(Stroke. 1995;26:1999-2003.)
© 1995 American Heart Association, Inc.
Articles |
Geographic Variation in Reporting of Stroke Deaths to Underlying or Contributing Causes in the United States
From the Departments of Neurology (D.J.L., P.M.P), Preventive Medicine and Environmental Health (D.J.L.), and Statistics (P.M.P.), and the Sanders Brown Center on Aging (D.J.L.), University of Kentucky Medical Center; and the Neurology Service (D.J.L.), Veterans Affairs Medical Center, Lexington, KY.
Correspondence to Douglas J. Lanska, MD, Department of Neurology, Rm E124, Kentucky Clinic, University of Kentucky, Lexington, KY 40536-0284.
 |
Abstract |
|---|
 Top Abstract IntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
Background and Purpose This study examines the geographic variation in the reporting of deaths with stroke as the underlying or contributing cause in the United States.
Methods Data from the National Center for Health Statistics and Bureau of the Census were used to map the geographic distribution of race- and race/sex-specific, underlying-, contributing-, and multiple-cause age-adjusted stroke mortality rates in the United States by state for 1979 through 1981.
Results Underlying-, contributing-, and multiple-cause age-adjusted stroke mortality rates were significantly clustered for both whites and blacks. However, the spatial distributions of underlying- and contributing-cause rates differed; there was no association between underlying- and contributing-cause rates for either racial group or for the various race/sex groups. There was no association between nonstroke mortality and stroke mortality rates. There was also very little spatial variation and no spatial clustering of the median number of contributing causes reported.
Conclusions The overall large-scale spatial distribution of resident underlying-cause stroke mortality rates cannot be explained by geographic variation in the selection of the underlying cause of death from among all causes reported on the death certificate, by different area-dependent tendencies for mortality generally, or by different tendencies to consider stroke as the cause of death when death occurs. Geographic variation in contributing-cause rates is not explained by variation in tendency to report contributing causes of death.
Key Words: epidemiology • geography • mortality • risk factors
|
Introduction |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
Since at least 1940 there has been a consistent pattern of marked geographic variation in stroke mortality rates within the United States.1 2 3 4 Very high rates are reported in the South—particularly the southeast coastal plain—while very low rates are reported in the Mountain census division and some areas of the Northeast.1 2 3 4 These general patterns of geographic variation have been observed for both sexes and for whites and nonwhites, although stroke rates have been consistently declining in all geographic areas of the continental United States over this interval.1 5 The causes of this marked regional variation remain to be fully elucidated but are probably multifactorial.1 2 4 Some of the observed geographic variation may be due to variations in the distributions of stroke risk factors,1 2 4 the effects of selective migration,1 2 6 and variations in genetic- or host-susceptibility factors.4
Previous studies of geographic variation in stroke mortality within the United States have dealt only with rates based on deaths for which stroke was considered the underlying cause,1 2 4 or they have been undertaken only for restricted geographic areas and restricted population groups.7 8 9 10 11 12 13 14 However, stroke is listed as the underlying cause on the death certificate in only about 60% of deaths in which stroke was considered either the cause or a contributor to death.15 As a result, geographic variation in underlying-cause stroke mortality rates could be biased by geographic variation in underlying cause selection. To assess this and related issues, this study examined the geographic variation in the reporting of deaths with stroke as the underlying or contributing cause in the United States.
|
Subjects and Methods |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
Data on deaths with cerebrovascular disease listed as an underlying or contributing cause of death were obtained from public-use, multiple-cause-of-death, machine-readable, United States mortality data files created by the National Center for Health Statistics (NCHS).16 17 18 Data were tabulated for whites and blacks for the 3-year period centered on the 1980 decennial census year. Stroke deaths were defined as those coded to rubrics 430 through 438 by the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM).19
For contributing-cause tabulations, "record-axis" codes were used: these codes represent the best person-level description of all conditions listed in the medical certification portion of the death certificate. The NCHS derived record-axis codes from the individual conditions reported by using traditional linkage and modification rules for mortality coding; each individual condition ("entity axis") code was examined and modified as appropriate to create a set of record-axis codes that are free of contradictions and duplications and are the most precise within the constraints of the ICD-9-CM and the medical information on the record.20
The racial classification used in the 1980 census differs from the racial classification used for vital statistics data and previous censuses. Racial counts in the 1980 census were particularly affected by changes in reporting practices among the Hispanic population and by changes in the coding and classification of racial groups. In censuses before 1980, virtually all persons of Hispanic origin were considered white; in the 1980 census almost 6.7 million people, most of Hispanic origin, were reported in a residual "other (not specified)" racial category.21 Although vital statistics data do not include the residual racial category, routine 1980 census publications and summary tape files present unmodified data using the racial categories in which the data were collected. Therefore, to maintain comparability, a machine-readable data file of 1980 census data was obtained from the Bureau of the Census in which persons in the residual category were reassigned to three modified racial groups: white, black, and other (including American Indian, Alaskan native, Asian, and Pacific Islander). Details of the reassignment process are given in the technical documentation.21
Modification procedures used with 1980 census data enabled the Bureau of the Census to produce tabulations of state populations that are consistent with racial and Hispanic-origin categories specified by the Office of Management and Budget and used by most federal and state agencies. Overall, modification procedures added 6 340 941 persons (3.4%) to the unmodified white population and 188 389 persons (0.7%) to the unmodified black population. Percentage increases in white and black populations varied significantly by state with the use of modified race data. For whites, the percentage increase varied from 0.1% to 19.1%, with New Mexico (19.1%), California (12.7%), Texas (10.2%), Arizona (10.0%), Colorado (6.4%), and New York (5.4%) showing the greatest increases. For blacks, the percentage increase varied from 0.1% to 12.9%, with Rhode Island (12.9%) and Massachusetts (8.2%) showing the largest increases.
Age-, race-, sex-, and state-specific rates were calculated separately for deaths for which cerebrovascular disease was listed as the underlying cause or a contributing cause of death on the death certificate. Average annual age-adjusted stroke mortality rates (per 100 000 population) by race and race/sex group were computed by the direct method, that is, by applying the age-specific death rates for stroke to the standard population distributed by age. The reference population used was the total US population enumerated on April 1, 1980. Separate choropleth22 maps were generated to display the geographic variation of age-adjusted, underlying-, contributing-, and multiple-cause stroke mortality rates at a state level by race and by race/sex group. Multiple-cause rates include deaths in which stroke was listed as either the underlying cause or a contributing cause.
Spatial autocorrelation of age-adjusted rates was assessed using Moran's I spatial autocorrelation coefficient.23 24 25 The expected value of I for a random arrangement is of small magnitude and negative; positive values of I imply clustering, whereas extreme negative values imply dispersion. The range of possible values of I depends on the spatial structure of a particular study region. Significance testing was performed under the randomization hypothesis.25 Given the specific observed values of age-adjusted mortality rates, the probability that they could have been arranged in the observed way by chance is determined by calculating a standard normal deviate from the calculated value, the expected value, and the standard deviation.
|
Results |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
The graphs for whites illustrate intense clustering of underlying- (Fig 1
; I=0.575,
P<<.0001), contributing- (Fig 2); I=0.536,
P<<.0001), and multiple-cause (Fig 3; I=0.555, P<<.0001)
age-adjusted stroke mortality rates in the United States. For
underlying-cause rates, high-rate states were concentrated in
the South, and low-rate states were concentrated in the Mountain
census division and along the northern Atlantic coast. For
contributing-cause rates, the highest underlying- and
multiple-cause mortality rates occurred almost exclusively east of
the Mississippi River without an evident north-south gradient. The
distribution of multiple-cause rates was intermediate between the
distributions of underlying- and contributing-cause rates. State
underlying- and contributing-cause rates were not significantly
associated for whites (r=.26, P=.07).
|
|
|
The graphs for blacks are more sparse because of small population sizes for many of the states. Nevertheless, the graphs for blacks also show statistically significant clustering of underlying- (I=0.610, P<<.0001), contributing- (I=0.208, P=.04), and multiple-cause (I=0.454, P<.0001) age-adjusted stroke mortality rates. The highest underlying- and multiple-cause rates were strongly clustered in the Southeast, especially involving states in the south Atlantic and East South Central census divisions. The highest contributing-cause rates were more scattered but were generally most concentrated in the east north central and south Atlantic states. Mortality rate maps for blacks are not shown but are available from the National Auxiliary Publication Service (see "Acknowledgments"). State underlying- and contributing-cause rates were not associated for blacks (r=-.06, P=.75).
For each race/sex group, the distribution of underlying-, contributing-, and multiple-cause rates was very close to that of the racial group of which it was a part. Mortality rate maps by race/sex group are not shown but are available from the National Auxiliary Publication Service (see "Acknowledgments"). State underlying- and contributing-cause rates were not associated for white females (r=.11, P=.44), black males (r=.02, P=.90), or black females (r=-.22, P=.26), but there was a modest association for white males (r=.46, P=.001).
Geographic variation in reported underlying-cause stroke mortality rates is not explained by different area-dependent tendencies for mortality generally, nor can variations in stroke rates be explained by different tendencies to consider stroke as the cause of death. State age-adjusted nonstroke mortality rates (ie, rates based on deaths with underlying and contributing causes other than stroke) and age-adjusted underlying-cause stroke mortality rates were not associated for all whites (r=.27, P=.06), for white females (r=.08, P=.57), for all blacks (r=.06, P=.72), for black males (r=.08, P=.68), or for black females (r=-.05, P=.81). There was a modest positive association for white males (r=.41, P=.003).
Geographic variation in contributing-cause rates is not explained by variation in tendency to report contributing causes of death. For whites, the median number of contributing causes reported for deaths with stroke was extremely homogeneous for all states (one for Alabama and Arkansas and two for all other states), and there was no spatial autocorrelation (I=-0.053, P=.65). While there was more heterogeneity in the median number of contributing causes reported by state for blacks (range, 1 to 4), there was no significant spatial clustering (I=0.074, P=.28). A table of the median number of contributing causes by race, sex, and state is not shown but is available from the National Auxiliary Publication Service (see "Acknowledgments").
|
Discussion |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
The nonrandom distribution of stroke mortality across the United States; persistence of the pattern over more than five decades; similarity of the pattern for different age, race, and sex groups; the fact that the pattern is not delimited by county, state, or other political administrative boundaries; and the extreme magnitude of the differences between rates in high- and low-rate areas suggest that the geographic pattern of stroke mortality rates is not an artifact of different diagnostic and reporting practices.1 5 In addition, the large regional differences in stroke mortality parallel geographic differences in stroke incidence26 and in hospital utilization rates for stroke.2 27
The present results demonstrate that the large-scale geographic patterns of underlying-cause, resident-state stroke mortality rates in the United States are not explained by differential selection of the underlying cause of death from among all causes reported, by different area-dependent tendencies for mortality generally, or by different tendencies to consider stroke as the cause of death when death occurs. If high rates were due to preferential selection of stroke as the underlying cause of death from among all causes reported on the death certificate, one would anticipate a negative association between underlying- and contributing-cause rates; instead, there was no association for either whites or blacks or for any race/sex group except white males, for which there was a modest positive association. Also, if the geographic pattern of stroke mortality simply reflected an area-dependent tendency to die from any cause, there should have been a positive association between stroke and nonstroke mortality rates, but there was no association. Furthermore, if the geographic pattern of stroke mortality was due to an area-dependent tendency to attribute deaths to stroke, there should have been a negative association between stroke and nonstroke mortality rates, but again there was no association.
Previous analyses of variation in underlying-cause selection have been undertaken only for restricted geographic areas and restricted population groups.7 8 9 10 11 12 13 14 In 1969, Kuller and colleagues7 8 9 10 reported the results of the Nationwide Cerebrovascular Disease Mortality Study, which analyzed a systematic sample of death certificates and hospital records for 6314 whites aged 45 to 69 years who died during 1965 in one of the nine state economic areas studied. The study areas were selected to include a range of stroke mortality rates for white men aged 35 to 74 years. Although overall age-adjusted stroke mortality rates in high-rate areas were more than twice those in low-rate areas, there was relatively little difference in the proportion of death certificates listing stroke as the underlying cause of death among all certificates listing stroke as either an underlying or contributing cause of death (62% in the low-rate areas studied versus 69% in the high-rate areas). Variations in mortality rates also could not be explained by differences in the frequency that clinical stroke diagnoses were listed on death certificates or differences in the accuracy of stroke diagnoses.
In 1973, Nefzger, Acheson, and Heyman11 12 13 14 reported the results of a study of stroke mortality among US veterans in Georgia and five western states (Colorado, Idaho, Montana, Utah, and Wyoming) who died during a 1-year interval from July 1, 1967, through June 30, 1968. Mortality and morbidity data were obtained from death certificates and clinical records during the last year of life. As expected, stroke mortality rates were significantly higher in Georgia than in the western states. These differences in mortality rates could not be explained by differences in choice of underlying cause of death when multiple causes contributed to death, the frequency with which clinical stroke diagnoses were listed on death certificates, differences in the accuracy of stroke diagnoses, variations in standards of medical care, or variations in rates of death from all causes.
Nonartifactual variations in stroke mortality rates may theoretically arise from differences in stroke incidence, survival after stroke, or both.28 29 30 The geographic distribution of hospital usage for stroke follows closely the distribution of reported stroke mortality rates.1 27 In contrast, case-fatality rates show relatively little interstate variation, are not similarly clustered, and are much less strongly associated with stroke mortality rates.1 Together, this information suggests that factors determining stroke occurrence and hospital utilization are more important than factors determining case fatality in explaining the long-standing geographic distribution of stroke mortality in the United States.1 Factors affecting only case fatality but not hospital utilization, such as the quality of medical care provided in the hospital, cannot explain the geographic distribution of stroke mortality in the United States.1
Regional variation in stroke risk factors (eg, prevalence of hypertension, diabetes, and cigarette smoking) has been documented by various US government health surveys, but none of the factors have been clearly related to the pattern of geographic variation in stroke morbidity and mortality.1 4 Systematic attempts to investigate the geographic variation in stroke risk factors as an explanation of the geographic variation in stroke frequency have been few and the results inconsistent.1 4 31 32 33 34 35 Recognized stroke risk factors, including hypertension, apparently account for only a small fraction of the spatial variation in stroke mortality.1 4 35 Certainly, the spatial distributions of stroke risk factors, and the spatial distributions of nonstroke mortality associated with the risk factors, do not closely correlate with the spatial distribution of stroke mortality.2 In addition, the magnitude of the interregional variation in recognized stroke risk factor prevalence as determined from national health surveys is probably insufficient to explain the marked and persistent variation in stroke mortality.2 Furthermore, in many cases the geographic variation in stroke risk factor prevalence has not been consistent across studies or among the different race/sex groups.2
Another factor that may explain at least some of the spatial variation
in stroke mortality rates is selective migration. Although the overall
large-scale spatial distribution of resident stroke mortality rates
cannot be explained by migration effects,6 some individual
states have rates that are strongly influenced by
migration.1 2 6 In particular, interstate migration
by the elderly strongly influences both stroke hospital admission rates
and mortality from stroke in certain Sunbelt retirement destination
states, especially Florida.1 2 6 For more than four
decades, Florida has been the leading destination of elderly interstate
migrants, receiving up to a quarter of all elderly migrants:
in-migrants to Florida make up a phenomenally high proportion
(approximately 88%) of the resident elderly population of that state,
with recent in-migrants (within the previous 5 years) accounting
for about 20% of the elderly population. These in-migrants are
almost exclusively white, and a large majority are healthy,
independent, well educated, and financially secure. As a result of the
selective in-migration of large numbers of healthy elderly whites,
stroke mortality rates for white residents of Florida became
significantly lower than the national rate after World War II and have
remained low (see Fig 1
) in contrast to persistently significantly high
rates among black residents of Florida and in contrast to persistently
high rates among both whites and blacks in other south Atlantic states
over this period.1 6 This migration-induced selection
by health status also produced lower-than-expected stroke
hospitalization rates in Florida but not in other south Atlantic
states.1
Since artifactual explanations, known stroke risk factors, and migration effects seem unlikely to account for the large-scale geographic variation in stroke mortality within the United States, further study will be needed to elucidate and better understand the various factors responsible.
|
Acknowledgments |
|---|
This project was supported in part by a clinical investigator development award from the National Institutes of Health (K08-NS01549, Dr Lanska), by research advisory group funding from the Office of Research and Development of the Department of Veterans Affairs (Dr Lanska), and by the philanthropic support of Jayne Bolotin (Dr Lanska). See National Auxiliary Publications Service document 05242 for 25 pages of supplementary material. Order from NAPS c/o Microfiche Publications, PO Box 3513, Grand Central Station, New York, NY 10163-3513. Remit in advance, in US funds only, $9.25 for photocopies or $4 for microfiche. Outside the United States or Canada, add postage of $4.50 for the first 20 pages and $1 for each 10 pages of material thereafter. The postage charge for any microfiche order is $1.75 for the first microfiche and $.50 for each fiche thereafter.
Received May 24, 1995; revision received August 3, 1995; accepted August 3, 1995.
|
References |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
-
Lanska DJ. Geographic distribution of
stroke mortality in the United States: 1939-41 to 1979-81.
Neurology. 1993;43:1839-1851.
[Abstract/Free Full Text] -
Lanska DJ, Kryscio R. The geographic
distribution of hospital admissions, case fatality, and mortality from
stroke among Medicare enrollees. Neurology. 1994;44:1541-1550.
[Abstract/Free Full Text] -
Lanska DJ, Mi X. Decline in US stroke mortality
in the era before antihypertensive therapy. Stroke. 1993;24:1382-1388.
[Abstract/Free Full Text] -
Lanska DJ, Kuller L. The geography of stroke
mortality in the United States and the concept of a stroke
belt. Stroke. 1995;26:1145-1149.
[Free Full Text] -
Lanska DJ, Peterson PM. Geographic variation in
the decline of stroke mortality in the United States.
Stroke. 1995;26:1159-1165.
[Abstract/Free Full Text] -
Lanska DJ, Peterson PM. Effects of interstate
migration on the geographic distribution of stroke mortality in the
United States. Stroke. 1995;26:554-561.
[Abstract/Free Full Text] -
Kuller LH, Bolker A, Saslaw MS, Paegel BL, Sisk C,
Borhani N, Wray JA, Anderson H, Peterson D, Winkelstein W Jr, Cassel J,
Spiers P, Robinson AG, Curry H, Lilienfeld AM, Seltser R.
Nationwide cerebrovascular disease mortality study, I: methods and
analysis of death certificates. Am J
Epidemiol. 1969;90:536-544.
[Abstract/Free Full Text] -
Kuller LH, Bolker A, Saslaw MS, Paegel BL, Sisk C,
Borhani N, Wray JA, Anderson H, Peterson D, Winkelstein W Jr, Cassel J,
Spiers P, Robinson AG, Curry H, Lilienfeld AM, Seltser R.
Nationwide cerebrovascular disease mortality study, II: comparison of
clinical records and death certificates. Am J
Epidemiol. 1969;90:545-555.
[Abstract/Free Full Text] -
Kuller LH, Bolker A, Saslaw MS, Paegel BL, Sisk C,
Borhani N, Wray JA, Anderson H, Peterson D, Winkelstein W Jr, Cassel J,
Spiers P, Robinson AG, Curry H, Lilienfeld AM, Seltser R.
Nationwide cerebrovascular disease mortality study, III: accuracy of
the clinical diagnosis of cerebrovascular disease. Am J
Epidemiol. 1969;90:556-566.
[Abstract/Free Full Text] -
Kuller LH, Bolker A, Saslaw MS, Paegel BL, Sisk C,
Borhani N, Wray JA, Anderson H, Peterson D, Winkelstein W Jr, Cassel J,
Spiers P, Robinson AG, Curry H, Lilienfeld AM, Seltser R.
Nationwide cerebrovascular disease mortality study, IV: comparison of
the different clinical types of cerebrovascular disease.
Am J Epidemiol. 1969;90:567-578.
[Abstract/Free Full Text] - Nefzger MD, Acheson RM, Heyman A. Mortality from stroke among U.S. veterans in Georgia and 5 western states, I: study plan and death rates. J Chronic Dis. 1973;26:393-404. [Medline] [Order article via Infotrieve]
- Acheson RM, Nefzger MD, Heyman A. Mortality from stroke among U.S. veterans in Georgia and 5 western states, II: quality of death certification and clinical records. J Chronic Dis. 1973;26:405-415. [Medline] [Order article via Infotrieve]
- Acheson RM, Heyman A, Nefzger MD. Mortality from stroke among U.S. veterans in Georgia and 5 western states, III: hypertension and demographic characteristics. J Chronic Dis. 1973;26:417-429. [Medline] [Order article via Infotrieve]
- Heyman A, Nefzger MD, Acheson RM. Mortality from stroke among U.S. veterans in Georgia and 5 western states, IV: clinical observations. J Chronic Dis. 1973;26:431-446. [Medline] [Order article via Infotrieve]
- National Center for Health Statistics. Vital Statistics Mortality Data, Multiple Cause Detail for ICD-9 1980 Data [tape contents and documentation package]. Springfield, Va: National Technical Information Service; 1983.
- National Center for Health Statistics. Vital Statistics, Mortality, Multiple Cause-Of-Death, Detail, 1979 [machine-readable data file]. Springfield, Va: National Technical Information Service; 1982.
- National Center for Health Statistics. Vital Statistics, Mortality, Multiple Cause-Of-Death, Detail, 1980 [machine-readable data file]. Springfield, Va: National Technical Information Service; 1983.
- National Center for Health Statistics. Vital Statistics, Mortality, Multiple Cause-Of-Death, Detail, 1981 [machine-readable data file]. Springfield, Va: National Technical Information Service; 1984.
- US Dept of Health and Human Services. The International Classification of Diseases, 9th revision, Clinical Modification: ICD-9-CM, Vol 1. 3rd ed. Washington, DC: US Government Printing Office; 1989. US Dept of Health and Human Services publication PHS 89-1260.
- National Center for Health Statistics. Vital Statistics Mortality Data: Multiple Cause-of-Death, Detail, 1979 [tape contents and documentation package]. Springfield, Va: National Technical Information Service; 1982.
- Bureau of the Census. Census of Population and Housing, 1980: County Population by Age, Sex, Race, and Spanish Origin (Preliminary OMB-Consistent Modified Race) [tape technical documentation]. Washington, DC: US Bureau of the Census; 1983.
- Dent BD. Cartography: Thematic Map Design. 2nd ed. Dubuque, Iowa: William C. Brown Publishers; 1990:145-182.
-
Moran PAP. Notes on continuous stochastic
phenomena. Biometrika. 1950;37:17-23.
[Free Full Text] - Cliff AD, Ord JK. Spatial Processes: Models and Applications. London, UK: Pion Limited; 1981.
- Ebdon D. Statistics in Geography. 2nd ed. New York, NY: Basil Blackwell Inc; 1985.
-
Kuller L, Anderson H, Peterson D, Cassel J.
Nationwide cerebrovascular disease morbidity study.
Stroke. 1970;1:86-98.
[Abstract/Free Full Text] - Centers for Disease Control. Cerebrovascular disease mortality and Medicare hospitalization—United States, 1980-1990. JAMA. 1992;268:858-859. [Medline] [Order article via Infotrieve]
-
Morrison AS. Sequential pathogenic components of
rates. Am J Epidemiol. 1979;109:709-718.
[Abstract/Free Full Text] - Lilienfeld AM, Lilienfeld DE. Foundations of Epidemiology. 2nd ed. New York, NY: Oxford University Press; 1980.
- Kleinbaum DG, Kupper LL, Morgenstern H. Epidemiologic Research: Principles and Quantitative Methods. New York, NY: Lifetime Learning Publications; 1982:124-130.
- Nefzger MD, Kuller LH, Lilienfeld AM, Diamond EL, Miller GD, Stolley PD, Tonascia S. Three-area epidemiologic study of geographic differences in stroke mortality, I: background and methods. Stroke. 1977;8:547-550.
-
Stolley PD, Kuller LH, Nefzger MD, Tonascia S,
Lilienfeld AM, Miller GD, Diamond EL. Three-area
epidemiological study of geographic differences in stroke mortality,
II: results. Stroke. 1977;8:551-557.
[Abstract/Free Full Text] - Rocella EJ, Lenfant C. Regional and racial differences among stroke victims in the United States. Clin Cardiol. 1989;12:IV-18-IV-22.
- Perry HM Jr, Gillespie KN, Romeis JC, Smith MM, Virgo KS, Carmody SE, Sambhi MP. Effects of `stroke-belt' residence, screening blood pressure and personal history risk factors on all-cause mortality among hypertensive veterans. J Hypertens. 1994;12:315-321. [Medline] [Order article via Infotrieve]
- Kovar MG, Pokras R, Collins JG. Trends in medical care and survival from stroke. Ann Epidemiol. 1993;3:466-470.[Medline] [Order article via Infotrieve]
This article has been cited by other articles:
 |
|
 |
|
  D. T. Lackland, D. L. Bachman, T. D. Carter, D. L. Barker, S. Timms, and H. Kohli The Geographic Variation in Stroke Incidence in Two Areas of the Southeastern Stroke Belt : The Anderson and Pee Dee Stroke Study Stroke, October 1, 1998; 29(10): 2061 - 2068. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. W. Pickle, M. Mungiole, and R. F. Gillum Geographic Variation in Stroke Mortality in Blacks and Whites in the United States Stroke, August 1, 1997; 28(8): 1639 - 1647. [Abstract] [Full Text]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||