Misunderstandings of Venous thromboembolism prophylaxis Veerendra Chadachan Senior Consultant Dept of General Medicine (Vascular Medicine and Hypertension) Tan Tock Seng Hospital, Singapore
Case scenario Madam TAA is a 5' 3," 100kg 58 yo female She is admitted to have a right total knee replacement. Her past medical history includes hypertension and moderate COPD. No personal and family history of VTE. Her home medications include hydrochlorothiazide 25 mg po daily, spiriva and albuterol. She has stopped smoking 1 year ago.
Question 1 1. Which of following is NOT a known risk factor for VTE development for Madam TAA? a. Obesity. b. Hypertension. c. COPD. d. Total knee replacement surgery. e. Age 58 years
Question 2 2. What is the minimum amount of time Madam TAA should receive VTE prophylaxis? a. 2 days. b. 3 days. c. 5 days. d. 7 days. e. 10 days.
VTE = spectrum of DVT + PE Common clinical problem. Significant morbidity and mortality. Major impact on one s health. Economic burden on healthcare system.
VTE - Pathophysiology VTE is a complex (multifactorial) disease, involving interactions between various risk factors. Stasis Alteration in normal blood flow VIRCHOW S TRIAD Endothelial Injury Injury or trauma to the inside of the blood vessel Hypercoagulability Alternation in the constitution of blood causing blood to clot more easily
VTE - Incidence Annual incidence of VTE in general population 104 to 183 per 100,000 person-years Males 130 per 100,000 person-years Females 110 per 100,000 person years Arch Intern Med. 1998; 158(6):585-93. VTE prophylaxis Identify patients who are at increased risk of VTE.
Assessing VTE Risk Who should be assessed? ALL adult patients admitted into hospital Others: Preadmission for elective surgery Patient Groups Patients discharged from ED with significantly reduced mobility relative to normal state eg in a cast/boot following lower leg injury Pregnant and post-partum women
Outpatient and Inpatient VTE are Linked 74% of VTEs present in outpatients. 26% of VTEs present in in-patients. 42% of outpatient VTE patients have had recent surgery or hospitalization. Spencer FA, et al. Arch Intern Med 2007; 167: 1471-1475
Misunderstandings of VTE prophylaxis Unfortunately, VTE prophylaxis for high risk hospitalized patients is extremely underutilized due to historical misconceptions. 1. the belief that the overall incidence of VTE among hospitalized and postoperative patients is too low to consider prophylaxis; 2. fear of bleeding from anticoagulants; 3.unawareness that prophylaxis is effective at decreasing VTE-associated morbidity and mortality; 4. unawareness that broad application of prophylaxis may be cost-effective; and 5. perceptions that VTE is not a significant problem in their practice. 6. the belief that risk of VTE is limited to in-patient stay and doesn t extend into out-pt setting.
Misunderstanding 1. Overall incidence of VTE is too low to consider prophylaxis Incidence of VTE without prophylaxis 10 to 40% of medical or surgical hospitalised patients 40 to 60% following major orthopedic surgery. It has been estimated that 10% of hospital deaths are due to pulmonary embolism. Chest. 2004;126:338S 400S. Therefore, VTE is considered the number one cause of preventable death among hospitalized patients.
Misunderstanding 2. Fear of bleeding from anticoagulation Bleeding is viewed as an act of Commission. Development of VTE is not viewed as an act of Omission.
Misunderstanding 3. Broad application of VTE prophylaxis is expensive
Misunderstanding 3. Broad application of VTE prophylaxis is expensive In a population-based study, adjusted mean predicted costs over 5 years were found to be 2.5-fold higher for patients with VTE related to current or recent hospitalization for acute illness (US$62,838) than for hospitalized control patients ($24,464; P <0.001). Cost differences between cases and controls were greatest ($16,897) within the first 3 months. Am. J. Manag. Care. 2015;21:e255 e263
Misunderstanding 3. Broad application of VTE prophylaxis is expensive Similarly, the 5-year costs were predicted to be 1.5-fold higher for patients with VTE related to current or recent hospitalization for major surgery ($55,956) than for hospitalized control patients matched by the type of surgery ($32,718; P <0.001). Cost differences between cases and controls were again greatest ($12,381) in the first 3 months after the index date. Surgery. 2015;157:423 431.
Misunderstanding 4. VTE is not a significant problem in Asia Singapore studies suggest that VTE risk is increasing in our hospitalised patients. 0.079% (1989-1990) 0.158% (1996-1997) 0.454% (2002-2003)
Misunderstanding 5. VTE risk ends upon discharge from hospital VTE can occur for up to 3 months after total knee and hip arthroplasty 1 Hypercoagulability can persist for 4-6 weeks after hip fracture 2 Venous function was significantly impaired for up to 35 days following hip fracture surgery 3 1. White RH et al. Arch Intern Med. 1998;158:1525-1531. 2. Wilson D et al. Injury. 2001;32:765-770. 3. Wilson D et al. Injury. 2002;33:33-39.
Misunderstanding 6. Unaware that prophylaxis is effective in preventing VTE VTE Prophylaxis in 19,958 Medical Patients/ 9 Studies (Meta-Analysis) 62% reduction in fatal PE 57% reduction in fatal or nonfatal PE 53% reduction in DVT Dentali F, et al. Ann Intern Med 2007; 146: 278-288
VTE prophylaxis - Conceptual Framework All hospitalized patients must be routinely evaluated for VTE prophylaxis on admission. Patients should be reassessed within 24 hours of admission and whenever the clinical situation changes. All surgical patients, and all medical patients with significantly reduced mobility, should be considered for further risk assessment. VTE pharmacoprophylaxis involves a tradeoff between preventing thrombosis and causing bleeding When making tradeoffs, need to compare absolute risks of thrombosis and bleeding - VTE risk assessment - Bleeding risk assessment
VTE risk assessment models No consensus on what is best in clinical practice Individualized point-based scoring (quantitative) models Generally more rigorously validated in determining risk, but not in clinical practice Examples: Caprini Padua IMPROVE Grouping or bucket models Generally not as well validated in predicting risk, but easier to implement, Examples: NICE / NHS guidelines, Australia / New Zealand working group model Classic 3 bucket model Updated 3 bucket grouping model Although there are many tools for assessing thromboembolism risk, there is insufficient evidence to recommend one over the others. 13
Padua Prediction Score Padua Prediction Score one of the most validated prediction tool for assessment of VTE risk in medical patients. Score < 4 Low VTE risk, 0.3% risk of developing symptomatic VTE within 90 days. Score > 4 - High VTE risk, 11% risk of developing symptomatic VTE within 90 days. Cannot apply for critically ill patients.
Caprini VTE Risk Assessment tool
14
Updated 3 bucket Model More c/w AT9 guidelines
Bleeding risk assessment models
Pharmacological Prophylaxis Drug Class Unfractionated heparin LMWH Agents Unfractionated heparin Enoxaparin Dalteparin Preferred in patients with renal impairment Most commonly used agents Require dosage adjustment in renal impairment Factor Xa inhibitors Direct thrombin inhibitors Apixaban Rivaroxaban Fondaparinux Dabigatran Alternative for prophylaxis in post- hip or knee replacement Alternative for prophylaxis in post- hip or knee replacement and hip fracture surgery Alternative for prophylaxis in prophylaxis posthip or knee replacement Heparinoid Danaparoid Used in heparin-sensitivity or HIT
Pharmacological Prophylaxis Contraindications may include: Contraindications Active bleeding Thrombocytopenia (platelets < 50 x 10 9 /L) End stage liver disease (INR > 1.5) Treatment with therapeutic anticoagulant e.g. warfarin with INR > 2 Severe trauma to head or spinal cord, with haemorrhage in last 4 weeks
Mechanical Prophylaxis Devices that increase blood flow velocity in leg veins, reducing venous stasis. Device Graduated Compression Stockings (GCS) Anti-embolic Stocking Intermittent Pneumatic Compression Device (IPC) Foot Impulse Device (FID) Provide graduated compression, which is firmest at the ankle. Used mainly for ambulant patients Standard compression throughout. Used for bedbound or non-ambulant patients Inflatable garment wrapped around legs which is inflated by pneumatic pump. Enhances venous return Stimulates legs veins to mimic walking and reduce stasis. Used for immobilised patients
Mechanical Prophylaxis Contraindications may include: Contraindications Skin ulceration Lower leg trauma Morbid obesity (where correct fitting of stocking cannot be achieved) Massive leg oedema or pulmonary oedema due to CCF Stroke patients (avoid compression stockings) Significant PAD cannot use IPCs
Case scenario Madam TAA is a 5' 3," 100kg 58 yo female She is admitted to have a right total knee replacement. Her past medical history includes hypertension and moderate COPD. No personal and family history of VTE. Her home medications include hydrochlorothiazide 25 mg po daily, spiriva and albuterol. She has stopped smoking 1 year ago.
Question 1 1. Which of following is NOT a known risk factor for VTE development for Madam TAA? a. Obesity. b. Hypertension. c. COPD. d. Total knee replacement surgery. e. Age 58 years
Question 1 1. Which of following is NOT a known risk factor for VTE development for Madam TAA? a. Obesity. b. Hypertension. c. COPD. d. Total knee replacement surgery. e. Age 58 years
Question 2 2. What is the minimum amount of time Madam TAA should receive VTE prophylaxis? a. 2 days. b. 3 days. c. 5 days. d. 7 days. e. 10 days.
Question 2 2. What is the minimum amount of time Madam TAA should receive VTE prophylaxis? a. 2 days. b. 3 days. c. 5 days. d. 7 days. e. 10 days.
Conclusions VTE prophylaxis is justified, low-risk, and indicated in most hospitalized patients. Overall, VTE prophylaxis is under-utilized. Physician hesitation is due to misunderstandings. Appropriate prophylaxis should be delivered for an appropriate duration. Each hospital needs a standardized approach for VTE prophylaxis to improve compliance protocols, pre-printed orders, risk stratification, etc. Multi-disciplinary approach auditing
Thankyou for your kind attention