The American Heart Association Stroke Outcome Classification: Executive Summary
Stroke remains one of the major public health problems in the United States today, with approximately 500 000 new or recurrent cases occurring each year.1 About 4 000 000 persons alive today have survived a stroke and have some neurological deficits. Although the magnitude of healthcare resources used to treat and rehabilitate stroke survivors is considerable, to date a standardized, comprehensive classification system to document the resultant impairments and disability has not been developed.
Successful management of any disabling disease, including stroke, should benefit from the use of a classification system to judge the impact of treatment, particularly emerging therapies. Participants in the Methodologic Issues in Stroke Outcome Symposium2 determined that the complex nature of stroke recovery demands clarification of its natural history and classification of the variable patterns of functional recovery. For stroke survivors to receive the best care, a comprehensive stroke outcome classification system is needed to direct appropriate therapeutic interventions.3 Building on the work and recommendations of the Stroke Outcome Symposium, the American Heart Association Classification of Stroke Outcome Task Force has worked to develop a valid and reliable global classification system that accurately summarizes the neurological impairments, disabilities, and handicaps that occur after stroke.
The development of a stroke outcome classification system is predicated on the belief that neurological deficits often lead to permanent impairments, disabilities, and compromised quality of life.4 5 6 Although a person’s ability to complete daily functional tasks is thought to be largely dependent on and often limited by the type and degree of impairment, additional factors are often relevant in the ultimate determination of functional outcome.7 8 9 Thus, a classification of stroke outcome should include the broad range of disabilities and impairments as well as the relationship of disability and impairment to independent function.
It is important to underscore that impairment alone does not define level of disability. In a study of stroke survivors10 it was determined that although a disability is most directly influenced by impairments, current stroke scales that measure impairments only partially explained the level of disability, handicap, or quality of life for those surviving at least 6 months. Some persons adapt well to many and/or severe impairments caused by stroke. Others with only minimal neurological impairments can be severely disabled. Many factors determine function, including the influence of poststroke rehabilitation training and the physical and social environments.
Approach to Stroke Assessment
The schema for the stroke outcome classification score presented here is conceptually similar to the New York Heart Association functional and therapeutic classification of patients with diseases of the heart framework.11 However, unlike heart disease, in which the primary limitation is impairment of physical activity due to chest pain, shortness of breath, and fatigue, stroke impairs many critical neurological functions, resulting in a greater number and broader range of physical and social disabilities. The AHA Stroke Outcome Classification (AHA.SOC) score (Figure⇓) classifies the severity and extent of neurological impairments that are the basis for disability. The classification also identifies the level of independence of stroke patients according to basic and more complex activities of daily living both at home and in the community. The classification score is meant to describe the limitations resulting from the current stroke. It is not an evaluation of disabilities caused by other neurological events. Furthermore, it is a summary score. The task force recommends that clinicians support their rating decisions with standardized assessment instruments whenever possible.
Components of the AHA Stroke Outcome Classification Score
Classification of Neurological Impairments
The first area of assessment in the AHA.SOC score is the evaluation of neurological impairment. A complete clinical examination is the basis for documenting the major domains of neurological impairment.12 In this classification schema the number of affected domains is recorded as well as severity of impairments.
Potentially affected neurological domains are
Motor: Motor impairments are the most prevalent of all deficits seen after stroke, usually with involvement of the face, arm, and leg, alone or in various combinations. Motor functions assessed in the AHA.SOC include cranial nerve function (including speech and swallowing), muscle power and tone, reflexes, balance, gait, coordination, and apraxia.
Sensory: Sensory deficits range from loss of primary sensations to more complex loss of perception. Patients may describe numbness, tingling, or altered sensitivity. The more complex sensory losses include astereognosis, agraphia, and extinction to double simultaneous stimuli.
Vision: Stroke can cause monocular visual loss, homonymous hemianopia, or cortical blindness.
Language: Dysphasia may be exhibited by disturbances in comprehension, naming, repetition, fluency, reading, or writing.
Cognition: Stroke can cause impairments in memory, attention, orientation, calculation abilities, and construction. It is important to assess ability to learn and retain new information in the cognitive evaluation.
Affect: Depression is the most common affective disturbance seen after stroke. It tends to be observed more often in the months after stroke than during the acute event. Symptoms include loss of energy, lack of interests, loss of appetite, and insomnia.13
The domains of stroke impairments are documented both in the number and severity of the neurological deficits observed. When >1 domain is affected, severity is defined by the most impaired domain. The categories for the number of domains involved after stroke are Level 0, no domains impaired; Level 1, 1 domain impaired; Level 2, 2 domains impaired; and Level 3, >2 domains impaired. For stroke severity, impairment is classified as being either Level A, minimal or no neurological deficit due to stroke in the above domains; Level B, mild/moderate deficit due to stroke; or Level C, severe deficit due to stroke.
The neurological examination is the basis for determining neurological impairments in the AHA.SOC score. However, the task force recommends that clinicians support their rating decisions by using standardized assessment measures whenever possible. The Appendix describes several available, well-documented assessment instruments that have been tested in stroke populations. This listing is suggestive and not all-inclusive of other available measures.
Classification of Functional Disabilities and Handicap
The second major area of assessment in determining the stroke outcome classification score is the evaluation of function in terms of resultant disability. Disability is defined as “any restriction or lack of ability to perform an activity in a manner or within the range considered normal for a human being.”4 The basic self-care tasks are feeding; grooming; dressing; bathing; toileting, including sphincter control; and mobility, including transferring from place to place. These are called basic activities of daily living (BADL). Independence in BADL could enable the stroke patient to live at home with help from family or community providers for meals and other household tasks as needed. More complex activities of daily living are called instrumental activities of daily living (IADL). These tasks are performed to maintain independence in the home and community and include shopping, using transportation, telephoning, preparing meals, handling finances, and maintaining a household. Independence in these activities enables the stroke patient to be discharged to home without being dependent on others. Other instrumental activities of daily living that affect quality of life are work skills, religious activities, and leisure-time and recreational activities (see Appendix).
Application of the AHA Stroke Outcome Classification Score to Sample Cases
The following cases illustrate the decision-making process and use of the AHA.SOC in assessments of 3 stroke patients.
Case 1: A 62-year-old man has an ischemic infarct in the left hemisphere. Neurologically he is cognitively intact, not depressed, and able to communicate. He has no residual weakness or sensory loss. Three months after the stroke he is living independently at home without healthcare assistance for basic daily activities. He manages routine household maintenance and needs assistance only with community activities such as shopping and banking. The stroke classification score for this patient is number of domains impaired=0; stroke severity=A; functional classification=Level II. AHA.SOC score=0.A.II.
Case 2 is a 74-year-old woman with a large-vessel infarct in the right hemisphere. Neurologically she has the following residual impairments: partial hemianopia, facial palsy, and sensory loss and weakness in the upper and lower left extremities. She is not depressed and is cognitively intact. She lives at home with professional home healthcare assistance. She requires the assistance of another person to access the community. She is unable to do housekeeping tasks or prepare meals. She can take her own medications and use a telephone; however, she cannot bathe independently or climb stairs. The stroke classification score for this patient is number of domains impaired=3; stroke severity=B; functional classification level=lll. AHA.SOC score=3.B.III.
Case 3 is an 85-year-old woman with a right-hemisphere infarct who lives in a skilled-nursing facility. She has paralysis of the left upper and lower extremities, partial hemianopia, cognitive impairment, and depression. She eats independently but is incontinent and needs help with dressing, bathing, toileting, and mobility-related activities. She cannot manage her medications, prepare her meals, use the telephone, or access the community without special transportation arrangements. The stroke classification score for this patient is number of domains impaired=3; stroke severity score=C; functional classification level=V. AHA.SOC score=3.C.V.
New therapies and improved survival after stroke provide an opportune time to develop a stroke outcome classification system that measures the full range of domains affected by stroke. The AHA.SOC score provides a mechanism to comprehensively document stroke impairments and disabilities in a single summary stroke score. The system can be used by healthcare providers to reliably assess recovery, measure responses to treatment, and describe the long-term impact of stroke on survivors.
We thank Sue Min Lai, PhD, for her statistical assistance with this project.
“The American Heart Association Stroke Outcome Classification” was approved by the American Heart Association Science Advisory and Coordinating Committee in December 1997. The full text version is being published simultaneously in Stroke.
A single reprint is available by calling 800-242-8721 (US only) or writing the American Heart Association, Public Information, 7272 Greenville Avenue, Dallas, TX 75231-4596. Ask for reprint No. 71–0144. To purchase additional reprints: up to 999 copies, call 800-611-6083 (US only) or fax 413-665-2671; 1000 or more copies, call 214-706-1466, fax 214-691-6342, or
- Copyright © 1998 by American Heart Association
1998 Heart and Stroke Statistical Update. Dallas, Tex: American Heart Association; 1998.
Gresham GE. Past achievements and new directions in stroke outcome research. Stroke. 1990;21(suppl):II-1-II-2.
Basmajian JV. The call for action. Stroke. 1990;21(suppl):II-3.
International Classification of Impairments, Disabilities, and Handicaps: A Manual of Classification Relating to the Consequences of Disease. Geneva, Switzerland: World Health Organization; 1980.
Nagi S. Disability concepts revisited: implications for prevention. In: Sussman M, ed. Sociology and Rehabilitation. Washington, DC: American Sociological Association; 1965:100–113.
Pope AM, Tarlov AR, eds. Disability in America: Toward a National Agenda for Prevention. Washington, DC: National Academy Press; 1991.
Wood-Dauphinee SL, Williams JI, Shapiro SH. Examining outcome measures in a clinical study of stroke. Stroke.. 1990;21:731–739.
De Haan R, Horn J, Limburg M, Van Der Meulen J, Bossuyt P. A comparison of five stroke scales with measures of disability, handicap, and quality of life. Stroke.. 1993;24:1178–1181.
De Haan R, Aaronson N, Limburg M, Hewer RL, van Crevel H. Measuring quality of life in stroke. Stroke.. 1993;24:320–327.
Dolgin M, ed. Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Great Vessels. 9th ed. Boston, Mass: Little Brown & Co; 1994:253–256.
Gresham GE, Duncan PW, Stason WB, et al. Post-Stroke Rehabilitation. Clinical Practice Guideline, No. 16. Rockville, Md: US Dept of Health and Human Services, Public Health Service, Agency for Health Care Policy and Research; 1995. AHCPR publication 95–0662.
Robinson RG, Starr LB, Kubos KL, Price TR. A two-year longitudinal study of post-stroke mood disorders: findings during the initial evaluation. Stroke.. 1983;5:736–741.
Brott T, Adams HP Jr, Olinger CP, Marler JR, Barsan WG, Biller J, Spilker J, Holleran R, Eberle R, Hertzberg V, Rorick M, Moomaw CJ, Walker M. Measurements of acute cerebral infarction: a clinical examination scale. Stroke.. 1989;20:864–870.
Cote R, Battista RN, Wolfson C, Boucher J, Adam J, Hachinski V. The Canadian Neurological Scale: validation and reliability assessment. Neurology.. 1989;39:638–643.
Kiernan RJ, Mueller J, Langston JW, Van Dyke C. The Neurobehavioral Cognitive Status Examination: a brief but quantitative approach to cognitive assessment. Ann Intern Med.. 1987;107:481–485.
Goodglass H, Kaplan E. Boston Diagnostic Aphasia Examination (BDAE). Philadelphia, Pa: Lea & Febiger; 1983.
Frattali CM, Thompson C, Holland A, Wohl C, Ferketic M. Functional Assessment of Communication Skills for Adults (ASHA/FACS). Rockville, Md: American Speech-Language-Hearing Association; 1995.
Yesavage JA, Brink T, Rose T, Lum O, Huang V, Adey M, Leirer V. Development and validation of a geriatric depression screening scale: a preliminary report. J Psychiatr Res.. 1983;17:37–49.
Radloff LS. The CES-D scale: a self-report depression scale for research in the general population. J Appl Psychol Meas.. 1977;1:385–401.
Mahoney FI, Barthel D. Functional evaluation: the Barthel Index. Md State Med J.. 1965;14:56–61.
Guide for the Uniform Data Set for Medical Rehabilitation (Adult FIM), Version 4.0. Buffalo, NY: State University of New York at Buffalo; 1993.
Lawton MP. Assessing the competence of older people. In: Kent D, Kastenbaum R, Sherwood S, eds. Research Planning and Action for the Elderly. New York, NY: Behavioral Publications; 1972.
Schuling J, de Haan R, Limburg M, Groenier KH. The Frenchay Activities Index: assessment of functional status in stroke patients. Stroke.. 1993;24:1173–1177.