Complications After Stroke Deprive Patients of Years of Optimum Health

Pauline Anderson

July 02, 2010

July 2, 2010 — Poststroke neurologic or medical complications deprive patients of an average 2 years of optimum disability-free health, according to a complex formula for calculating the impact of mortality and disability.

A new study using the formula, which determines disability-adjusted life-years (DALYs), found that the more complications ischemic stroke patients experience, the more years of optimum health they lose — for example, if they have only 1 complication, they lose 1.5 years, but if they have 2 or more complications, they lose 2.7 years, the study found.

The formula could be used to help allocate scarce healthcare resources to prevent stroke complications, said lead study author Keun-Sik Hong, MD, PhD, associate professor of neurology at Inje University, Goyang, South Korea.

"This study delineates the hazard of poststroke complications with a comparable and understandable measure," said Dr. Hong in an email. "The burden and interventional effect of diverse health conditions should be compared with a validated, comparable, and understandable metric for health system planning."

The study was published online July 1 and will appear in the August issue of Stroke.

Complication Types

For the study, researchers used data on patients enrolled in the Complication in Acute Stroke Study (COMPASS), a multicenter, prospective, observational study that evaluated poststroke complications for 1254 consecutive patients with acute ischemic stroke admitted to 4 university hospitals in South Korea from September 1, 2004, to August 31, 2005.

For each patient, researchers prospectively collected data, including baseline demographics, stroke severity and subtype, laboratory details, and postadmission neurologic and medical complications. Three-month modified rank scale outcomes, obtained by direct interview or by telephone, were available for 1233 patients (98.3%).

Neurologic complications included ischemic stroke progression, symptomatic hemorrhagic transformation, recurrent stroke, and seizure within 2 weeks of stroke onset. Medical complications included pneumonia, myocardial infarction, urinary tract infection, extracranial bleeding, pulmonary embolism, pyrexial illness, pressure sores, and fall within 4 weeks of stroke onset.

To quantify the extent of disease burden, the researchers used the DALY formula, which integrates both mortality (years of life lost due to premature death) and disability (years of healthy life lost due to living with a disability). One DALY lost equals a loss of 1 year of optimum health free of disability.

To illustrate the formula, Dr. Hong used the example of a 60-year-old stroke patient who has a residual disability weight of 0.6 (disability weight ranges from 0 to 1, with 0 being no disability and 1 being deceased). If that patient lived 8 more years and died at the age of 68 years, his life expectancy is 12 years shorter than that of the general population according to previous findings from the Framingham study. That patient’s DALYs lost would be the sum of life-years lost due to disability (0.6 × 8 = 4.8) and life-years lost due to premature death (12 years), for a total of 16.8 DALYs lost.

The DALY formula also factors in a 3% annual "future discount rate," said Dr. Hong. "The future discount means that the life-years lost in the future should be valued lower than the immediate life years lost — similar to an interest rate in economics."

The metric also includes the concept of age weighting, he noted. "That means that the life-years of the young, which is a highly productive age, should be more highly valued than those of infants and the elderly, which are ages with low productivity from the view point of economics," explained Dr. Hong.

The average DALYs lost due to a stroke in the study population was 3.82. About 34% developed any complication, whereas 20.8% developed neurologic complications and 24.0% developed medical complications. The most common neurologic complication was ischemic stroke progression (16.9%), and pneumonia was the most common medical complication (11.7%).

To delineate whether patients with more complications had more DALYs lost, researchers categorized them into those with no complications, those with 1 complication, and those with 2 or more complications. Of the 1233 patients, 230 (18.7%) had 1 complication and 200 (16.2%) had 2 or more complications.

The study found that the more complications patients experienced, the more DALYs lost they had. Compared with patients with no complications, those with 1 complication had 1.52 (95% confidence interval, 1.15 – 1.89; P < .001) more DALYs lost, and those with 2 or more complications had 2.69 (95% confidence interval, 2.18 – 3.20; P < .001) more DALYs lost. Patients with 2 or more complications had 1.18 more DALYs lost than those with 1 complication.

DALY calculations could be used for healthcare resource allocation. "Resources are limited and should be allocated based on a transparent cost-benefit analysis," said Dr. Hong. "The DALY is a widely accepted scale derived by a firm methodological ground."

The study authors used pneumonia, which deprives patients of an additional 2 years of healthy life, as an example of how information about such complications could help steer health policy. "Given a 5.6% incidence of pneumonia in acute stroke and an annual incidence of stroke of 795,000 in the Unites States, a nationwide implementation of the formal dysphagia screening and management program would save annually 44,520...healthy life-years in the United States."

DALY Advantages

The DALY formula has a number of advantages over conventional tools used to analyze the impact of stroke outcomes. Although other measures express increases of risk or odds, the DALY formula directly expresses life-years lost, which is more easily comprehended, said Dr. Hong.

"The DALY analysis measures the disease burden or intervention effect with a common metric of life-years lost or gained. Therefore, stroke burden and intervention effect can be compared more clearly and more transparently with other disease burden and interventions."

Because the study was restricted to patients admitted within 7 days of stroke onset, it may have missed complications that had already developed. Another limitation was that it was a hospital-based study, so its results cannot be extrapolated to the general Korean stroke population or to populations elsewhere.

In addition, the study did not capture all poststroke cognitive and emotional outcomes and so did not fully explore the neuropsychological impact of these complications. "My private opinion is that patients with more serious physical disability would have poorer cognitive and emotional outcomes," commented Dr. Hong. "Therefore, if these outcomes were incorporated into the DALY measure, stroke patients likely would have more life-years lost."

"Potent" Study

Asked for a comment, Philip Gorelick, MD, spokesperson for the American Heart Association/American Stroke Association, and John S. Garvin Professor and head director, Center for Stroke Research, Department of Neurology and Rehabilitation, University of Illinois College of Medicine, Chicago, called the study "very interesting," "potent," and "clever."

The study clearly spells out the toll of poststroke complications, said Dr. Gorelick. "We know that some patients will have a stroke recurrence; we know that some patients will develop seizures and hemorrhagic transformations; we know that others will get medical complications such as pneumonia, heart attack, urinary tract infections, and pulmonary embolism, but not many of us understand very well in a quantitative form the toll that these complications take."

Most healthcare professionals do not even think about the impact of poststroke complications, he added. "They think that these complications are par for the course and don't realize what it’s doing to the patient. This study demonstrates a way to quantify that and it's very, very important."

The study should serve as a "huge wakeup call" for clinicians, he said. "We really have to intensify our prevention of these complications and take them very seriously because they're not benign."

Dr. Gorelick agreed that the study could eventually spur a heavier emphasis on prevention as a more cost-effective use of health resources. "Once healthcare policymakers better understand this data, they're going to start insisting that we do a better job or we won’t get reimbursed."

Dr. Hong is involved in the design and/or is a site investigator of multicenter clinical trials sponsored by Korea Otsuka, Boryung, and Novartis Korea and received lecture honoraria from Sanofi-Aventis. For conflict of interest information for other authors, please see original article.

Stroke. Published online July 1, 2010.