A Sticky Situation: Variable Agreement Between Platelet Function Tests Used to Assess Anti-platelet Therapy Response

Background

Platelet function testing to monitor antiplatelet therapy is important for reducing thromboembolic complications, yet variability across testing methods remains challenging. Here we evaluated the agreement of four different testing platforms used to monitor antiplatelet effects of aspirin (ASA) or P2Y₁₂ inhibitors (P2Y12-I).

Methods

Blood and urine specimens from 20 patients receiving dual antiplatelet therapy were analyzed by light transmission aggregometry (LTA), whole blood aggregometry (WBA), VerifyNow PRUTest and AspirinWorks. Result interpretation based on pre-defined cutoff values was used to calculate raw agreement indices, and Pearson's correlation coefficient determined using individual units of measure.

Results

Agreement between LTA and WBA for P2Y12-I-response was 60% (r = 0.65, high-dose ADP; r = 0.75, low-dose ADP). VerifyNow agreed with LTA in 75% (r = 0.86, high-dose ADP; r = 0.75, low-dose ADP) and WBA in 55% (r = 0.57) of cases. Agreement between LTA and WBA for ASA-response was 45% (r = 0.09, high-dose collagen WBA; r = 0.19, low-dose collagen WBA). AspirinWorks agreed with LTA in 60% (r = 0.32) and WBA in 35% (r = 0.02, high-dose collagen WBA; r = 0.08, low-dose collagen WBA) of cases.

Conclusions

Overall agreement varied from 35 to 75%. LTA and VerifyNow demonstrated the highest agreement for P2Y12-I-response, followed by moderate agreement between LTA and WBA. LTA and AspirinWorks showed moderate agreement for aspirin response, while WBA showed the weakest agreement with both LTA and AspirinWorks. The results from this study support the continued use of LTA for monitoring dual antiplatelet therapy, with VerifyNow as an appropriate alternative for P2Y12-I-response. Integration of results obtained from these varied testing platforms with patient outcomes remains paramount for future studies.

Blood Product (Donor) Noninfectious and Infectious Testing and Modification

Blood transfusion begins with safe donor selection and testing. In the United States, the blood supply and transfusion are highly regulated. Blood transfusion safety is multifaceted, whereby each of the elements of the blood safety value chain, spanning donor recruitment and qualification, to collection, blood processing, testing, transfusion practice, and posttransfusion surveillance, must be optimized to minimize risk. Pathogen inactivation is a promising approach to decrease bacterial contamination of platelets, inactivate parasites and viruses, and decrease risks associated with emerging and unidentified pathogens. This article offers an overview of blood donor infectious and noninfectious testing in the United States.

COVID-19 patient plasma demonstrates resistance to tPA-induced fibrinolysis as measured by thromboelastography

Patients critically ill with COVID-19 are at risk for thrombotic events despite prophylactic anticoagulation. Impaired fibrinolysis has been proposed as an underlying mechanism. Our objective was to determine if fibrinolysis stimulated by tissue plasminogen activator (tPA) differed between COVID patients and controls. Plasma from 14 COVID patients on prophylactic heparin therapy was obtained and compared with heparinized plasma from 14 different healthy donors to act as controls. Kaolin activated thromboelastography with heparinase was utilized to obtain baseline measurements and then repeated with the addition of 4 nM tPA. Baseline fibrinogen levels were higher in COVID plasma as measured by maximum clot amplitude (43.6 ± 6.9 mm vs. 23.2 ± 5.5 mm, p < 0.0001) and Clauss assay (595 ± 135 mg/dL vs. 278 ± 44 mg/dL, p < 0.0001). With the addition of tPA, fibrinolysis at 30 min after MA (LY30%) was lower (37.9 ± 16.5% vs. 58.9 ± 18.3%, p = 0.0035) and time to 50% lysis was longer (48.8 ± 16.3 vs. 30.5 ± 15.4 min, p = 0.0053) in the COVID-19 samples. Clotting times and rate of fibrin polymerization ('R' or 'α' parameters) were largely the same in both groups. Clot from COVID patients contains a higher fibrin content compared to standard controls and shows resistance to fibrinolysis induced by tPA. These findings suggest the clinical efficacy of thrombolytics may be reduced in COVID-19 patients.

PREVALENCE OF SUB-CLINICAL MASTITIS AT BANARIPARA UPAZILLA, BARISAL

A study was aimed to determine the prevalence of sub-clinical mastitis and also determine the other risk factors that intensify this condition. Prescribed questionnaire was used to take baseline information of the animals and farms and California mastitis test kit was used to determine the SCM in lactating cow at farm level. It appears from this study that an overall prevalence of SCM was 51.56% in milking cows at Banaripara Upazilla, Barisal. Crossbred cows were significantly affected with SCM than local breed lactating cows. The farm type affect significantly (p<0.05) on the occurrence of this diseases. The prevalence of sub-clinical mastitis in cow was significantly (p<0.05) higher in 3rd (80%) parity compared to 1st (38.09%) and 2rd (45.83%) parity as well as non pregnant cows (55.55%) are more prone to infection than pregnant cow (46.43%). The farm floor condition and aged cows don’t have any effect on SCM. Prevalence of sub-clinical mastitis was significantly (p<0.05) higher in high yielding (87.5%) cows than medium (70%) to low (33.33%) yielding cows. A well documented continued research and educational effort is required to increase producer awareness of cost due to mastitis to the dairy enterprise. From this study it was concluded that cow breed, farm type, parity of cows, physiological status of animal and milk yield per cow were found to be important risk factors associated with the occurrence of sub clinical mastitis in dairy cows. The occurrence of this disease remains a substantial problem for dairy producers.

Methimazole Induced Total Myeloid Aplasia with Delayed Recovery Despite Granulocyte Colony Stimulating Factor (G-CSF): Marrow Progenitor Recovery Kinetics

An eighteen-year-old female with Graves thyrotoxicosis presented with methimazole-induced agranulocytosis and total myeloid aplasia. The bone marrow at presentation showed complete absence of myeloid precursors and striking plasmacytosis. 16 days later, myeloid precursors were still absent morphologically; however bone marrow flow cytometry and cell culture detected an improvement in myelogenesis, which was soon followed by clinical recovery of agranulocytosis. Neutrophil recovery was delayed until day 22 after cessation of methimazole despite G-CSF use, consistent with a direct toxic effect on committed myeloid cells. Our findings suggest that cell culture and flow cytometric evaluation of bone marrow myeloid progenitors can be used as a guide to anticipate neutrophil recovery.

Lupus anticoagulant acquired hypoprothrombinemia syndrome in childhood: two distinct patterns and review of the literature

INTRODUCTION

Lupus anticoagulant associated with acquired prothrombin deficiency also known as 'lupus anticoagulant hypoprothrombinemia syndrome' (LAHS) is an entity that is well described in adults and is usually associated with autoimmune conditions (LAHS-AI). However, in children, LAHS has unique features that are distinct from the adult type.

AIMS

We report two paediatric cases of LAHS, describe their distinct patterns and review the paediatric literature on LAHS.

METHODS

Case studies on two patients with LAHS were reviewed, details on their presentation, work up and management were extracted. A Medline search was conducted on LAHS in children between 1960 and 2014; Articles in languages other than English were excluded.

RESULTS

The case studies highlight the differences in the two patterns of childhood LAHS. Additionally the review of the literature reveals that there are 15 case reports and 5 case series that report 25 children with LAHS-AI, 9 case reports and 6 case series report 26 children of LAHS associated with viral infections (LAHS-VI). At presentation, all patients with LAHS-AI had positive laboratory tests for autoimmune diseases, most commonly for systemic lupus erythematosus while these tests were negative in LAHS-VI. All patients with LAHS-AI had a protracted course and needed prolonged treatment with immune-suppressive therapy while patients with LAHS-VI resolved spontaneously or needed short-term immune-modulating therapy.

CONCLUSION

In childhood, two distinct patterns of LAHS are observed, either associated with infection or autoimmune disease. Initial diagnostic investigations are critical to differentiating these two patterns as the prognosis and outcome for each is distinct.