Wednesday, May 6, 2015

Anticoagulation in Elders who Fall

If you had suggested to me only a short time ago that older people who fall should be taken off of anticoagulation, I would not have hesitated to agree. After all, first, do no harm, right? And isn’t the adage “less is more” absolute in geriatric medicine? But if there is one message I have learned through my internal medicine and geriatrics training, it is to always question “absolutes.” 

Case 
Mr. A was 91 years old when I first met him and when I took him off warfarin, which he was taking for atrial fibrillation.  He had many falls, lived alone, and required a walker to walk steadily but often did not use it in his very cluttered home. One week later, he fell right in front of our office sustaining a broken nose and I patted myself on the back. One month later, he awoke with aphasia and was admitted to the hospital for suspicion of stroke.  Thankfully, his event cleared within 24 hours, but the message it conveyed cued me to look further into the data we have on anticoagulation and falls – bringing me to the question, "In older adults with atrial fibrillation who are at high risk of falling, does bleeding on anticoagulation or stroke without it portend the greater morbidity/mortality?"


Risk of bleeds with falls 
Only one-third of patients who qualify for anticoagulation for atrial fibrillation receive it, with falls being listed time and again by primary care physicians as one of the top reasons for not starting or stopping this treatment. But what is the risk of major bleeding, especially of intracranial bleeding, in patients at high risk of falls? After all, the data is clear that anticoagulation worsens the risk of spontaneous intracranial hemorrhage. Hemorrhage also increases with age regardless of anticoagulation, so a knock on the head while on blood thinners could only possibly skyrocket that risk, right? Not necessarily.  In 2012, a prospective cohort study of over 500 patients discharged on oral anticoagulants found no significant difference in risk of major bleeding - including intracranial hemorrhage - at one year between those at high risk of falls and those who were not. (1)  One limitation was that there were very few major bleeding events and even fewer fall related bleeds (three!) Also, the average age in the study was 71 years, so this may not be applicable to our frail 80 and 90 year olds who are more likely to bleed. 

Risk of stroke without anticoagulation 
If bleeding and stroke rates both increase with aging, how do we balance the two? And just how large is the stroke risk without anticoagulation? Atrial Fibrillation Investigators (AFI) found that the average risk of first stroke for a patient >65 years old with at least one risk factor  is 5.7% per year, and by age 75 that risk rises to 8% per year (2). And in patients with only one risk factor for stroke, age greater than 75 demonstrated the strongest risk prediction (3). Anticoagulation with warfarin has been shown to historically lower that risk by at least two-thirds (2). So, how does this stack up to the risk of major morbidity and mortality from bleeding? Using pooled data from major atrial fibrillation trials, a decision analytic modeling study showed that a patient would have to fall 295 times per year for the risk of warfarin therapy to outweigh the benefit of stroke prevention (4). But is this just fancy math? Maybe not. A database study of over 20,000 Medicare beneficiaries found that despite higher incidence of intracerebral hemorrhage in patients identified as high risk for falls, if they also had at least a moderate stroke risk (CHADS=2), anticoagulation with warfarin was protective of mortality (5). While an obvious limitation is the data extraction using billing codes, a strength of this study over other studies described was the average sample age of 80 years. 

Novel Oral Anticoagulants (NOACs) – throwing a wrench in the works? 
But just as I’m finally getting comfortable with the data on warfarin, we have new agents with new risk profiles. Plus, they come with the caveat that if your patient suffers an intracranial hemorrhage when on a NOAC, there is no antidote to reverse it. Yet thankfully, the data we have points that the intracranial hemorrhages sustained on NOACs are fewer and less severe – possibly due to the shorter half-life of the drugs and quicker wash-out even despite not having an antidote (6). So, in spite of the highly discussed fear of lack of antidote, anticoagulation in our older patients with atrial fibrillation at risk of falls still seems in favor. 

Conclusions and Caveats 
The data is mounting that providing anticoagulation for patients with atrial fibrillation regardless of age and risk of falling is safer than withholding it, although most of the data excludes our oldest old and frailest frail. In the future, greater use of anticoagulation in this population will help us study the risks and benefits, and guide treatment decisions. Perhaps, the most astonishing point I learned from this exercise was the value of rechecking your gut reaction with available literature as a guide, keeping in mind that the application of the data lies somewhere in the marriage of the art and science of medicine. That is the essence of evidence-based medicine.  

References:
1. Donzé J, Clair C, Hug B, et al. Risk of falls and major bleeds in patients on oral anticoagulation therapy. Am J Med. 2012 Aug; 125(8):773-8.
2. Risk factors for stroke and efficacy of antithrombotic therapy in atrial fibrillation. Analysis of pooled data from five randomized controlled trials. Arch Intern Med. 1994 Jul 11; 154(13):1449-57.
3. Olesen JB, Lip GY, Hansen ML, et al. Validation of risk stratification schemes for predicting stroke and thromboembolism in patients with atrial fibrillation: nationwide cohort study. BMJ. 2011 Jan 31; 342:d124.
4. Man-Son-Hing M, Nichol G, Lau A, Laupacis A. Choosing antithrombotic therapy for elderly patients with atrial fibrillation who are at risk for falls. Arch Intern Med. 1999 Apr 12; 159(7):677-85. 
5. Gage BF, Birman-Deych E, Kerzner R, et al. Incidence of intracranial hemorrhage in patients with atrial fibrillation who are prone to fall. Am J Med. 2005 Jun; 118(6):612-7.
6. Caldeira D, Barra M, Pinto FJ, et al. Intracranial hemorrhage risk with the new oral anticoagulants: a systematic review and meta-analysis. J Neurol. 2015 Mar; 262(3):516-22.
Photo courtesy Martin Cathrae 

by: Mallory Otto, MD, Geriatrics fellow, Icahn School of Medicine at Mount Sinai.

This post is part of the #GeriCases series, in which we discuss a clinical case in geriatrics and palliative medicine and the attempt to provide patient-centered care with the use of best available evidence. 
Ravishankar Ramaswamy, MD
@RavRamaswamy
Section Editor, #GeriCases

3 comments:

Troye Wallett said...

This has been something that has bothered me for a long time so thank you for this post. The other question that I have is, does Aspirin in 80 and 90 years olds help for primary prevention of CVA.
What if they have had a TIA?

It feels like we over estimate the risk of bleed and under estimate the risk of stroke in this population.
So thanks again for this article.

Troye Wallett
www.genwisehealth.com.au

Lynn said...

Just wanted to say thanks for this! I am printing it off for our intern. I'm attending on Palliative Care this week. We are about to see an older man with afib and high CHADS score, not anticoagulated due to fall risk, who is in the hospital with a stroke.

Anonymous said...

You mention that there are no specific antidotes, yet available to these newer drugs but there are many in the pipeline - do you think this will change the management?

new antidotes: http://www.bmj.com/content/350/bmj.h1679/rapid-responses