OAC Prescribing in the ED Spurs on Long-term Use in AFib

Patrice Wendling

December 11, 2019

Prescribing an oral anticoagulant (OAC) to lower-risk older adults with atrial fibrillation in the emergency department (ED) was associated with markedly higher long-term OAC use and improved outpatient follow-up, a new study indicates.

In univariate analyses, 71.8% of patients who received an ED prescription and were alive at 6 months filled a prescription for an OAC versus 36.8% of those discharged without an ED prescription (P < .001).

After propensity-score weighting, there was a 30.6% absolute increase in filling an OAC prescription (67.8% vs 37.2%; P < .001) and the number needed to treat (NNT) was 3.

Three-fourths of patients who received an ED prescription filled it within 2 days of discharge. The median time to first fill was 1 day versus 28 days in the no-prescription group (mean, 12 days vs 76 days).

The ED encounter is a teachable moment with patients, Clare Atzema, MD, MSc, Institute for Clinical Evaluative Sciences, Toronto, Canada, told theheart.org | Medscape Cardiology.

"Saying to a patient when they've been waiting for long hours, their heart's been racing, and maybe they've had a bit of chest pain, 'here's a prescription' is much more influential than if you have two to three weeks to see your family doctor and you felt totally fine the whole time and then they say, 'you have to be on blood thinners and if you fall down the stairs or cut yourself, you're going to bleed like crazy,' " she said. "That's a whole different kettle of fish than if you get it in the emergency [department] and someone says it will stop you from having a stroke."

In addition, the ED prescription serves as "sort of a reminder and also a reassurance" to other physicians, she added.

In the paper published online December 9 in the Canadian Medical Association Journal, Atzema and colleagues noted that although suboptimal use of oral anticoagulants is well documented in atrial fibrillation, information on ED initiation of OAC is limited. The advent of direct oral anticoagulants (DOACs) may improve ED physicians' willingness to start a long-term medication that can cause bleeding, but current usual care remains referral to a longitudinal provider.

Among the study's 2132 patients, aged 65 or older, seen at 15 hospitals in the province of Ontario, prescribing rates for OAC in the ED varied widely across hospitals, from 7.3% to 38.2%.

"It's all about access," Atzema explained. "If you know the person is going to see another doctor and it's not going to be three weeks before they manage to get in or longer and they can advocate for themselves, then we are much more likely to initiate these drugs. Because otherwise you're starting them on a high-risk drug in some ways and they can bleed and you're sending them off into the great blue yonder."

In all, 1296 had follow-up care within 7 days — 10% with a cardiologist, 10.7% an internist, and 40.1% a family medicine physician. Within 30 days of the appointment, 39%, 40.4%, and 32.3%, respectively, filled a prescription for an OAC.

Prescription fill rates after a follow-up appointment were similar among provider types for patients who received an ED prescription, while the range was wider for the no-prescription group: cardiology (62.5% vs 33.5%), internal medicine (68.3% vs 34.2%), and family medicine (61.1% vs 22.2%).

"This result suggests that emergency department prescribing was associated with an increase in primary prescribing rates by primary care providers, to levels similar to those of cardiologists," Atzema and colleague write.

Despite increasing the proportion of patients receiving OACs, however, there was no reduction in deaths or strokes. This may be due to low event rates, initiation of OAC in the no-prescription group, and OAC discontinuations in the ED-prescription group, which was expected because persistence with warfarin as well as the newer DOACs is known to wane over time, Atzema said.

Indeed, the absolute increase in OAC prescription fills dropped to 23.2% and the NNT increased to 4 at 1 year (63.7% vs 40.5%; P < .001). "It's not really that surprising that this group didn't adhere as well because we don't have a relationship with the patient; they don't come back to us," she said.

Atzema pointed out that patients with an ED prescription, however, had numerically fewer strokes of any type at 1 year (6 vs 18) and 2 years (7 vs 37) and fewer bleeding events at 6 months (6 vs 10), 1 year (9 vs 18), and 2 years (13 vs 31). No strokes occurred in the study at 6 months.

Commenting on the study for theheart.org | Medscape Cardiology, Anil K. Gehi, MD, from the University of North Carolina at Chapel Hill, said, "It's an interesting finding. I think the thing that concerns me about it is that they're kind of presuming that the ED physician is having any sort of a detailed, shared decision-making type conversation with the patients. That's certainly something that's advocated for and is even contained in our quality assessments of treatment of atrial fibrillation."

Atzema agreed that shared decision-making is limited in the ED, but pointed out that the retrospective analysis included only low-risk patients eligible for OAC, having excluded patients with relative contraindications to OAC or perceived at high risk, including nursing home residents and those with a history of major cancer, hemorrhagic stroke, or gastrointestinal bleeding, or a HAS-BLED score of 4 or higher.

She suggested that a default strategy of short-term anticoagulation therapy initiated in the ED would provide for shared decision-making and address HAS-BLED risk factors if coupled with an appointment with a longitudinal care provider who decides whether to renew the prescription.

"We need an actual system where the patient isn't the conduit," she said. For example, "If you work in the VA, you can probably get an appointment from the ED by looking at the cardiology appointment system, so the emergency doc knows, okay, this patient is going to be seen within exactly six days because I can see the appointment time and I'm happy to start this."

While Atzema said her institution has moved to this default strategy, Gehi and colleagues are focused on specialized atrial fibrillation clinics, where trained providers can discuss major risk factors as well as patient preferences, their tolerance for risk, and ability to afford therapy, which is a more pressing concern in the United States.

"Many patients don't need to be admitted and we are very admirable of the way they handle things in Canada, where most patients are discharged," he said. "But the thing that's critical is that there be a very early follow-up for these patients so that a detailed shared decision-making conversation can happen and the anticoagulation can get started there. We actually don't prefer necessarily that the ED physician do that because as long as they're having an early follow-up appointment within a few days, the incremental risk of a stroke is pretty negligible."

"I think this kind of analysis shows that there are probably many different strategies to do this but there needs to be a step back and say 'what would be the ideal way to do this' and I don't know if a prescription in the ED is necessarily the ideal way," Gehi said. "It may be one approach, but it may not be the ideal way."

The study was supported by the Canadian Stroke Prevention Intervention Network, which was funded by a Canadian Institutes for Health Research grant under the Institute of Circulatory and Respiratory Health. Atzema was supported by a midcareer investigator award from the Heart and Stroke Foundation of Ontario, the Practice Plan of the Department of Emergency Services at Sunnybrook Health Sciences Centre, and the Sunnybrook Research Institute. Gehi reports r esearch support from the Bristol-Myers Squibb Foundation.

Can Med Assoc J. 2019;191:E1345-54. Full text

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