Falls, frailty and atrial fibrillation: deciding on anticoagulation
A 78-year-old woman with permanent atrial fibrillation attends the falls clinic after two unwitnessed falls in six months, both while hurrying to the bathroom; neither caused injury. She lives alone, walks with a stick indoors and has troublesome daytime urinary urgency. Her medications are amlodipine 10 mg, bisoprolol 5 mg, aspirin 75 mg, sertraline 50 mg and ibuprofen gel, which she uses most days for knee pain. Blood pressure is 138/76 mmHg seated and 112/68 mmHg standing; pulse 78 and irregular. Weight 48 kg, creatinine 158 µmol/L, eGFR 24 mL/min/1.73 m², haemoglobin 121 g/L, platelets 210 ×10⁹/L. She has hypertension, type 2 diabetes and osteoarthritis but no myocardial infarction, stroke or peripheral arterial disease. Her daughter asks whether 'blood thinners' are now too dangerous.
1. Calculate her CHA₂DS₂-VASc and HAS-BLED scores and her Cockcroft–Gault creatinine clearance, showing your working. State whether you would anticoagulate and, if so, with which agent and dose.
Read the worked answer
Stroke risk. CHA₂DS₂-VASc: age ≥75 = 2, hypertension = 1, diabetes = 1, female sex = 1 → 5 (roughly 6–7% annual stroke risk untreated).
Bleeding risk. HAS-BLED: hypertension 1, age >65 1, antiplatelet plus NSAID 1 → 2 (a creatinine of 158 µmol/L does not score, as the renal criterion requires >200 µmol/L, dialysis or transplant). Her predicted major bleed rate is around 2% per year.
Renal function. Cockcroft–Gault: (140−78) × 48 / (0.815 × 158) = 23 mL/min, × 0.85 for female sex = ≈20 mL/min.
Decision. Anticoagulate. Untreated she loses about 4–5% absolute stroke reduction per year, several-fold more than her bleeding risk. Modelling suggests a patient would need hundreds of falls per year before anticoagulation became net harmful, so falls are an indication to modify risk, not to withhold treatment.
Agent and dose. Apixaban 2.5 mg twice daily. She meets two of the three dose-reduction criteria (weight ≤60 kg and creatinine ≥133 µmol/L; her age is 78, not ≥80). Standard-dose apixaban, rivaroxaban or edoxaban would over-anticoagulate her, and dabigatran should be avoided at this creatinine clearance.
2. Which of her current medicines would you change before she leaves the clinic, and why? Address both bleeding risk and the falls.
Read the worked answer
Stop aspirin. She has diabetes but no established vascular disease, so there is no secondary-prevention indication. Combining an antiplatelet with an anticoagulant roughly doubles gastrointestinal bleeding without adding stroke protection.
Stop regular topical NSAID. Systemic absorption from gel is low but non-trivial in a 48 kg woman on an anticoagulant; substitute paracetamol and, if needed, topical capsaicin. Oral NSAIDs should be avoided absolutely.
Review sertraline. SSRIs impair platelet serotonin uptake and increase bleeding, particularly GI. If her mood has been stable for a year, consider a slow taper; if treatment is still needed, continue it and add a proton-pump inhibitor rather than leaving her depressed and untreated.
Address the postural drop. Systolic pressure falls 26 mmHg on standing - reduce or stop amlodipine first, since bisoprolol is rate-controlling, then recheck lying and standing pressures. Investigate the urinary urgency (bladder training, review fluids, exclude infection), arrange strength and balance work, home-hazard assessment, visual check, vitamin D and a fracture-risk assessment. None of these replaces anticoagulation - they make it safer.
3. What monitoring would you arrange, and which findings at review would make you change or stop the anticoagulant?
Read the worked answer
Monitoring. No routine INR is needed. Check full blood count, renal and liver function at baseline and then at least every three months while creatinine clearance is around 20 mL/min, and after any acute illness, dehydration or new drug. Record weight at each review, since a further fall in weight does not change the dose (already reduced) but does change renal clearance. Confirm she understands to report black stools, unusual bruising, haematuria or head injury, carries an anticoagulant alert card, and avoids over-the-counter NSAIDs and aspirin.
Triggers to change.
- Creatinine clearance falling below 15 mL/min: stop apixaban (no licensed data) and discuss alternatives.
- A major bleed, especially intracranial: stop, reverse, and do not automatically restart - discuss with cardiology and consider left atrial appendage occlusion.
- A new interacting drug (strong CYP3A4/P-gp inhibitors such as clarithromycin, azoles, or enzyme inducers such as carbamazepine or phenytoin): consider dose review or a different agent.
- Recurrent falls with head injury despite modification: reassess but only stop after multidisciplinary discussion, documenting that the residual stroke risk is high.