determine if adjusting TXB2-M for estimated glomerular filtration rate (eGFR) in addition to urinary creatinine improved mortality risk assessment.

METHODS

Urinary TXB2-M were measured by competitive ELISA in 1363 aspirin users and 1681 nonusers participating in the Framingham Heart Study. Cutpoints were determined for TXB2-M and TXB2-M/eGFR using log-rank statistics and used to assess mortality risk by Cox proportional hazard modeling and restricted mean survival time. Multivariable models were compared using the Akaike Information Criterion (AIC). A cohort of 105 aspirin users with heart failure was used for external validation.

RESULTS

Optimized cutpoints of TXB2-M were 1291 and 5609 pg/mg creatinine and of TXB2-M/eGFR were 16.6 and 62.1 filtered prostanoid units (defined as pg·min/creatinine·mL·1.73 m2), for aspirin users and nonusers, respectively. TXB2-M/eGFR cutpoints provided more robust all-cause mortality risk discrimination than TXB2-M cutpoints, with a larger unadjusted hazard ratio (2.88 vs 2.16, AIC P < 0.0001) and greater differences in restricted mean survival time between exposure groups (1.46 vs 1.10 years), findings that were confirmed in the external validation cohort of aspirin users. TXB2-M/eGFR cutpoints also provided better cardiovascular/stroke mortality risk discrimination than TXB2-M cutpoints (unadjusted hazard ratio 3.31 vs 2.13, AIC P < 0.0001).

CONCLUSION

Adjustment for eGFR strengthens the association of urinary TXB2-M with long-term mortality risk irrespective of aspirin use.

Hemostatic and Thrombotic Considerations in the Diagnosis and Management of Childhood Arterial Ischemic Stroke: A Narrative Review

Although rare in children, arterial ischemic stroke (AIS) is associated with increased mortality and neurological morbidity. The incidence of AIS after the neonatal period is approximately 1-2/100,000/year, with an estimated mortality of 3-7%. A significant proportion of children surviving AIS experience life-long neurological deficits including hemiparesis, epilepsy, and cognitive delays. The low incidence of childhood AIS coupled with atypical clinical-presentation and lack of awareness contribute to delay in diagnosis and consequently, the early initiation of treatment. While randomized-clinical trials have demonstrated the efficacy and safety of reperfusion therapies including thrombolysis and endovascular thrombectomy in appropriately-selected adult patients, similar data for children are unavailable. Consequently, clinical decisions surrounding reperfusion therapy in childhood AIS are either extrapolated from adult data or based on local experience. The etiology of childhood AIS is multifactorial, often occurring in the setting of both acquired and congenital risk-factors including thrombophilia. While multiple studies have investigated the association of thrombophilia with incident childhood AIS, its impact on stroke recurrence and therefore duration and intensity of antithrombotic therapy is less clear. Despite these limitations, a significant progress has been made over the last decade in the management of childhood AIS. This progress can be attributed to international consortiums, and in selected cohorts to federally-funded clinical trials. In this narrative review, the authors have systematically appraised the literature and summarize the hemostatic and thrombotic considerations in the diagnosis and management of childhood AIS focusing on the evidence supporting reperfusion therapies, relevance of thrombophilia testing, and duration and drug choices for secondary-prophylaxis.

Non-platelet thromboxane generation is associated with impaired cardiovascular performance and mortality in heart failure

BACKGROUND

Non-platelet thromboxane generation, stimulated largely by oxidative stress, is a novel mortality risk factor in individuals with coronary artery disease. Though inversely associated with left ventricular ejection fraction (LVEF), a potential role in the pathobiology of heart failure (HF) remains poorly defined.

METHODS

Non-platelet thromboxane generation and oxidative stress were assessed by measuring urine thromboxane B₂ metabolites (TXB₂-M) and 8-isoPGF_2α by ELISA in 105 subjects taking aspirin undergoing right heart catheterization for evaluation of HF, valve disease or after transplantation. Multivariable logistic regression and survival analyses were used to define associations of TXB₂-M to invasive measures of cardiovascular performance and 4-year clinical outcome.

RESULTS

TXB₂-M was elevated (>1500 pg/mg creatinine) in 46% of subjects and correlated with HF severity by NYHA functional class and brain natriuretic peptide level, modestly with LVEF, but not with HF etiology. There was no association of oxidative stress to HF type or etiology but a trend with NYHA functional class. Multiple invasive hemodynamic parameters independently associated with TXB₂-M after adjustment for oxidative stress, age, sex and race with pulmonary effective arterial elastance (E_{a (pulmonary)})_, reflective of right ventricular afterload, being the most robust on hierarchical analysis. Similar to E_{a (pulmonary),} elevated urinary TXB₂-M associated with increased risk of death (adjusted HR 2.15, P=0.037) and combination of death, transplant, or mechanical support initiation (adjusted HR 2.0, P=0.042).

CONCLUSIONS

Non-platelet TXA₂ thromboxane generation independently associated with HF severity reflected by invasive measures of cardiovascular performance, particularly right ventricular afterload, and independently predicted long-term mortal.

Statistical analysis plan for "A randomised, controlled study to evaluate the effects of switching from cigarette smoking to using a tobacco heating product on health effect indicators in healthy subjects"

Tobacco harm reduction strategies aim to substitute smoking with potentially reduced risk products (PRRPs) such as e-cigarettes and tobacco-heating products (THPs). The health benefits of switching from smoking to PRRPs is unknown. A randomised controlled trial is being conducted to increase understanding of the health effects of switching from smoking to a THP in a 12-month long ambulatory study (ISRCTN81075760). Here we describe the study endpoints and the statistical analysis plan. Endpoints are divided into biomarkers of exposure (BoE) to tobacco smoke constituents and health effect indicators related to risk of lung cancer, cardiovascular and obstructive lung disease. These have been selected on the basis of extensive literature evidence. Three primary endpoints, augmentation index (risk factor for cardiovascular disease), total NNAL (linked to lung cancer) and 8-Epi-PGF2α type III (indicator of oxidative stress linked to various diseases), and multiple secondary endpoints will be analysed at 90, 180, and 360 days. Changes from baseline will be compared between study arms by specific contrasts in mixed models. Study wise multiple comparisons adjustments will be performed to account for multiplicity of timepoints and comparisons within timepoints. Generalisability of outcomes will be tested by a sensitivity analysis adjusting for age and gender. Importantly, an ancillary analysis will be performed to assess product compliance during the study based on plasma levels of CEVal, a surrogate marker for acrylonitrile exposure. The rationale underlying the selection of BoEs and health effect indicators, coupled with the statistical analysis plan will be central to understanding the potential health effects of replacing smoking with THP use for one year.

Influence of smoking and smoking cessation on levels of urinary 11-dehydro thromboxane B2

Background

Thromboxane is a key clinical risk endpoint of smoking-induced inflammation which has been associated in the pathogenesis of cardiovascular disease. The goal of this review is to quantify the effect of smoking and smoking cessation on one of its urinary metabolites, 11-dehydrothromboxane_B2.

Methods

PubMed and SCOPUS were searched to identify publications which report urinary 11-dehydrothromboxane_B2 levels in smokers and non-smokers, as well as articles reporting the effect of smoking cessation on urinary 11-dehydrothromboxane_B2 excretion.

Results

We found ten studies assessing urinary 11-dehydrothroboxane_B2 levels in smokers and non-smokers. Four papers reported the amount of urinary 11-dehydrothromboxane_B2 excreted in 24 h while six reported the amount excreted adjusted for creatinine. The meta-analyses comparing the excretion of urinary 11-dehydrothromboxane in current smokers to non-smokers report increased levels in current smokers (mean difference = 0.31 μg/24-h [95%CI: 0.27-0.34] and 166.45 pg/mg creatinine [95%CI: 120.51-212.40]). There were not enough publications to perform meta-analyses on the effects of smoking cessation on urinary 11-dehydrothromboxane_B2 excretion.

Conclusions

Urinary 11-dehydrothromboxane_B2 levels are increased in cigarette smokers, however, more data are needed to elucidate the effects of smoking cessation on urinary 11-dehydrothromboxane_B2 excretion.