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For Your Patients-Carotid Endarterectomy
Being Old and Poor May Elevate Risk for Worse Outcomes After Carotid Endarterectomy



DR. ERICA LEIFHEIT: “We need to better understand this population. Even when we stripped away the financial barriers there was still a disparity.”

An analysis of findings suggesting that elderly people who are dual-eligible for Medicare and Medicaid have worse outcomes after carotid endarterectomy points to the need to address health care disparities, study authors and independent experts said.

Medicare patients who are poor enough to also qualify for Medicaid have worse outcomes following carotid endarterectomy than patients who are covered by Medicare alone; they also have an elevated risk for readmission, stroke, and death.

That finding emerged from a new study that used “dual eligible” status as a window into the broader issue of health disparities.

The study, reported online September 28 in Neurology, was unable because of its design to pinpoint why these low-income elderly fare worse with carotid endarterectomy, though the researchers said, “challenges may include split accountability between Medicare and Medicaid programs and differences in socioeconomic and clinical characteristics of these patients.”

“We need to better understand this population,” said lead researcher Erica Leifheit, PhD, a research scientist and epidemiologist at Yale School of Public Health. Lack of health insurance coverage is considered a contributor to health disparities, but everyone in the study had health benefits, some twice over, meaning they had access to the surgery, Dr. Leifheit said, adding: “Even when we stripped away the financial barriers there was still a disparity.”

Dual-eligible patients are among the poorest of low-income elderly individuals. The study authors noted that more than 6.7 million US adults aged 65 or older depended on both Medicare and Medicaid coverage in 2015 to obtain medical services.

“Dual-eligible beneficiaries have lower socioeconomic status and a higher prevalence and total number of chronic conditions than those eligible for Medicare alone. They also account for a disproportionate amount of Medicare spending,” the study authors wrote.

At the same time, prior research has shown that “lower socioeconomic status is associated with higher rates of vascular risk factors, stroke incidence and mortality, and poor outcomes after certain vascular procedures.”

But the study authors noted that very few national studies have used dual-eligible status to assess outcomes for acute events or procedures, adding that not much is known in that regard when it comes to carotid endarterectomy (CEA), the most common vascular procedure done in the elderly.


To get at the question, the researchers analyzed data for fee-for-service Medicare beneficiaries aged 65 or older who underwent CEA at acute-care hospitals in the US between January 2003 and December 2010. The study excluded patients with concomitant major interventions (such as coronary artery bypass grafting) during the index admission and those who underwent both CEA and carotid stenting. Patients enrolled in both Medicare and Medicaid for at least one month of follow-up were considered dual-eligible. Data were obtained from the Medicare Inpatient and Denominator files under an agreement with the Centers for Medicare & Medicaid Services.

Study outcomes included in-hospital, 30-day, and one-year all-cause mortality; the composite of 30-day ischemic stroke or death; and 30-day all-cause readmission.

The study cohort included 53,773 dual-eligible patients and 452,182 Medicare-only beneficiaries who underwent CEA. The percentage of dual-eligible CEA patients increased from 10.1 percent in 2003 to 11.5 percent in 2010.

Compared with Medicare-only patients, dual-eligible patients were more likely to be women, non-white, have comorbidities (such as heart failure, renal failure, and diabetes), and have symptomatic carotid disease.

Outcomes for both of the groups improved over the time period included in the study, but outcome disparities persisted.

For each study year, dual-eligible patients versus Medicare-only patients had a longer mean length of hospitalization and a higher inflation-adjusted mean Medicare payment. Dual-eligible patients were also more frequently discharged to home care and skilled nursing/intermediate care facilities, and they had higher observed mortality and readmission rates. For instance, in 2010, the rate of 30-day ischemic stroke or death was 3.2 percent for the dual-eligible group compared to 2.6 percent for the Medicare-only patients. For one-year all-cause mortality, the rate was 9 percent versus 5.8 percent.

Over the course of the study, dual-eligible patients, compared to Medicare-only patients, had a 45 percent elevated risk of in-hospital mortality; 14 percent greater risk for 30-day ischemic stroke or death; 26 percent increased risk for 30-day all-cause mortality; 32 percent greater risk for 30-day readmission; and 35 percent greater risk for one-year all-cause mortality.

“Our results indicate a need to better understand factors contributing to poorer outcomes for dual-eligible patients,” the researchers concluded.

Because the study was based on hospital data, it was not possible for the researchers to consider a number of factors that may influence health outcomes, including low education, lack of social support, and barriers, such as lack of transportation, to accessing follow-up care.

Also, due to the lack of detailed clinical information in the hospital data that was analyzed, it was impossible to completely adjust the statistics for in-patient medical complexity, the report said. Medicaid eligibility and services vary from state to state, and the researchers were not able to say how program differences may have influenced the services patients received.


DR. LIDIA MOURA: “Having access to a procedure or having access to insurance coverage does not necessarily produce good outcomes. Giving access to care is just the first step in improving care, but its not enough.”

Since the data combined race and ethnicity into one variable, researchers were unable to consider those factors separately in their analysis, Dr. Leifheit said. She added that her team hopes to explore the question of disparities further by using Medicare data for out-of-hospital services related to CEA.


Lidia Moura, MD, MPH, a health services researcher who is director of the NeuroValue Health Services Research Lab at Massachusetts General Hospital, said that while the new study on dual-eligible elderly leaves many questions unanswered it does underscore the fact that “success is not enough to improve outcomes.”

“Having access to a procedure or having access to insurance coverage does not necessarily produce good outcomes,” said Dr. Moura, assistant professor of neurology at Harvard Medical School. “Giving access to care is just the first step in improving care, but it's not enough.”

She said getting people safely through hospitalization is one thing, “but once they are home, are they going to come back for care?”

She said research that digs into the root causes of health outcomes disparities can help health care planners and policymakers better devise programs to address the needs of the most vulnerable patients, whether it's more attention on patient education — for example, ensuring that they understand discharge information and the need to take prescribed medication — or stepped-up efforts to check on patients and make sure they return for follow-up appointments.

Dawn Kleindorfer, MD, FAAN, professor of neurology at University of Cincinnati, said there is only much that can be gleaned from administrative databases such as the one used for the CEA study. They are “pretty limited on what you can know about the individual patient,” she said. Dr. Kleindorfer said the dual-eligible population, the poorest of the elderly, may have been sicker to begin with and had more disability, something not necessarily reflected in diagnostic coding for hospitalizations.

The severity of diabetes, the medications people are taking, and their blood pressure control all are “factors that influence vascular health,” she said. Differences in outcomes need to be examined from multiple perspectives, from surgical care to medical management surrounding a procedure, to organization and availability of outpatient services, she added.

“There are a lot of poor people in our country and there are a lot of poor people not doing well,” Dr. Kleindorfer said. “It's important to figure out why.”

Eric M. Cheng, MD, MS, FAAN, associate professor of neurology at University of California, Los Angeles, said the new study adds to a body of literature indicating that dual-eligible Medicare patients have worse outcomes, particularly when it comes to chronic conditions.

“We know that the dual eligible are sicker and poorer than Medicare beneficiaries. But dual beneficiaries may not obtain the true benefits of both (forms of health coverage) because the systems are independent of each other,” he said.

Dr. Cheng said the elevated risk for readmission, stroke, and death in the dual-eligible patients who underwent carotid endarterectomy suggests there needs to be better coordination of care throughout the treatment process.


DR. ERIC C. CHENG: “We know that the dual eligible are sicker and poorer than Medicare beneficiaries. But dual beneficiaries may not obtain the true benefits of both (forms of health coverage) because the systems are independent of each other.”

“One of the most vulnerable periods in a patient's life is the transition from hospital to out of hospital. We may not have a great way to coordinate transition of care,” he said.

Ethan Halm, MD, professor of internal medicine and clinical sciences at University of Texas Southwestern Medical Center, has studied disparities in outcomes for carotid endarterectomy using Medicare data for New York. He found that minorities were more likely to be cared for by lower volume surgeons and hospitals, which could affect quality of care and lead to worse outcomes.

Dr. Halm said whether health disparities are studied through the lens of race/ethnicity or dual eligibility, the underlying issue is the same.

“It's like looking at different views of the elephant. The elephant is social disadvantage.”


• Leifheit EC, Wang Y, Howard G, et al. Outcomes after carotid endarterectomy among elderly dual Medicare-Medicaid-eligible patients Neurology 2018; Epub 2018 Sept 28.