Subjects with a shortened activated partial thromboplastin time show increased in‐hospital mortality associated with elevated D‐dimer, C‐reactive protein and glucose levels

Effect of dual versus mono antiplatelet therapy on recurrent stroke modulated by activated partial thromboplastin time

BACKGROUND AND PURPOSE

The efficacy of dual antiplatelet treatment may be modified by many factors. The aim was to assess whether the effect of clopidogrel plus aspirin versus aspirin alone on recurrent stroke would be affected by admission activated partial thromboplastin time (aPTT).

METHODS

Data were derived from the Clopidogrel in High-Risk Patients with Acute Nondisabling Cerebrovascular Events (CHANCE) trial. A total of 5074 patients were categorized into three groups based on the aPTT distribution according to the 15th and 85th percentile. The primary outcome was any stroke within 90 days. The interaction of aPTT with antiplatelet therapy on stroke risk was assessed with a Cox proportional hazards model with adjustment for covariates.

RESULTS

In the high aPTT group (defined as ≥35.9 s), stroke occurred in 6.7% of patients in the clopidogrel-aspirin arm and 11.9% in the aspirin arm [adjusted hazard ratio (HR) 0.50; 95% confidence interval (CI) 0.29-0.85]. In the medium aPTT group (24.6-35.8 s), stroke occurred in 7.7% of patients in the clopidogrel-aspirin arm and 11.8% in the aspirin arm (adjusted HR 0.62; 95% CI 0.50-0.75). Furthermore, in the low aPTT group (≤24.5 s), stroke occurred in 11.2% of patients in the clopidogrel-aspirin arm and 9.9% in the aspirin arm (adjusted HR 1.07; 95% CI 0.65-1.62). The interaction P value of antiplatelet therapy with aPTT level at the cut-point of approximately 25 s or below was significant (P < 0.05).

CONCLUSIONS

Dual antiplatelet therapy was superior to single antiplatelet therapy in the high or medium aPTT group but not in the low aPTT group.

tPA Alu (I/D) polymorphism associates with bacterial osteomyelitis

BACKGROUND

Coagulation and fibrinolysis are important in infections and systemic inflammatory response syndrome. Polymorphisms in plasminogen activator inhibitor-1 (PAI-1, SERPINE1) and tissue plasminogen activator (tPA, PLAT), such as PAI-1 (-675 4G/5G deletion/insertion) and tPA (Alu insertion/deletion [I/D]), are associated with strokes, myocardial infarctions, bacterial infections and septic shock severity, and trauma. Osteomyelitis is a mostly posttraumatic, Staphylococcal bone infection.

PATIENTS AND METHODS

tPA Alu (I/D) (rs4646972) and PAI-1 (4G/5G) (rs1799889) polymorphisms were studied by DNA amplification with polymerase chain reaction in 261 patients with osteomyelitis and in 299 matched blood donors. Plasma PAI-1/tPA complex was assessed by enzyme-linked immuosorbent assay.

RESULTS

II homozygotes (37.9% vs 19.1%) and I allele carriers (56.3% vs 46.3%) for the tPA Alu (I/D) polymorphism were significantly more frequent in osteomyelitis patients compared to controls (P < .001). II genotype carrier osteomyelitis patients had lower PAI-1/tPA complex levels compared to those with the D allele (P ≤ .04). There was no association between these genotypes and chronicity of osteomyelitis, post-traumatic etiology, or with a specific bacterial etiology. PAI-1 (4G/4G) homozygotes were not significantly different between osteomyelitis patients and controls (P = .1).

CONCLUSIONS

We report for the first time to our knowledge an association between the tPA Alu (I/D) polymorphism and susceptibility to bacterial osteomyelitis, perhaps by fibrinolysis dysfunction.

Shortened activated partial thromboplastin time: causes and management

Throughout the long history of the hemostasis laboratory, and as an evaluation of the coagulation cascade, the results of the activated partial thromboplastin time (APTT) have primarily been considered as an index of loss-of-function and rarely as an index of gain-of-function. Nevertheless, there are now several clinical and technical reasons that no longer allow us to simply ignore or overlook shortened APTTs in laboratory practice. It has long been suspected that the leading cause of shortened APTTs are related to preanalytical problems, in which case it would be inappropriate for a laboratory to issue such a test result, which would expectedly not adequately mirror the patient's true condition. Should such artifactual results be reliably ruled out, that is by confirming short APTT values on subsequent samples, it would then be worth considering to troubleshoot potential causes, inasmuch as this phenomenon may reflect a variety of clinically meaningful conditions, including an increased risk of thromboembolic events, cancer, myocardial infarction, thyroid disorders, diabetes, and pregnancy. Although there are no univocal data supporting the origin of this singular phenomenon as yet, we strongly encourage the utility of postanalytical laboratory guidance, including a relevant short accompanying comment in the laboratory report linked to the APTT test result, for example, noting 'Short APTT-potentially reflective of in-vitro activation of blood coagulation due to difficult collection. If the value is systematically confirmed in subsequent samples, please contact the laboratory to help assess the cause'.

Alterations in some blood coagulation parameters in naturally occurring cases of canine babesiosis

Changes in coagulation parameters were studied in dogs naturally infected with Babesia canis canis (n = 30), and haemostasis was evaluated and compared to values obtained from healthy dogs (n = 29). To date, there have not been any studies examining the dynamics of thrombin-antithrombin complex formation in cases of canine babesiosis. Coagulation parameters evaluated before (day 0) and on days 1, 2, and 3 after treatment with imidocarb (6 mg/kg inj. s.c.) included the determination of platelet counts, the formation of thrombin-antithrombin complexes (TAT), prothrombin time (PT), activated partial thromboplastin time (APTT) and antithrombin III (AT III) activity. TAT complexes were significantly elevated in animals with babesiosis on days 0 and 2 (mean 49.7 and 87.7 microg/L vs. control, 7.2 microg/L). AT III activity was significantly decreased at all time-points examined. There were no differences in PT. On days 2 and 3 the APTT was significantly shortened in the infected dogs when compared to control animals (means of 21.3 and 19.2 s vs. control, 30.0 s). Our analysis demonstrated that infected dogs had significant thrombocytopenia during the course of the study (mean day 0 - 29 x 10(9) /L, day 1 - 48 x 10(9) /L, day 2 - 47 x 10(9) /L and day 3 - 87 x 10(9) /L, vs. control -259 x 10(9) /L). These data suggest that babesiosis in dogs compromise primary and secondary haemostasis and that induction of disseminated intravascular coagulation (DIC) occurs in canine babesiosis.

Detection of shortened activated partial thromboplastin times: An evaluation of different commercial reagents

INTRODUCTION

Abnormally shortened activated partial thromboplastin times (aPTT) are associated with significantly increased risk of thrombotic disorders and in-hospital mortality. Shortened aPTTs have been related to increased levels of factor (F) VIII and thrombin-antithrombin complex (TAT). In the current study, four different commercial aPTT reagents were evaluated for their performance to detect shortened aPTTs.

MATERIALS AND METHODS

aPTT of 400 patients was determined using Actin-FS (Dade Behring), APTT-SP (Instrumentation Laboratory), Automated-APTT (bioMerieux) and Platelin-LS (bioMerieux) reagents. FVIII, FIX, FXI and TAT levels were measured in shortened and normal aPTT samples.

RESULTS

An association between shortened aPTTs and elevated levels of coagulation factors (FVIII, FIX and FXI) and thrombin generation (TAT) was found with all tested aPTT reagents. Method-comparison studies demonstrated good agreement between Instrumentation Laboratory and bioMerieux reagents. However, 53 to 59% of the patients with a shortened aPTT measured with Actin-FS reagent was determined as a normal aPTT with APTT-SP, Automated-APTT and Platelin-LS reagents. These patients had increased levels of FVIII, FIX and FXI and moderately increased levels of TAT.

CONCLUSION

Overall, an acceptable agreement between the different commercial reagents was found with respect to detection of short aPTTs. However, a disparity between some of reagents existed. Actin-FS reagent appeared to be more sensitive in inducing shortened aPTT reactions than APTT-SP, Automated-APTT and Platelin-LS reagents.

Clinical laboratory findings associated with in-hospital mortality

The diagnostic approach and the clinical management of critically ill patients is challenging. The recognition of biomarkers related to in-hospital mortality is of importance for identification of patients at increased risk of death. Many prediction models assessing the severity of illness and likelihood of hospital survival were developed using logistic regression analyses. These models include several laboratory parameters, such as white blood cell counts, serum bilirubin, serum albumin, blood glucose, serum electrolytes and markers which reflect acid-base disturbances. Recently, several other biomarkers, including troponin, B-type natriuretic peptide (BNP), N-terminal proBNP, C-reactive protein, procalcitonin, cholesterol and coagulation related markers have emerged as clinically useful tools for risk stratification and mortality prediction of heterogeneous and more specific subgroups of critically ill patients. More investigations are required to verify whether risk stratification based on mortality-related biomarkers may translate into targeted treatment strategies to improve clinical outcome of the critical illness. Biomarkers which are related to in-hospital mortality are highlighted in the current review.