Mining the Gap: Researchers Dig for Data to Reduce Disparities in Atrial Fibrillation Treatment

Black people with atrial fibrillation (AF) experience vastly higher rates of serious coronary events, so it’s not surprising that a growing number of clinical studies are aggressively tackling the complex issues around the impact of race—as well as gender—on management and outcomes of the heart rhythm disorder.

Paradox prompts questions

Researchers refer to it as the “AFib Paradox”—the fact that studies have consistently reported a lower occurrence of AF among blacks compared with whites despite African Americans experiencing so many of the adverse events associated with the disease, including stroke, heart failure, hypertension and diabetes. But the “less AFib–more adversity” irony is one of many disparities to emerge from studies that have examined differences in the delivery of healthcare to blacks vs. whites and men vs. women. Indeed, why are blacks with AF who are hospitalized for heart failure less likely to be prescribed warfarin at discharge than whites, despite American College of Cardiology/American Heart Association and Heart Failure Society of America recommendations for anticoagulation therapy? And why are women, who have higher rates of hospitalization than men following AF ablation, less likely to undergo repeat ablation or cardioversion as a means to restore rhythm?

“I don’t think we can necessarily pass judgment on the healthcare system every time we see disparities based on race or sex,” offers Mintu Turakhia, MD, assistant professor of medicine at Stanford University and director of cardiac electrophysiology at the Palo Alto VA Health Care System. “Instead, these gaps tell us that we need to take a deeper dive into why they’re occurring, and those questions can only be answered through more [treatment] preference-based studies.”

No study has done more to spotlight the magnitude of those gaps than ARIC (Atherosclerosis Risk in Communities).

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In its latest analysis of data collected by epidemiologists over the past 20 years, the study found that blacks with AF have nearly double the risk of stroke, heart failure, coronary heart disease and mortality from all causes compared with whites (JAMA Cardiol 2016;1[4]:442-50). While researchers were well aware African Americans faced an increased risk of stroke, what surprised them were the findings that heart failure, coronary heart disease and mortality pose equally as great health dangers. Jared Magnani, MD, an associate professor of medicine at the University of Pittsburgh School of Medicine and lead author of ARIC, puts the numbers in context: “For me, they’re a loud and clear signal that we are missing profound opportunities to prevent adversity in blacks with atrial fibrillation,” he maintains. “There has been significant social strife by race over the past summer, and [the United States] is far from done grappling with how it addresses and cares for its most vulnerable citizens. That’s where our interventions are most imperative and where we can make the most significant difference.”

The goal of improving the quality and consistency of healthcare delivery regardless of race is also writ large in the work of Kevin Thomas, MD, director of health disparities research at Duke Clinical Research Institute and author of several studies in the field. Anticoagulation therapy is a case in point. One of his investigations reported that black patients with AF hospitalized for heart failure were 24 percent less likely to receive guideline-recommended warfarin at discharge compared with white patients—a finding Thomas and colleagues described as “concerning” in light of the black population’s significant risk of thromboembolic stroke (J Am Heart Assn 2013;2[5]:e000200). “One of the things my group is working on is trying to understand how decisions are made about anticoagulation therapy at both the provider and patient levels,” he says. “And we think that empowering patients to take control of their care as well as educating providers and holding them accountable for quality metrics are tenable solutions to the problem. Quality, theoretically, doesn’t have a race or gender to it.”

In an era of value-based medicine and accountable care, Thomas’s AF-heart failure study—which analyzed more than 135,000 hospitalizations from 2006 to 2012—also has cost implications. It found, for example, that black patients had lower in-hospital mortality and longer lengths-of-stay compared with whites. As for possible reasons why blacks remain hospitalized longer, Thomas and co-investigators cited complicating comorbidities and difficulties with getting their symptoms under control and arranging for in-home care. “The rising costs associated with hospitalizations for AF and [heart failure] make decreasing [length of stay] while reducing rehospitalization rates an important hospital performance indicator,” they wrote.

Measuring the gender gap

Many of the same health delivery issues affecting blacks with AF are transferable to women. A study published in the Journal of Cardiology underscored the gender gap. It found from an examination of nearly 6,000 people with AF (42 percent women) that women have higher rates of mortality and ischemic strokes than men, yet women are less likely to be prescribed anticoagulation therapy (76.8 percent vs. 82.5 percent) (online June 1, 2016). Lead author Natasha Kassim, MD, an internal medicine resident at the University of Pittsburgh School of Medicine, says she’s not ready to concede the existence of a dual treatment standard from its findings. Instead, she believes “we should be saying to prescribing physicians, ‘Think a little harder about the risks and benefits of anticoagulation medicine because we know that women have much higher stroke risk scores.’”

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Kassim cites another example of a treatment imbalance. “Women in our study were much more likely to get atrioventricular-nodal ablation, followed by pacemaker implantation, which is more of a rate control strategy, while men were much more likely to get AFib ablation or cardioversion, which is more of a rhythm control strategy,” she points out. “That suggests to me that the way we approach this type of procedural care for men and women is very different, and is another important area we need to carefully consider.”

Some of those same murky waters were stirred up by another study published in 2016. Turakhia and colleagues examined the medical claims of 45 million patients to find that, while women have higher rates of hospital admissions after AF ablation than men and are more likely to have a procedural complication, they are less likely to undergo repeat ablation or cardioversion (JACC Clin Electrophysiol 2016;2[6]:703-10). “There’s an interesting contradiction here,” emphasizes Turakhia. “Women with AFib are entering the hospital more often than men after ablation, but they’re not getting other interventions to sustain rhythm control. There could be many good reasons for this. But at the very least it suggests that we need to do a lot more work to understand the facilitators and barriers of rhythm control strategies in women compared to men, and that we need to get a better sense of what the differences are in terms of treatment preferences.”

To be sure, researchers tackling race and gender issues mince few words about the need for more inclusive studies that better target people of color, many of whom are poor and about as likely to be enrolled in a clinical trial as they are to spend an evening in the Lincoln Room of the White House. As Elsayed Z. Soliman, MD, and colleagues wrote in 2009, “Current understanding of the pathophysiology and epidemiology of atrial fibrillation is based primarily on studies in White populations of European ancestry with limited data on the non-White populations” (Future Cardiol 2009;5[6]:547-56). They found a tight link between this “AF underascertainment among different racial and ethnic groups” and the oft-reported paradox of black individuals having a lower AF burden than whites.

“The fact is clinical research in general and cardiovascular research in particular has faced tremendous challenges recruiting and studying cardiovascular diseases in racial minorities,” declares Magnani, of the University of Pittsburgh School of Medicine. “Because these are people with fewer economic and social resources and the greatest risk for adversity, we need to make a more comprehensive effort to focus on, coordinate and build our clinical trials around them to ensure our findings are generalizable.”