Please select the eligibility criteria that correspond to the clinical trial below.
Title: Comparing the Efficacy of Two Frequently Used Doses of Enoxaparin for VTE Prophylaxis After Bariatric Surgery
Brief Summary: Approximately two thirds of the adult population in developed countries is categorized as over-weight or obese (BMI\>30). In spite of worldwide increasing awareness, obesity is a major health concern. In the presence of numerous diets, medical therapies, and robust research, bariatric surgery remains the most effective means of weight reduction in morbidly obese patients (BMI\>40, or BMI\>35 with co-morbidities). However, bariatric surgery harbors a relatively high risk for postoperative complications; of them, venous thromboembolic events (VTE) are not common, but potentially lethal. Taken together with the propensity of morbidly obese patients to develop VTE, perioperative thromboprophylaxis is mandatory.

To date, low molecular weight heparins (LMWH) are most commonly used for VTE prophylaxis in the aforementioned population. Due to the pharmacologic properties of LMWH and the characteristics of surgically treated obese patients, the optimal dose that is to be utilized for VTE prophylaxis in this population remains unclear. Assessment of anti-FXa levels in the patients' plasma can be used in order to monitor LMWH activity. Levels of 0.2-0.5 U/ml have been proposed by some authors for VTE prophylaxis.

Few studies have compared different dosing regimens of enoxaparin (between 30mg-60mg q/12h) for VTE prophylaxis in the population undergoing bariatric surgery; nevertheless, these were small non- randomized trials, containing numerous methodological weaknesses. Hence, the optimal regimen of enoxaparin to be used for the prevention of VTE in the discussed population remains unclear.

The aim of the present study is to evaluate plasma levels of anti-FXa activity, comparing two most commonly used enoxaparin prophylactic regimens (40mg vs 60mg q/24h) in a large and homogenous cohort of sleeve gastrectomy patients. Although universally used by bariatric surgeons, the pharmacologic efficacy of these regimens has not been evaluated in patients undergoing bariatric surgery.


Options:
A: Inclusion Criteria:

* Adult patient undergoing laparoscopic sleeve gastrectomy.
* The patient undergoes the surgery in the surgical wing of the Tel-Aviv Sourasky Medical Center.
* The patient has received full information regarding the studies nature, has agreed to participate and has given informed consent (documented by a signed informed consent form).

Exclusion Criteria:

* Patients with a previous Venous Thromboembolic Event.
* Patients requiring an IVC filter.
* Patients with known thrombophilia due to coagulation factor disorders (i.e factor V leiden).
* Patients with a bleeding disorder
* Patients with renal failure.
B: Inclusion Criteria:

* Diagnosis of COVID-19 and hospitalization on ICU, or
* Diagnosis of COVID-19 and hospitalization on normal ward, or
* Diagnosis of COVID-19 (within 10 days) and troponin ≥ ULN and/or D-dimer ≥0.5 mg/L

Exclusion Criteria:

* Age below 18
* Life expectancy less than 3 months before COVID-19
* Resuscitation \> 30 minutes
* Hypersensitivity to the active substance, to Edoxaban or any of its excipients
* Significantly increased bleeding risk
* Other indication for anticoagulation beyond COVID-19
* GFR \< 15 ml/min
* Planned transfer of the patient to another clinic within the next 42 days
C: Inclusion Criteria:

1. Adults ≥ 18 years old;
2. Evaluated in the emergency unit with probable or confirmed infection by COVID-19;
3. Time between symptoms and inclusion ≤ 07 days \*;
4. Present mild or moderate signs and symptoms, with no clear indication for hospitalization;
5. Present at least 2 risk factors for complication:

   * 65 years
   * Hypertension
   * Diabetes mellitus
   * Asthma
   * Chronic Obstructive Pulmonary Disease (COPD) or other chronic lung diseases
   * Smoking
   * Immunosuppression
   * Obesity (BMI\> 30)
   * History of non-active cancer
   * Bed restriction or reduced mobility (≥50% of the wake time without walking)
   * Previous history of VTE
   * Use of oral hormonal contraceptives

Exclusion Criteria:

1. Patients \<18 years old;
2. Hospitalization indication upon first medical care;
3. Positive test for influenza in the first visit;
4. Any known liver disease associated with coagulopathy; INR (International Normalized Ratio) \> 1.5;
5. Pregnant, lactating or with the possibility of becoming pregnant and without using an adequate contraceptive method;
6. High risk of bleeding; History of bronchiectasis or pulmonary cavitation, Significant bleeding in the last 3 months, Active gastroduodenal ulcer, history of recent bleeding (within 3 months) or a high risk of bleeding;
7. Stroke within 1 month or any history of hemorrhagic or lacunar stroke or any intracranial bleeding or any intracranial neoplasia, brain metastasis, arteriovenous malformation or brain aneurysm;
8. Severe heart failure with left ventricular ejection fraction \<30% (echocardiogram or other validated method previously documented) or symptoms of heart failure class III or IV of the New York Heart Association (NYHA);
9. Estimated glomerular filtration rate (eGFR) \<30 mL / min;
10. Clinical indication for dual antiplatelet therapy or anticoagulation therapy (VTE, atrial fibrillation / flutter, mechanical valve prosthesis);
11. Marked thrombocytopenia (platelets \<50,000 / mm3);
12. Non-cardiovascular disease that is associated with a poor prognosis, for example, active cancer (excluding non-melanoma skin cancer) defined as cancer without remission or requiring active chemotherapy or adjuvant therapies such as immunotherapy or radiation therapy or that increases the risk of an adverse reaction to the evaluated interventions;
13. History of hypersensitivity or known contraindication to rivaroxaban;
14. Systemic treatment with strong inhibitors of Cytochrome P450 3A4 (CYP3A4) and glycoprotein p (Pgp) (for example, systemic azole antimycotics, such as ketoconazole and human immunodeficiency virus \[HIV\] protein inhibitors, such as ritonavir) or strong inducers of CYP 3A4, that is, rifampicin, rifabutin, phenobarbital, phenytoin and carbamazepine;
15. Current treatment being tested;
16. Concomitant participation in another study with experimental drugs in the context of COVID;
17. Use of chloroquine or hydroxychloroquine associated with azithromycin;
18. Active cancer;
19. Other contraindications to rivaroxaban;
D: Inclusion Criteria:

1. Patients aged 50 years or older with a positive test for SARS-CoV2 in the past 5 days and eligible for ambulatory treatment.
2. Presence of respiratory symptoms (i.e. cough, sore throat, or shortness of breath) or body temperature \>37.5° C.
3. Ability of the patient to travel to the study center by private transportation, performed either by accompanying person from same household or by the patient him/herself
4. Ability to comply with standard hygiene requirements at the time of in-hospital visit, including a face mask and hand disinfectant.
5. Ability to walk from car to study center or reach it using a wheel chair transport with the help of an accompanying person from the same household also complying with standard hygiene requirements.
6. Ability to self-administer prefilled enoxaparin injections after instructions received at the study center or availability of a person living with the patient to administer enoxaparin.

Exclusion Criteria:

1. Any acute or chronic condition posing an indication for anticoagulant treatment, e.g. atrial fibrillation, prior VTE, acute confirmed symptomatic VTE, acute coronary syndrome.
2. Anticoagulant thromboprophylaxis deemed necessary in view of the patient's history, comorbidity or predisposing strong risk factors for thrombosis:

   1. Any of the following events occurring in the prior 30 days: fracture of lower limb, hospitalization for heart failure, hip/knee replacement, major trauma, spinal cord injury, stroke,
   2. previous VTE,
   3. histologically confirmed malignancy, which was diagnosed or treated (surgery, chemotherapy, radiotherapy) in the past 6 months, or recurrent, or metastatic, or inoperable.
3. Any clinically relevant bleeding (defined as bleeding requiring hospitalization, transfusion, surgical intervention, invasive procedures, occurring in a critical anatomical site, or causing disability) within 30 days prior to randomization or sign of acute bleeding.
4. Intracerebral bleeding at any time in the past or signs/symptoms consistent with acute intracranial hemorrhage.
5. Hemoglobin \<8 g/dL and platelet count \<50 x 109 cells/L confirmed by recent laboratory test (\<90 days).
6. Subjects with any known coagulopathy or bleeding diathesis, including known significant liver disease associated with coagulopathy.
7. Severe renal insufficiency (baseline creatinine clearance \<30 mL/min calculated using the Cockcroft-Gault formula) confirmed by recent laboratory test (\<90 days).
8. Contraindications to enoxaparin therapy, including prior heparin-induced thrombocytopenia and known hypersensitivity.
9. Current use of dual antiplatelet therapy.
10. Participation in other interventional studies over the past 30 days.
11. Non-compliance or inability to adhere to treatment or lack of a family environment or support system for home treatment.

Answer: A