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NHLBI Workshop

Data Needs for Cardiovascular Events, Management, and Outcomes

Stroke

May 26-27, 2005
Virginia J. Howard
University of Alabama at Birmingham


Stroke is the third leading cause of death in the United States and one of the leading causes of long-term disability. It is estimated that 700,000 Americans experience a new or new recurrent stroke each year, 500,000 first strokes, and 200,000 recurrent strokes.  It is estimated that in 2002, there were 5.4 million stroke survivors (i.e., prevalence of previous stroke). The Framingham study has shown that 15-30% of stroke survivors are permanently disabled. 1  In addition to these “clinically diagnosed” strokes, MRI and CT data from the Cardiovascular Health Study and the Atherosclerosis Risk in Communities Study suggest that  there may be as many as 13 million “silent strokes” without diagnosed clinical symptoms but with radiologic  evidence of infarction.1 The presence of these “silent strokes” is likely associated with clinically important but less identifiable symptoms including decreased cognitive functioning; the odds of having a clinically pronounced stroke has been estimated to be over three times greater among those with silent infarctions.2 

Although declines in stroke mortality rates have occurred, approximately a 60% decline since the 1960’s, the public health burden of stroke remains high.  With the “graying of America” it is anticipated that the absolute number of strokes will more than double in the next 40 years.3  In addition, health disparities, including a substantial excess (RR of 3 to 4 at ages 55-65) among African Americans and geographic disparities (i.e., the “Stroke Belt”), have persisted in the face of the overall declining mortality.

For 2005, the estimated direct and indirect cost of stroke is $56.8 billion. This figure includes health expenditures such as costs of physicians, hospital and nursing home services and lost productivity, but is likely an underestimate because it may not include informal care costs and costs of comorbidities.1,4    

Guidelines for the prevention and management of first and recurrent stroke and rehabilitation have been developed and are updated periodically. 5-12  Programs such as the Joint Commission on Accreditation of Healthcare Organizations (JCAHO), the American Stroke Association’s Get With the Guidelines-Stroke (GWTG-Stroke) and recommendations from the Brain Attack Coalition are focused on improving stroke care.13-15 There are no representative data available at the national level to monitor medical practice patterns, quality of care and patient outcomes, according to these guidelines, however, the Centers for Medicare and Medicaid Services (CMS) collects data on several secondary prevention measures among hospitalized Medicare beneficiaries.  The National Committee for Quality Assurance (NCQA) reports data from participating managed care organizations, but this is a voluntary system and not nationally representative. Most recently, the Paul Coverdell National Acute Stroke Registry was initiated to collect data on and track the quality of acute stroke care.16  

Existing surveillance systems and cohort studies that collect these data include:

1.  Community-based surveillance studies

  • Greater Cincinnati/Northern Kentucky Stroke Study (GCNKSS)17
  • Brain Attack Surveillance in Corpus Christi (BASIC) Project18
  • Atherosclerosis Risk in Communities – Surveillance Systems (ARIC)19

2.  Hospital-based surveillance studies

  • Paul Coverdell National Acute Stroke Registry16
  • Rochester Minnesota Epidemiologic Program20

3.  Cohort studies

  • Framingham21
  • Atherosclerosis Risk in Communities – Cohort (ARIC)19
  • Cardiovascular Health Study (CHS)22
  • Multi-Ethnic Study of Atherosclerosis (MESA)23
  • REasons for Geographic And Racial Differences in Stroke (REGARDS)24

The community-based programs have the substantial strength of providing the most unbiased estimates of incidence (including non-hospitalized stroke, etc), but have the major shortcoming of being based in specific communities hence failing to reflect the substantial geographic variations in stroke mortality.  The hospital-based programs have the advantage of access to hospital data to quantify stroke subtype and severity, but require hospitalization for the stroke in order to detect events; these are also limited to specific communities.  The cohort studies have the advantage of assessment of risk factors prior to the event and providing a clearly defined cohort to identify events (i.e., clearly defined denominator for event rates), but will provide less-precise estimates of incidence as a result of limitations of sample size. Stroke mortality rates vary across race-ethnicity and geographic regions and many of these studies do not include all race-ethnic groups, and those that do are limited in sample size, especially in younger ages.

Gaps in present knowledge:

  1. Much of what we know about the burden of stroke is from stroke mortality rather than stroke incidence, with little data on incidence. 
  2. Mortality data do not traditionally (and reliably) capture data on stroke subtypes.  The major subtypes are remarkably different diseases, also placing different burdens on the public health.
  3. With few exceptions (Rochester Minnesota Epidemiologic Project Twin Cities of Minneapolis, and most recently, the Greater Cincinnati/Northern Kentucky Stroke Study and Corpus Christi), there is a lack of data on incidence, case-fatality and trends over time.
  4. There are even less incidence and case fatality data on important, but relatively rare, stroke subtypes – specifically, subarachnoid hemorrhage and intracerebral hemorrhage.   
  5. National, representative data on compliance with prevention and treatment guidelines are not yet available.

References

  1. American Heart Association.  Heart Disease and Stroke Statistics – 2005 Update. Dallas, Texas:  American Heart Association; 2005.
  2. Wong TY, Klein R, Sharrett AR, Couper DJ, Klein BE, Liao DP, Hubbard LD, Mosley TH. Atherosclerosis Risk in Communities Study. Cerebral white matter lesions, retinopathy, and incident clinical stroke. JAMA 2002;288:67-74.
  3. Howard G, Howard VJ.  Stroke incidence, mortality and prevalence.  In:  Gorelick PB and Alter M., eds. Stroke Prevention.  Parthenon Publishing, 2002.
  4. Evers SMAA, Struijs JN, Ament AJHA, van Genugten MLL, Jager JHC, van den Bos GAM.  International comparisons of stroke cost studies.  Stroke 2004;35:1209-1215.
  5. Goldstein LB, Adams R, Becker K, Furberg CD, Gorelick PB, Hademenos G, Hill M, Howard G, Howard VJ, Jacobs B, Levine SR, Mosca L, Sacco RL, Sherman DG, Wolf PA, del Zoppo, GJ. Primary prevention of ischemic stroke: A statement for healthcare professionals from the Stroke Council of the American Heart Association.  Stroke 2001;32:280-299.
  6. Straus SE, Majumdar SR, McAlister FA.  New evidence for stroke prevention:  scientific review.  JAMA 2002;288:1388-1395.
  7. Wolf PA, Clagett GP, Eaton JD, Goldstein LB, Gorelick PB, Kelly-Hayes M, Sacco RL, Whisnant JP.  Preventing ischemic stroke in patients with prior stroke and transient ischemic attack.  A statement for healthcare professionals from the Stroke Council of the American Heart Association.  Stroke 1999;30:1991-1994.
  8. Gorelick PB, Sacco RL, Smith DB, Alberts M, Mustone-Alexaner L, Rader D, Ross JL, Raps E, Ozer MN, Brass LM, Malone ME, Goldberg S, Booss J, Hanley DF, Toole JF, Greengold NL, Rhew DC. Prevention of a first stroke:  A review of guidelines and a multidisciplinary consensus statement from the National Stroke Association.  JAMA 1999;281:1112-1120.
  9. Biller J, Feinberg WM, Castaldo JE et al.  Guidelines for carotid endarterectomy:  a statement for healthcare professionals from a Special Writing Group of the Stroke Council, American Heart Association.  Circulation 1998;97:501-509.
  10. Department of Veterans Affairs and Department of Defense.  VA/DoD Clinical Practice Guideline for the Management of Stroke Rehabilitation.  Washington, D.C: Department of Veterans Affairs and Department of Defense, 2003.
  11. Mayberg MR, Batjer HH, Dacey R, et al.  Guidelines for the management of aneurismal subarachnoid hemorrhage:  A statement for healthcare professionals from a special writing group of the Stroke Council, American Heart Association.  Circulation 1994;90:2592-2605.
  12. Schwamm LH, Pancioli A, Acker III JE, Goldstein LB, Zorowitz RD, Shephard TJ, Moyer P, Gorman M, Johnston SC, Duncan PW, Gorelick P, Frank J, Stranne SK, Smith R, Federspiel W, Horton KB, Magnis E, Adams RJ. Recommendations for the establishment of stroke systems of care:  Recommendations from the American Stroke Association’s Task Force on the Development of Stroke Systems.  Stroke 2005;36:690-703.
  13.  Holloway RG, Vickery BG, Benesch C, Hinchey JA, Bieber J. National Expert Panel.  Development of performance measures of acute ischemic stroke.  Stroke 2001;32:2058-2074.
  14. Joint Commission on Accreditation of Healthcare Organizations (JCAHO).  Primary Stroke Center Certification Program.  Available at:  http://www.strokeassociation.org/presenter.jhtml?identifier=3016808.
  15. American Stroke Association.  Get with the guidelines—stroke.  Available at:  www.strokeassociation.org/presenter.jhtml?identifier=3002728.  Accessed May 25, 2005.
  16. The Paul Coverdell Prototype Registries Writing Group.  Acute stroke care in the US:  Results from 4 pilot prototypes of the Paul Coverdell National Acute Stroke Registry.  Stroke 2005;36:1232-1240.
  17. Broderick J, Brott T, Kothari R, Miller R, Khoury J, Pancioli A, Gebel J, Mills D, Minneci L, Shukla R: The Greater Cincinnati/Northern Kentucky Stroke Study : Preliminary first-ever and total incidence rates of stroke among blacks. Stroke 1998;29:415-421.
  18. Smith MA, Risser JM, Moye LA, Garcia N, Akiwumi O, Uchino K, Morgenstern LB. Designing multi-ethnic stroke studies: the Brain Attack Surveillance in Corpus Christi (BASIC) project. Eth Dis 2004:14:520-526.
  19. Anonymous. The Atherosclerosis Risk in Communities (ARIC) Study: design and objectives. Am J Epid 1989;129:687-702
  20. Leibson CL, Ballard DJ, Whisnant JP, Melton LJ 3rd. The compression of morbidity hypothesis: promise and pitfalls of using record-linked data bases to assess secular trends in morbidity and mortality. Milbank Quarterly 1992;70:127-154
  21. Higgins MW. The Framingham Heart Study: review of epidemiological design and data, limitations and prospects.  Prog Clin Biologic Res 1984;147:51-64
  22. Fried LP, Borhani NO, Enright P, Furberg CD, Gardin JM, Kronmal RA, Kuller LH, Manolio TA, Mittelmark MB. Newman A. et al. The Cardiovascular Health Study: design and rationale. Ann Epid 1991:1:263-276, 1991
  23. Bild DE, Bluemke DA, Burke GL, Detrano R, Diez Roux AV, Folsom AR, Greenland P, Jacobs Jr. DR, Kronmal R, Liu K, Nelson JC, O’Leary D, Saas MF, Shea, Szklo M, Tracy RP.  Multi-Ethnic Study of Atherosclerosis:  objectives and design.  Am J Epidemiol 2002;156:871-881.
  24. Howard VJ, Cushman M, Pulley L, Gomez C, Go R, Prineas RJ, Graham A, Moy CS, Howard G.  The Reasons for Geographic And Racial Differences in Stroke (REGARDS) Study:  Objectives and Design. Neuroepidemiology 2005: in press.

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