What are the anticoagulation guidelines for older adults?

Anticoagulation Guidelines for Older Adults

Anticoagulants should not be withheld from older adults based on age alone, and every hospital should implement a systematic strategy for venous thromboembolism prevention in this population. 1

Core Principle: Age Is Not a Contraindication

The American Geriatrics Society explicitly states that oral anticoagulants are underused in older patients despite their elevated thromboembolic risk. 1 Advanced age (≥80 years) should never be the sole reason to withhold anticoagulation. 2 Instead, decisions must incorporate bleeding risk factors, comorbidities, renal function, and quality of life considerations. 2

Risk Stratification for VTE Prevention

Surgical Patients

Older adults undergoing surgery face cumulative thrombotic risk from multiple factors: 1

• Age ≥60 years automatically elevates risk even for non-major procedures 1
• High-risk surgeries include gynecological, urological, major general, and major orthopedic procedures 1
• Additional risk factors include prolonged immobility, stroke, paralysis, prior VTE, active cancer, trauma (especially pelvic/hip/leg fractures), obesity, cardiac dysfunction, indwelling central venous catheters, inflammatory bowel disease, nephrotic syndrome, and estrogen use 1

Prophylaxis Recommendations by Procedure Type

For low-risk urological procedures (transurethral): prompt ambulation only 1

For major open urological procedures: LDUH, elastic stockings, IPC, or LMWH (Grade 1B) 1

For elective hip replacement: LMWH is preferred over adjusted-dose warfarin (INR 2.0-3.0) because it more effectively prevents asymptomatic VTE (Grade 1A). 1 Adjusted-dose heparin is an alternative but more complex to manage (Grade 2A). 1 IPC devices or elastic stockings may provide additional benefit (Grade 2C). 1

For hip surgery, total knee replacement, and major gynecologic surgery: Initiate warfarin several days before surgery, the evening before, or on postoperative day 1, continuing for ≥3 months or until ambulatory, targeting INR 2.0-3.0. 1 Note that fixed-dose warfarin 1 mg is ineffective for major orthopedic surgery prophylaxis. 1

Treatment of Established VTE

For proximal DVT, symptomatic calf vein thrombosis, and pulmonary embolism: Oral anticoagulation is indicated with INR target 2.0-3.0. 1

Duration of therapy: 1

• Initial symptomatic calf vein thrombosis: treat as proximal DVT
• Idiopathic proximal venous thrombosis: ≥6 months
• Recurrent thromboses: indefinite treatment
• Pulmonary embolism: 6 months (though optimal duration lacks randomized trial data)

Warfarin Dosing Adjustments for Older Adults

Elderly patients require approximately 1 mg/day less warfarin than younger individuals to maintain comparable INR levels. 2

For frail patients with low BMI (<18.5 kg/m²): Start at the lower end of the dose range (2 mg daily) with a target INR of 2.0 (range 1.6-2.5) rather than the standard 2.0-3.0 range. 2 Low BMI patients have reduced protein levels leading to greater free drug fraction, requiring dose reduction. 2

Direct Oral Anticoagulants (DOACs) in Older Adults

DOACs are associated with approximately 50% reduction in intracranial bleeding compared to warfarin, making them particularly advantageous in older adults. 2, 3 Meta-analyses and real-world data confirm DOACs are non-inferior to warfarin for efficacy and cause less major bleeding, especially intracranial hemorrhage. 3

DOAC-Specific Renal Contraindications

Absolute contraindications based on renal function: 2

• Dabigatran: CrCl ≤30 mL/min
• Rivaroxaban: CrCl ≤15 mL/min

Apixaban Dosing in Older Adults

For atrial fibrillation, apixaban 5 mg twice daily is standard, but reduce to 2.5 mg twice daily if the patient has ≥2 of the following: 4

• Age ≥80 years
• Body weight ≤60 kg
• Serum creatinine ≥1.5 mg/dL

In ESRD patients on hemodialysis, systemic exposure to apixaban is 36% higher when dosed post-dialysis compared to patients with normal renal function. 4

When to Consider Cessation

Do not cease anticoagulation based on frailty alone. 2 Cessation is appropriate when: 2

• Multiple unmodifiable bleeding risk factors coexist: severe anemia, recent MI, renal failure, balance problems from stroke/Parkinson's disease, fragile vasculature
• Quality of life considerations outweigh stroke prevention benefits in terminal illness
• The burden of monitoring, medication side effects, and bleeding risk exceeds benefit
• Loss of indication for anticoagulation

High-risk patients (ORBIT score ≥4 points) have 8.1% annual bleeding risk and require intensive monitoring rather than automatic cessation. 2

Monitoring Strategy

For Warfarin

High-risk patients (ORBIT ≥4): INR monitoring every 1-2 weeks 2

More frequent monitoring needed during: 2

• Fluctuations in diet
• Weight changes
• Concomitant medication changes
• Intercurrent illness

When starting dietary supplements (including collagen): Check INR within 3-7 days, then monitor more frequently for 2-4 weeks. 5

For DOACs

Routine laboratory testing is not required. 6 However, monitor renal function regularly, as half-life is prolonged with renal impairment (dabigatran half-life increases from 13 hours to 27 hours when CrCl drops below 30 mL/min). 2

Baseline testing before DOAC initiation should include: 7

• Creatinine (18% of patients in one study did not receive this)
• Complete blood count (31% did not receive this)
• Coagulation studies (67% did not receive this)

Follow-up visit within 1 month of DOAC initiation is recommended, though only 39% of patients in one study achieved this. 7

Perioperative Management

For low-risk procedures: Resume rivaroxaban or apixaban 24 hours postoperatively 2

For high-risk procedures: Resume 48-72 hours postoperatively 2

DOACs can be interrupted for planned procedures without bridging with LMWH, unlike warfarin. 6

Bleeding Management

For Life-Threatening Bleeding

Specific reversal agents: 6, 8

• Idarucizumab for dabigatran
• Andexanet alfa for apixaban and rivaroxaban

If specific agents unavailable: Consider prothrombin complex concentrates or activated prothrombin complex concentrates 6

For warfarin-related bleeding with elevated INR: Omit 1-2 doses and consider oral vitamin K₁ 1-2.5 mg if bleeding risk factors are present. 5

General Approach

The relatively short circulating half-lives of DOACs mean that time, local measures, and supportive care are the main response to major bleeding in most cases. 3

Critical Pitfalls to Avoid

• Do not cease anticoagulation solely based on age ≥80 years 2
• Do not ignore drug-drug interactions (NSAIDs, antiplatelet agents) that can be modified rather than stopping anticoagulation 2
• Do not fail to reassess bleeding risk regularly, as it is dynamic and changes over time 2
• Do not overlook that low BMI patients require dose reduction, not cessation 2
• Do not use fixed-dose warfarin 1 mg for major orthopedic surgery prophylaxis (it is ineffective) 1
• Do not prescribe dabigatran when CrCl ≤30 mL/min or rivaroxaban when CrCl ≤15 mL/min 2