JAK2V617F and calreticulin mutations in recurrent venous thromboembolism: results from the EDITH prospective cohort

Association of ABO blood groups with venous thrombosis recurrence in middle-aged patients: insights from a weighted Cox analysis dedicated to ambispective design

BACKGROUND

In studies of time-to-events, it is common to collect information about events that occurred before the inclusion in a prospective cohort. When the studied risk factors are independent of time, including both pre- and post-inclusion events in the analyses, generally referred to as relying on an ambispective design, increases the statistical power but may lead to a selection bias. In the field of venous thromboembolism (VT), ABO blood groups have been the subject of extensive research due to their substantial effect on VT risk. However, few studies have investigated their effect on the risk of VT recurrence. Motivated by the study of the association of genetically determined ABO blood groups with VT recurrence, we propose a methodology to include pre-inclusion events in the analysis of ambispective studies while avoiding the selection bias due to mortality.

METHODS

This work relies on two independent cohorts of VT patients, the French MARTHA study built on an ambispective design and the Dutch MEGA study built on a standard prospective design. For the analysis of the MARTHA study, a weighted Cox model was developed where weights were defined by the inverse of the survival probability at the time of data collection about the events. Thanks to the collection of information on the vital status of patients, we could estimate the survival probabilities using a delayed-entry Cox model on the death risk. Finally, results obtained in both studies were then meta-analysed.

RESULTS

In the combined sample totalling 2,752 patients including 993 recurrences, the A1 blood group has an increased risk (Hazard Ratio (HR) of 1.18, p = 4.2 × 10^-3) compared with the O1 group, homogeneously in MARTHA and in MEGA. The same trend (HR = 1.19, p = 0.06) was observed for the less frequent A2 group.

CONCLUSION

The proposed methodology increases the power of studies relying on an ambispective design which is frequent in epidemiologic studies about recurrent events. This approach allowed to clarify the association of ABO blood groups with the risk of VT recurrence. Besides, this methodology has an immediate field of application in the context of genome wide association studies.

Diagnosis and Treatment of Lower Extremity Venous Thromboembolism: A Review

IMPORTANCE

Incidence rates for lower extremity deep vein thrombosis (DVT) range from 88 to 112 per 100 000 person-years and increase with age. Rates of recurrent VTE range from 20% to 36% during the 10 years after an initial event.

OBSERVATIONS

PubMed and Cochrane databases were searched for English-language studies published from January 2015 through June 2020 for randomized clinical trials, meta-analyses, systematic reviews, and observational studies. Risk factors for venous thromboembolism (VTE), such as older age, malignancy (cumulative incidence of 7.4% after a median of 19 months), inflammatory disorders (VTE risk is 4.7% in patients with rheumatoid arthritis and 2.5% in those without), and inherited thrombophilia (factor V Leiden carriers with a 10-year cumulative incidence of 10.9%), are associated with higher risk of VTE. Patients with signs or symptoms of lower extremity DVT, such as swelling (71%) or a cramping or pulling discomfort in the thigh or calf (53%), should undergo assessment of pretest probability followed by D-dimer testing and imaging with venous ultrasonography. A normal D-dimer level (ie, D-dimer <500 ng/mL) excludes acute VTE when combined with a low pretest probability (ie, Wells DVT score ≤1). In patients with a high pretest probability, the negative predictive value of a D-dimer less than 500 ng/mL is 92%. Consequently, D-dimer cannot be used to exclude DVT without an assessment of pretest probability. Postthrombotic syndrome, defined as persistent symptoms, signs of chronic venous insufficiency, or both, occurs in 25% to 50% of patients 3 to 6 months after DVT diagnosis. Catheter-directed fibrinolysis with or without mechanical thrombectomy is appropriate in those with iliofemoral obstruction, severe symptoms, and a low risk of bleeding. The efficacy of direct oral anticoagulants-rivaroxaban, apixaban, dabigatran, and edoxaban-is noninferior to warfarin (absolute rate of recurrent VTE or VTE-related death, 2.0% vs 2.2%). Major bleeding occurs in 1.1% of patients treated with direct oral anticoagulants vs 1.8% treated with warfarin.

CONCLUSIONS AND RELEVANCE

Greater recognition of VTE risk factors and advances in anticoagulation have facilitated the clinical evaluation and treatment of patients with DVT. Direct oral anticoagulants are noninferior to warfarin with regard to efficacy and are associated with lower rates of bleeding, but costs limit use for some patients.

Low prevalence of JAK2 V617F mutation in patients with thrombosis and normal blood counts: a retrospective impact study

To determine the prevalence of the V617F Janus Kinase 2 (JAK2) mutation in patients with thrombosis without other biological signs of underlying myeloproliferative neoplasm (MPN) and identify associated risk factors for thrombosis. Over a 10-year period, data were collected from patients with thrombotic events and who had also been screened for the V617F JAK2 mutation. Patients with signs of underlying MPN, such as haematocrit levels ≥ 50% and/or platelet counts ≥ 450 × 10⁹/L and/or splanchnic thrombosis were excluded from the study. Of 340 patients fulfilling inclusion criteria, JAK2 mutation was found in 9 (2.65%), the allele burden being at least 2% in 4 (1.1%). Upon follow-up, MPN was diagnosed in the latter 4. Univariate analysis of the whole cohort showed that age (54 ± 15 vs. 64 ± 13, p = 0.027), platelet count (317 ± 111 vs. 255 ± 75, p = 0.017), C-reactive protein level > 5 mg/L (OR 7.29, p = 0.014), and splenomegaly (OR 54.5, p = 0.0002) were significantly associated with JAK2 mutation. There was also a trend for an increased risk of cerebral venous thrombosis (OR 6.54, p = 0.064). Logistic regression confirmed a significant association between splenomegaly and JAK2 mutation (OR 43.15 [95%CI, 3.05-610.95], p = 0.0054). The V617F JAK2 mutation is rarely found in patients with thrombotic events without overt MPN. Splenomegaly, however, is a statistically and clinically relevant indicator of a potential JAK2 mutation in patients with non-splanchnic thrombotic events. Such patients should require further assessment and a close follow-up.

Massive Fatal Pulmonary Embolism While on Therapeutic Heparin Drip

Venous thromboembolism (VTE) includes deep venous thrombosis (DVT) and pulmonary embolism (PE). In this article, we present a case of a patient with an acute DVT who was treated with a therapeutic heparin drip, then developed syncope while in the hospital and found to have massive bilateral PEs. This case aims to arouse the medical staff’s awareness of the VTE diagnosis even if the patient is fully anticoagulated. We review the indications for DVT hospitalization, heparin infusion monitoring, risk factors for developing PE from DVT, mechanisms of developing PE from DVT while on therapeutic anticoagulation, and signs and treatment of massive PE.

Prevalence and phenotypes of JAK2 V617F and calreticulin mutations in a Danish general population

The JAK2 V617F and calreticulin mutations (CALR) are frequent within myeloproliferative neoplasms (MPNs). JAK2 V617F has been detected in the general population, but no studies have previously investigated the CALR prevalence. Thus, we aimed to determine the CALR and JAK2 V617F population prevalence and assess the biochemical profile and lifestyle factors in mutation-positive individuals with and without MPN. 19 958 eligible participants, enrolled from 2010-2013, from the Danish General Suburban Population Study were screened for JAK2 V617F and CALR by droplet digital polymerase chain reaction with (3.2%) mutation positives of which 16 (2.5%) had MPN at baseline. Of 645 participants, 613 were JAK2 V617F positive, and 32 were CALR positive, corresponding to a population prevalence of 3.1% (confidence interval [CI], 2.8-3.3) and 0.16% (CI, 0.11-0.23), respectively. Increasing age, smoking, and alcohol were risk factors for the mutations. JAK2 V617F positives with and without MPN presented elevated odds for prevalent venous thromboembolism. The odds ratio for a diagnosis of MPN per percentage allele burden was 1.14 (95% CI, 1.09-1.18; P = 1.6 × 10−10). Mutation positives displayed higher blood cell counts than nonmutated participants, and 42% of mutation positives without MPN presented elevation of ≥1 blood cell counts; 80 (13%) even presented blood cell counts in accordance with current MPN diagnostic criteria. In conclusion, we present a novel population prevalence of CALR and a JAK2 V617F prevalence that is 3 to 30 times higher compared with less sensitive methods. Mutation-positive non-MPNs with elevated blood cell counts raise concerns of MPN underdiagnosis in the population.

Incidence of Silent Thrombosis in Patients Younger Than 60 Years With Myeloproliferative Neoplasms: Single-Center Egyptian Study

BACKGROUND

Identification of janus kinase 2 (JAK2) mutation even in absence of myeloproliferative disorders (MPNs) was found to be related to venous thromboembolism occurrence. Venous thrombosis screening is not routinely requested in patients with myeloproliferative neoplasms unless the patient is symptomatic. It has been reported that the incidence of thrombosis in elderly patients is much higher than in young patients. The aim of this work was to screen MPN patients for venous thrombosis and study its correlation with JAK2 allele burden and with MPN 10 score.

PATIENTS AND METHODS

We enrolled 73 patients with JAK2-positive MPN from our Hematology Clinic in the period August 2015 to Feb 2017. All patients had been screened for thrombosis in the venous system in lower limbs (LLs), upper limbs, portal, and mesenteric systems using color Doppler ultrasound imaging.

RESULTS

Fifty-three (72.6%) patients were younger than 60 years. Twenty-two (30%) had essential thrombocytosis, 35 (47.9%) had polycythemia rubra vera, and 16 (22%) had idiopathic myelofibrosis. Twenty-seven venous thrombotic attacks were reported in 22 (30.1%) patients. Five (6.8%) had thrombosis in 2 sites. Seventeen (23%) had superior mesenteric and portal vein thrombosis. Six (8%) had iliofemoral (8%) and 4 (5%) had combined LL and portal thrombosis. Eight (10.8%) had active thrombosis at screening. Only 3 patients (4%) were symptomatic with abdominal pain during screening. Pruritis (P = .02) and abdominal pain (P = .039) were significantly different between cases with and without thrombosis. There was no significant difference in MPN 10 score between cases with active or previous thrombosis.

CONCLUSION

We recommend routine screening for venous thrombosis in any case of MPN when diagnosed and screening for MPNs in any patient with venous thrombosis especially of the portal vein or atypical sites. If MPN patients present with increasing pruritus or abdominal pain, they also should be screened for venous thrombosis. Further research on a large scale in MPN age groups younger than 60 years regarding pathogenesis of thrombosis is highly recommended.

A hypercoagulable state leading to venous limb gangrene associated with occult lung adenocarcinoma

We report a case of lung adenocarcinoma-associated hypercoagulability leading to venous limb gangrene, managed successfully with argatroban and then dabigatran. Use of idarucizumab permitted diagnostic investigations, leading to targeted antineoplastic therapy with crizotinib, surgical resection with curative intent, and continued survival over 2 years after the index event.

[Risk factors for recurrent thrombosis in patients with polycythemia vera and essential thrombocythemia]

Objective: To analyze the clinical characteristics of recurrent thrombosis in patients with polycythemia vera (PV) and essential thrombocythemia (ET) to probe the risk factors for recurrent thrombosis in patients with ET and PV. Methods: The clinical data of 104 ET and PV patients with thrombosis in Beijing Anzhen Hospital from February 2001 to November 2016 were retrospectively analyzed. Thrombosis reoccurred in 38 patients. Statistical analyses were performed by multivariate logistic regression for risk factors of recurrent thrombosis in ET and PV patients. Results: Recurrent thrombosis occurred in 36.5% of patients with ET/PV, the total incidence rate in ET and PV patients was 9.8% patient-years, 12.3% patient-years and 5.7% patient-years in ET and PV respectively. There were a total of 56 re-thrombotic events, and 42.1% of events occurred within 1 year after the first thrombosis. The arterial re-thrombosis was 97.4% (most of acute coronary syndrome, ACS), and venous events was 2.6%. The most common cases of re-thrombosis were ACS in ET patients (18 cases, 64.3%), and cerebral infarction in PV patients (7 cases, 70.0%). The number of PV patients with 2 times or more re-thrombotic events was significantly higher than that of ET patients (9 cases, 90.0% vs 7 cases, 25.0%). The proportion of the patients with WBC>12.5×10(9)/L or Hct>45%, and thrombosis history or splenomegaly and high risk thrombotic events were higher than those with a single thrombus (52.6% vs 31.8%; 50.0% vs 30.0%; 86.8% vs 13.6%; 84.2% vs 33.3%; 52.6% vs 15.2%; 94.7% vs 53.0%; P values were 0.036,0.046, <0.001, <0.001, <0.001 and <0.001, respectively). Logistic regression analysis showed that thrombosis history (OR=13.697, P=0.025), splenomegaly (OR=13.301, P=0.034) and high risk stratification of thrombotic events (OR=44.618, P=0.025) were independent risk factors for recurrent thrombotic events. Conclusions: ET and PV patients had a higher risk of re-thrombosis. The incidence of re-thrombosis in ET was higher than in PV, ACS was more common cases of re-thrombotic events; but PV patients were more susceptible to multiple re-thromboses than ET ones, also with more cerebral infarction. Previous thrombus history, splenomegaly and high risk stratification of thrombotic events were independent risk predictors for re-thrombosis of ET and PV patients.