Original Paper Neuroepidemiology 2005;25:135–143 Published online: June 29, 2005 DOI: 10.1159/000086678 The Reasons for Geographic and Racial Differences in Stroke Study: Objectives and Design Virginia J. Howard a Mary Cushman c LeaVonne Pulley d Camilo R. Gomez e Rodney C. Go a Ronald J. Prineas f Andra Graham g Claudia S. Moy h George Howardb a b Departments of Epidemiology and Biostatistics, University of Alabama at Birmingham, c Birmingham, Ala., Departments of Medicine and Pathology, Laboratory for Clinical Biochemistry Research, d University of Vermont, Burlington, Vt. , Department of Health Behavior, University of Arkansas Health Science e f University, Little Rock, Ark. , Alabama Neurological Institute, Birmingham, Ala. , Department of Public Health g Sciences, Wake Forest University School of Medicine, Winston-Salem, N.C. , Examination Management h Services, Incorporated, Dallas, Tex. , and National Institute of Neurological Disorders and Stroke, Rockville, Md. , USA Key Words study allow for the creation of a national cohort to ad- Cerebrovascular disorders, epidemiology Cohort dress geographic and ethnic differences in stroke. studies Epidemiologic methods African-Americans Copyright © 2005 S. Karger AG, Basel Risk factors Geography Southeastern United States Prospective studies The ‘Stroke Belt’ was fi rst identifi ed in 1965 as a region of high stroke mortality in the Southeastern US [1] , and Abstract it is frequently defi ned as including 8 southern states: The REasons for Geographic And Racial Differences in North Carolina, South Carolina, Georgia, Tennessee, Stroke (REGARDS) Study is a national, population-based, Mississippi, Alabama, Louisiana, and Arkansas. Excess longitudinal study of 30,000 African-American and white stroke mortality rates in this region have been document- adults aged 645 years. The objective is to determine the ed since at least 1940 [2] and despite minor geographic causes for the excess stroke mortality in the Southeast- shifts [3] , they still persist [4, 5] . Within the Stroke Belt, ern US and among African-Americans. Participants are a ‘Buckle’ region along the coastal plain of North Caro- randomly sampled with recruitment by mail then tele- lina, South Carolina, and Georgia has been identifi ed phone, where data on stroke risk factors, sociodemo- with even a higher stroke mortality rate than the remain- graphic, lifestyle, and psychosocial characteristics are der of the Stroke Belt ( fi g. 1 ) [6] . collected. Written informed consent, physical and phys- Two recent reviews identifi ed at least 10 published iological measures, and fasting samples are collected hypotheses of the causes of the Stroke Belt [5, 7] . These during a subsequent in-home visit. Participants are fol- hypotheses include an array of potential causes as diver- lowed via telephone at 6-month intervals for identifi ca- gent as differences in socioeconomic status, quality of tion of stroke events. The novel aspects of the REGARDS health care, lifestyle choices (including diet), and differ- © 2005 S. Karger AG, Basel Virginia J. Howard, Department of Epidemiology School of Public Health, Ryals Building, Room 210F Fax +41 61 306 12 34 University of Alabama at Birmingham, 1665 University Blvd. E-Mail [email protected] Accessible online at: Birmingham, AL 35294-0022 (USA) www.karger.com www.karger.com/ned Tel. +1 205 934 7197, Fax +1 205 934 8665, E-Mail [email protected] Downloaded by: University of Alabama, Lister Hill Library 138.26.188.92 - 1/14/2015 6:20:31 PM Region: Stroke Belt Stroke Buckle Remainder of US Fig. 1. Map of US counties showing regions in the REGARDS study. ences in major cardiovascular risk factors, including hy- African-Americans, primarily in the population below pertension [7] . Despite the potential public health impact age 65, with no excess seen in the oldest age group [9] . of the Stroke Belt, few data are available addressing these While that study has provided important insights into hypotheses, and it is not even known whether regional racial differences in stroke incidence, it is limited to a differences in stroke incidence contribute to this excess single geographic region. stroke mortality. There are even fewer data available addressing racial In addition, overall stroke mortality rates among Af- differences in the role of stroke risk factors. The exception rican-Americans are about 50% higher than whites with is the National Health and Nutrition Examination Sur- the largest disparity at younger ages [8, 9] . Like the excess vey (NHANES), and while it is not optimally designed to stroke mortality in the Southeast, little is known about describe geographic variations in stroke risk factors, it has the causes underlying the excess stroke mortality in provided key national data on prevalence of risk factors blacks. by ethnic group [12] . NHANES focuses on a broad spec- Most large population-based epidemiological studies trum of diseases, and therefore does not describe all stroke have been conducted in predominantly white communi- risk factors. ties (e.g. Framingham, Mass., and Rochester, Minn., Based on very limited data, the excess stroke mortal- USA) [10, 11] . As a result, little is known about stroke ity in African-Americans may be attributed in part to a incidence among African-Americans. The exception to higher incidence rate. Gillum, on behalf of the Centers this is the Greater Cincinnati/Northern Kentucky Stroke for Disease Control, recently proposed recommendations Study (GCNKSS), which is estimating stroke incidence for population-based research on stroke mortality in Af- in a racially mixed community [9] . Early results from that rican-Americans [13] . Among these recommendations is study suggest a substantial excess incidence of stroke in a call for the use of various study designs ‘to assess the 136 Neuroepidemiology 2005;25:135–143 Howard/Cushman/Pulley/Gomez/Go/ Prineas/Graham/Moy/Howard Downloaded by: University of Alabama, Lister Hill Library 138.26.188.92 - 1/14/2015 6:20:31 PM role of racial differences in stroke subtype distribution, scientifi c leadership of the study. Study methods were reviewed and incidence, case fatality, recurrence, competing mortality, approved by all involved institutional review boards, as well as an utilization of therapeutic stroke care, population preva- external observational study monitoring board appointed by the funding agency. lence of stroke and heart disease, hypertension control, and diabetes prevalence on the excess mortality in blacks, Sampling, Recruitment, and Initial Telephone Interview the slowdown in the decline of mortality rates, and the The REGARDS sample is selected from a commercially avail- geographic variation in stroke’ [13] . This recommenda- able nationwide list purchased through Genesys Inc., stratifi ed to tion addresses almost all aspects of the epidemiology of refl ect the specifi c age-race-sex-geographic strata described below. Sample listings are purchased in batches of 50,000 households to racial/ethnic differences in stroke. ensure the most current telephone numbers and addresses. Criteria The REasons for Geographic And Racial Differences for inclusion in the sample include having a name, telephone num- in Stroke (REGARDS) study was designed to elucidate ber and address in the Genesys database. The recruitment goal of factors underlying the excess stroke mortality in the 30,000 participants includes 30% from the Stroke Belt, 20% from the Stroke Buckle, and the remainder from elsewhere in the conti- Southeastern US and among African-Americans. Here, nental U.S. Within each region, approximately one half will be we describe the REGARDS study design. white and one half African-American, and within each region-race stratum, approximately one half will be male and one half female. A letter and study brochure are sent to each potential participant Objectives of REGARDS approximately 2 weeks prior to attempting telephone contact. Ini- tially, only the individual listed in the database was considered a potential participant. After recruitment of approximately ¼ of the The primary aims of REGARDS are associated with sample, because of concerns that non-heads-of-household could be geographic and racial/ethnic (African-American vs. underrepresented by the commercially available list, a household white) differences in stroke. The primary aims are: enumeration approach and selection of a ‘random’ household (1) To provide national data on stroke incidence and member was implemented. Trained interviewers make up to 15 contact attempts during day, evening, weekday and weekend case fatality and assess geographic variations and racial calling shifts. Upon reaching a household resident, the household differences in these measures. is enumerated and one resident aged 6 45 is randomly selected and (2) To provide national data on prevalence and levels screened for eligibility. Exclusion criteria include race other than of stroke risk factors and assess geographic and racial African-American or white, active treatment for cancer, medical variation in the prevalence of these risk factors. conditions that would prevent long-term participation, cognitive impairment judged by the telephone interviewer, residence in or (3) To assess the degree to which geographic and racial inclusion on a waiting list for a nursing home, or inability to com- variations in stroke incidence, case fatality and mortality municate in English. Potential participants who respond ‘don’t are attributable to variations in risk factor prevalence. know’ to questions