Prevalence of diabetes/ hyperglycemia and associated cardiovascular risk factors in blacks and whites: Chicago Heart Association Detection Project in Industry

Prevalence rates of diabetes, asymptomatic hyperglycemia, and cardiovascular risk factors were examined in an employed population of 28,895 whites and 2807 blacks, ages 25 to 84 years. Diabetes had been previously diagnosed in this population among approximately 3% of the males of both races and 2% of the females. Plasma glucose 1 hour after a 50 gm oral load was highest among white males (141 mgjdl), similar and at intermediary levels among black males (134 mg/dl) and white females (135 mg/dl), and lowest among black females (126 mg/dl). A divergent pattern of obesity was observed, however, with black females being by far the most overweight. Preliminary mortality data for males suggest that both blacks and whites with diabetes have sizably higher death rates than those without diabetes; a black-white differential is not apparent. (AM HEART J 108:827, 1984.)

Richard Cooper, M.D., Kiang Liu, Ph.D.,* Jeremiah Stamler, M.D.,

James A. Schoenberger, M.D., Richard B. Shekelle, Ph.D., Patricia Collette, M.A., and Susan Shekelle Chicago, IZZ.

Vital statistics records demonstrate that death rates from cardiovascular (CV) diseases are higher among blacks than whites in the United States.‘, * Most of the large-scale epidemiologic studies that have served as the basis for delineating specific risk factors have not included blacks, however, and the data base for direct black-white comparisons is limited.3,4 Diabetes mellitus is an important risk factor for CV diseases, and death rates from diabe- tes are higher among blacks than whites.5 Whether the prevalence of diabetes is higher among blacks remains uncertain, however.4 The impact of diabetes

From the Department of Community Health and Preventive Medicine, Northwestern University Medical School, the Department of Preventive Medicine, Rush-Presbyterian-St. Luke’s Medical Center, and the Chicago Heart Association.

Supported by grants from the Chicago Heart Association, American Heart

Association, and Illinois Heart Association, and by grants No. 2 RO 1 HL15174 and No. 5 RO 1 HL21020 from the National Heart, Lung and Blood Institute of the U.S. Public Health Service, Ciba-Geigy, CPC International (Best Foods), Marstellar (Flora Information Service), and the Chicago Health Research Foundation.

Reprint requests: Richard Cooper, M.D., Department of Community Health and Preventive Medicine, Northwestern University Medical School, 303 E. Chicago Ave., Chicago, IL 60611.

*Recipient of a Research Career Development Award (No. IK04HL005577) from the National Heart, Lung and Blood Institute.

on mortality among blacks has not been previously reported. In this paper we describe the prevalence of diabetes and associated CV risk factors in a popula- tion of employed people in Chicago, Illinois. Prelim- inary mortality rates for men are also reported.

METHODS

The background and methodology of the Chicago Heart Association Detection Project in Industry (CHA Detec- tion Project) have been described in detail elsewhere.6.l Briefly, during the period from November 7, 1967, to January 8, 1973, examinations were given to 39,573 indi- viduals employed in 84 companies and organizations in Chicago. The volunteer rate was approximately 55% of the work force employed by these firms. The total number of persons screened for each of the four major sex-race groups were 20,233 white males, 14,368 white females, 1494 black males, and 2330 black females. The cohort selected for analysis here was limited to participants in the age range from 25 to 64 years without missing data for all the variables considered, making the sample size 17,750 white males, 11,145 white females, 1191 black males and 1416 black females.

The survey data were collected with a standardized protocol by a specially trained team of nurses and techni- cians. Blood for plasma glucose was drawn 1 hour after a 50 gm oral load from those individuals not currently receiving treatment for diabetes. Laboratory facilities of

827

828 Cooper et al. September, 1984

American Heart Journal

Table I. Prevalence (per 1000) of previously diagnosed diabetes in black and white males and females, by treat- ment status: CHA Detection Project*

Diagnostic White Black White Black

category males males females females

Treated 14.5 (2X)? 17.5 (16) 7.9 (100) 5.5 (5)

Untreated 16.8 (267) 13.8 (16) 12.8 (143) 19.0 (21)

Total 31.3 (482) 31.3 (32) 20.7 (243) 24.5 (26)

*Age standardized, ages 25 to 64 years tNumber of cases.

Table II. Mean l-hour postload plasma glucose levels in black and white males and females, by age: CHA Detec- tion Project*

Mean glucose levels (mg/dl)

Age White Black White Black

hi-) males males females females

25-34 117.9 115.9 117.4 111.9

35-44 134.6 124.6 128.7 123.3

45-54 149.2 142.4 140.9 131.1

55-64 160.3 153.0 151.8 136.9

Age 140.5 134.0 134.7 125.8

standardized

*Excludes treated diabetic patients.

the Chicago Health Research Foundation and the Chicago Health Department were utilized for biochemical analy- ses; they had been designated as a regional reference center for glucose and cholesterol determinations by the Centers for Disease Control, in Atlanta. Venous blood samples, collected in plain glass tubes for serum cholester- ol and in fluoridated tubes for plasma glucose, were spun within 2 hours to separate the cells. Plasma glucose was measured with the AutoAnalyzer adaptation of Hoffman’s methods; for serum cholesterol the AutoAnalyzer adapta- tion of the method of Levine and Zak9 was used. Technical error, calculated monthly on the basis of 10% blind duplicate samples, averaged 2.4 mg/dl for plasma glucose and 5.1 mg/dl for serum cholesterol.

nation Surveys (NHES) of the U.S. Public Health Service, the Framingham population, and the several population studies in the national cooperative Pooling Project. The following parameters were found to be very similar for the Chicago Heart Association Project screenees compared with those recorded for other U.S. adult populations: mean values, standard deviations, coefficients of varia- tion, distributions, correlation matrices, and patterns in patients classified by age, sex, race, height, weight, relative weight,* body mass index, systolic and diastolic blood pressure, serum cholesterol and uric acid levels, and plasma glucose levels 1 hour after 50 gm oral load.

For purposes of this analysis, diabetes was defined as a previous diagnosis by a physician, whether the patient was currently under treatment or not. Asymptomatic hyper- glycemia was defined as a plasma glucose level 1200 mg/dl 1 hour after a 50 gm oral load or a casual plasma glucose level 2160 mg/dl. The two categories-clinical diabetes and hyperglycemia-were then considered together. The possibility that diuretic therapy for hyper- tension would have had a significant impact on blood sugar-and thereby on the prevalence of asymptomatic hyperglycemia-was examined by excluding all persons currently receiving antihypertensive medications. Only small changes in age-, sex-, and race-specific rates of hyperglycemia were noted (all less than 8% ), and the rank order of these groups was not altered. For preservation of the entire cohort, therefore, persons receiving treatment for hypertension were included in most of the analyses; they were excluded only in the analysis of blood pres- sure.

As of July 1982, mean follow-up for the entire cohort was 120 months, and vital status information was avail- able on 96.3% of the participants. For the individual sex-race groups, follow-up was 98.1% for white males, 95.6% for black males, 94.8% for white females, and 92.2% for black females.

Age standardization was accomplished by averaging values for the four lo-year age groups.

The additional data of relevance to this report related to age, sex, and race; height and weight; casual blood pressure (Korotkoff sounds, phases I and V); history of diabetes; history of treatment for diabetes; current status with respect to treatment for diabetes; and history of cigarette smoking.

Data were entered into the computer file, checks were made for any duplication of persons, and a comprehensive edit was done of the file. All edited data were stored on computer tape. Analyses were carried out to evaluate whether the age-sex-race-specific findings for this popula- tion were similar to those for other population studies in the United States-e.g., the random samples of the U.S. adult population screened by the National Health Exami-

RESULTS

Approximately 3% of the males and 2 5% of the females screened in this study had a previous diag- nosis of diabetes mellitus (Table I). This condition was more commonly diagnosed in males than in females of both races; this could be accounted for by a higher prevalence of treated diabetes among the males. The sex-specific differences between races were small.

Mean postload glucose levels were highest among white males and lowest among black females, with black males and white females having very similar

*Relative weight was computed on the basis of tables of desirable weight derived from the experience of the insurance industrylO; it is the ratio of observed weight to desirable weight for height and sex.

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Number 3, Part 2 Diabetes and CHD in blacks and whites 029

Table III. Prevalence (per 1000) of diabetes or hyperglycemia* in black and white males and females, by age: CHA Detection Project

Age (yr) White males Black males White females Black females

25-34 30.0 ( 167)t 29.2 (14) 27.9 ( 60) 20.7 (15) 35-44 86.1 ( 406) 56.4 (19) 66.2 ( 159) 54.8 (23) 45-54 155.1 ( 703) 142.9 (36) 124.7 ( 502) 105.0 (21) 55-64 230.0 ( 675) 172.1 (21) 165.6 ( 426) 70.4 ( 5)

Age standardized 125.3 (1951) 100.2 (90) 96.0 (1147) 62.7 (64)

*Diabetes or hyperglycemia defined as positive history or l-hour postload plasma glucose levels z 200 or casual glucose levels > 160. tNumber of cases.

Table IV. Prevalence (per 1000) of severe obesity* in black and white males and females, by age: CHA Detection Project

Age (yr) White males Black males White females Black females

25-34 57.5 ( 320)1 66.7 ( 32) 64.3 ( 138) 102.1 ( 74) 35-44 79.1 ( 373) 106.8 ( 36) 95.7 ( 230) 152.4 ( 64) 45-54 95.5 ( 433) 111.1 ( 28) 128.2 ( 516) 265.0 ( 53) 55-64 87.3 ( 256) 123.0 ( 15) 162.9 ( 419) 323.9 f 23)

Age standardized 80.1 (1382) 101.9 (111) 112.9 (1303) 210.9 (214)

*Obesity defined as relative weight 2 1.45. tNumber of cases.

intermediary levels (Table II). These differences were consistent for almost all the separate lo-year age groups. The prevalence of glucose intolerance, based on prior diagnosis of diabetes or hyperglyce- mia, followed closely the pattern of mean glucose levels (Table III). That is, white males had a preva- lence rate twice that of black females, with the remaining two sex-race groups falling halfway between. With these combined criteria the preva- lence of diabetes and hyperglycemia was three to five times higher than with medical history alone.

The prevalence of severe obesity in this popula- tion was the opposite from the pattern for diabetes and hyperglycemia (Table IV). Black females were much more obese at every age; females of both races were more overweight than males of the same race.

Correlation coefficients were computed among plasma glucose and related variables (Table V). The relationships were similar in all sex-race groups, although they were somewhat attenuated as they moved toward those groups with lower prevalence rates of hyperglycemia.

Mean values of the three major CV risk factors and of relative weight for persons with and without diabetes or hyperglycemia are presented in Table VI. The former had higher levels of risk factors in every category examined. Blacks had higher levels of blood pressure than whites. With adjustment for relative weight, the mean values for serum cholester-

Table V. Correlations* among plasma glucose levels in black and white males and females, by age, relative weight, blood pressure, and serum cholesterol levels: CHA Detection Project

Plasma glucose level 1 hour after 50 gm oral load

White Black White Black

Variable males males females females

Age 0.355t 0.317t 0.285t 0.228t

Relative weight 0.1677 0.196t 0.148t 0.138t Blood pressuref (diastolic) 0.235t 0.278t 0.209t 0.166t Serum cholesterol 0.155t 0.1457 0.177t O.OSO$

*Exclude treatment for diabetes. tp 5 0.001. $Exclude treatment for hypertension. §p < 0.05.

01 and blood pressure, as well as the mean values for cigarette use, remained higher in persons with dia- betes or hyperglycemia compared with those with normoglycemia.

The number of deaths in the cohort of black females over the follow-up period was insufficient to allow estimates of death rates among those with diabetes. A comparison of black and white males was possible, however. Persons with diabetes or hyper- glycemia in both races had age-adjusted death rates over 50% higher than normoglycemic persons (Ta- ble VII); black males had only slightly increased

830 Cooper et al. September, 1994

American Heart Journal

Table VI. Mean values of cardiovascular risk factors in black and white males and females, by diagnostic category: CHA Detection Project*

Risk factor Diagnostic categor-v White males Black males White females Black females

Systolic BP (mm Hg)t

Diastolic BP (mm Hg)t

Serum cholesterol (mg/dl)

No. of cigarettes smoked/day

Relative weight

DM/‘H 144.6 147.9 137.0 146.9

Non-DM/H 138.5 141.8 131.8 134.3

DM/H 84.9 89.9 81.1 88.8

Non-DM/H 81.6 84.6 77.4 80.3

DM/H 210.0 211.9 215.3 209.7

Non-DM/H 205.7 201.9 208.5 205.6 DM/H 11.6 10.6 8.0 9.2

Non-DM/H 9.5 8.9 7.1 5.7

DM/H 1.25 1.30 1.20 1.32 Non-DM/H 1.22 1.22 1.18 1.26

BP = Blood pressure; DM = diabetes mellitus; H = hyperglycemia. *Age standardized, ages 25 to 64 years. tExcludes those treated for hypertension.

death rates among those with normoglycemia, com- pared with white males, and there were identical black-white rates for persons with diabetes or hyper- glycemia. About half the deaths in this cohort were coded to CV causes, and the pattern by race and presence of diabetes or hyperglycemia was similar (Table VIII). Thus, although persons with diabetes or hyperglycemia had a 50 % and 100% increase in mortality among blacks and whites, respectively, rates for both races were comparable. It must be recognized that these estimates are based on small numbers.

DISCUSSION

In this employed population the prevalence of diabetes and hyperglycemia was found to be highest among white males, intermediate and similar among both black males and white females, and lowest among black females. The rate of previously diag- nosed diabetes was similar in black and white males and, again, among females of both races; the desig- nation of hyperglycemia accounted for most of the difference in prevalence rates. The opposite pattern for obesity emerged, however; the age-standardized rates of obesity were highest for black females, followed by white males, black males, and, finally, white females. Adjusting diabetes prevalence by obesity would therefore accentuate the low rates for black females. A consistent finding in all four sex- race groups was higher levels of the three major risk factors, as well as obesity, in persons with diabetes compared to those without diabetes.

Two important potential sources of bias in these data must be taken into account. In an employed population, not only will persons with a significant illness be excluded to some extent, but this effect may apply differentially to various sex-race-occupa-

tion groups. Thus white males in professional jobs might be more likely to be able to work with a diagnosis of clinical diabetes. Additionally, the over- all response rate of only 55% makes it possible that the observed patterns may not be representative.

Precise comparison of this survey with previous work is difficult because of varying methods and endpoint definitions. Self-reported rates of diabetes are roughly comparable to a national U.S. survey and two community screening projects, although sufficient age-specific data are lacking.‘l-l3 Reported mean glucose levels were a good deal higher in a large survey by a prepaid health plan, reflecting in part the use of a 75 gm load and serum-rather than plasma-glucose levels .14 The only reported direct study of glucose tolerance based on a cross section of the U.S. population utilized a 50 gm load and yielded glucose levels similar to those reported here, with the exception that white males in our sample had sizably higher values.15 The grouping by diabe- tes and hyperglycemia employed in this analysis includes many individuals with only hyperglycemia. Although the prognostic significance of asymptom- atic hyperglycemia in relation to CV disease is uncertain,16 this definition provides a basis for com- parison of glucose tolerance on a cross-sectional basis.

Is diabetes more common in blacks than whites in the United States? In a comprehensive review, West5 cites several studies demonstrating a lower prevalence of diabetes and lower death rates in blacks than whites before World War II; this was particularly true for poor and rural blacks.5 Addi- tional surveys confirm a low prevalence of diabetes in most parts of Africa over the first half of this century.5*‘7 Blacks have lost this advantage, at least in relation to mortality. Through the late 1970s in

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Number 3, Part 2 Diabetes and CHD in blacks and whites 831

Table VII. All-cause death rates (per 1000) in black and white males with diabetes or hyperglycemia vs those with normoglycemia: CHA Detection Project*

Black1

White Black white

Diagnostic group males males ratio

Diabetes or hyperglycemia 96.0 (240)t 95.7 ( 9) 1.00 Normoglycemia 52.3 (618) 62.7 (45) 1.20 Ratio of diabetes and 1.84 1.53

hyperglycemia to normoglycemia

*Age standardized, ages 25 to 64 years. tNumber of deaths.

the United States, the mortality trend for diabetes was upward for blacks but declining for whites. In 1977 twice as many deaths were certified to diabetes among blacks as whites. I8 The age-adjusted rate for white males was 9.8/100,000 and 16.3 for “all other” males; for females the rates were 9.0 for whites and 22.0 for “all other” females. Higher rates were observed for nonwhites in every age group. Although nonwhite groups other than blacks, notably Ameri- can Indians, have very high rates of diabetes, blacks make up over 90% of the nonwhite U.S. population and must have, in the main, determined the non- white rates.

The prevalence data are not generally consistent with the vital statistics. Based on a national proba- bility sample, the prevalence of self-reported diabe- tes was 13.3/1000 for nonwhites and 12.1 for whites in the United States in 1964-1965.1s Comparable data in 1973 demonstrate an increase to 23.9/1000 for nonwhites and 19.9 for whites.” It is of interest that between the ages of 45 and 64 years the rates for blacks were almost twice those for whites (70 vs 40/1000). In the NHES of 1960-1962 both black males and black females had modestly higher glu- cose levels than their white counterparts at every age, except for females over 75 years of age.15 Treated individuals were excluded, and it is not clear whether correction for differential levels of treatment between blacks and whites played a role. After a separation of the sample into three income categories, glucose intolerance among blacks relative to whites appeared to be concentrated in the highest income group. The Kaiser Permanents program reported glucose tolerance in 88,000 whites and 12,000 blacks from northern California who were studied between 1964 and 1968.14 At all ages and for both sexes, blacks had strikingly lower levels of blood sugar. Thus for white males the mean l-hour postload blood sugar level was 177 mg/dl for black

Table VIII. Cardiovascular death rates (per 1000) in black and white males with diabetes or hyperglycemia vs those with normoglycemia: CHA Detection Project*

White

males

Black/ Black white

males ratio

Diabetes or hyperglycemia 54.5 (13717 47.6 ( 4) 0.87 Normoglycemia 26.6 (304) 33.4 (20) 1.26 Ratio of diabetes and 2.05 1.43

hyperglycemia to normoglycemia

*Age standardized. tNumber of deaths.

males, 156 mg/dl; white females had a mean level of 179 mg/dl and black females, 153 mg/dl. Differences in age, education, obesity, or use of thiaxides did not account for the differences in blood sugar levels.

The prevalence findings do not lend themselves to any simple explanation. Except for slightly higher levels of blood sugar in the 1960-1962 NHES data, there is no evidence that blacks have poorer glucose tolerance than whites. Although males have similar levels of obesity, black females in the United States are more obese than white femaleszO; this finding alone would indicate the possibility of a higher prevalence of diabetes. In fact, the data presented in this report are consistent with those from the Kaiser program and suggest that black females are resistant to diabetes even when more obese. The three meth- ods of assessing racial differences in diabetes thus yield inconsistent results. Despite a similar or lower prevalence of glucose intolerance in the three studies available, in a national sample the self- reported history of diabetes was 20% more common in blacks, and US. death rates are twice as high.

Genetic factors have not been demonstrated to play a role in black-white patterns of diabetes. As noted by West, “Most of the recent evidence sug- gests that environmental and social circumstances are more important than race in determining sus- ceptibility to typical adult-onset diabetes. After corrections for adiposity very little difference could be found in rates of maturity onset diabetes [in an international comparative study involving 13 soci- eties] even though rates varied as much as ten- fold.“5

The CHA Detection Project involved an employed population, and the Kaiser sample is heavily weighted by working adults. It is possible that there are differential pressures to exclude dia- betic blacks from the work force, compared with whites. For such a hypothesis to be consistent, one

832 Cooper et al.

would also have to postulate that similar forces are at work against white females. That is, even though more obese, white females had slightly lower rates of diabetes than black males and much lower rates than white males.

Higher mortality rates among blacks are consis- tent with a more common occurrence of other serious disease, particularly CV disease. If this fac- tor were strong enough, it could in part account for the unexpectedly lower levels of blood glucose in blacks as measured in surveys. Selective mortality would leave a healthier cohort as survivors. Use of multiple-cause data from death certificates might help clarify this question. This effect is an unlikely explanation, however, of the large discrepancy observed between death rates and prevalence. Our data do not suggest that black diabetic or hypergly- cemic males markedly higher death rates, even with an excess CV risk. Again, the potential impact of a differential employment disadvantage against sicker members of the black population must be consid- ered. It is also possible that a more general phenom- enon relating to the accuracy of vital statistics or differential case fatality could be a factor. The finding of lower or similar prevalence rates and/or levels of risk factors in blacks relative to whites in the face of much higher mortality is not isolated to diabetes. One might note, for example, alcohol con- sumption and cirrhosis, as well as cigarette smoking and lung cancer and (possibly) coronary heart dis- ease.21-23

A complex biologic and social interaction is undoubtedly involved in this pattern of black-white differentials.24 The apparent inconsistencies that emerge in this study of diabetes prevalence under- score the need for prospective studies that permit direct comparisons across black-white and male- female groups.

Acknowledgment is gratefully extended to all those involved in the Chicago Heart Association Detection Project in Industry: Louis de Boer, past executive director, and Kay Westfall, pro- gram director; the project staff: Pamela Bessmond, Thelma Black, Clarice Blanton, Joan Carothers, Arlene Dungca, Mary Ann Foelker, Susan Forkos, Carol Fugenzi, Harold Gram, Jean Graver, Inger Hansen, Cherry Latimer, Mary Newman, Peggy Powell, Karen Strentz, R.N., and Suzann Ward, R.N.; and the volunteer members of the Heart Disease Detection Committee of the Chicago Heart Association and its subcommittees: Howard Adler, Ph.D., Rene Arcilla, M.D., Robert Arzoecher, Ph.D., Richard A. Carleton, M.D., Angelo Cottini, Edwin Duffin, M.D., Morton B. Epstein, Ph.D., Robert Fitzgerald, M.D., Phillip Freedman, M.D., Burton J. Grossman, M.D., Mark M. Lepper, M.D., Robert J. Hilker, M.D., Robert S. Kassriel, M.D., Howard A. Lindberg, M.D., Clinton L. Lindo, M.D., Gerald Masek, Ph.D., Richard McNamara, Robert A. Miller, M.D., Robert Mosley, Jr., M.D., Milton H. Paul, M.D., Willie Reedus, R.N., Raymond

September, 1984

American Heart Journal

Restivo, current executive director, Wallace Salzman, M.D., Robert Sessions, Howard H. Sky-Peck, Ph.D., Donald Singer, M.D., Lachichida Sinha, M.D., Grace Smedstead, Ralph Spring- er, J. Martin Stoker, M.D., Carl Vogel, Ira T. Whipple, M.S., and Quentin D. Young, M.D.

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18. Vital Statistics of the United States, 1977. Hyattsville, Md, 1981, National Center for Health Statistics, U.S. Department of Health and Human Services.

19. Characteristics of persons with diabetes, United States: July 1964 to June 1965. Vital and Health Statistics, series 10, No 40. Washington, DC, 1967, National Center for Health Statis- tics.

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20. Weight and height of adults 18-74 years of age: United States, 1971-74. Vital and Health Statistics, series 11, No 211. Washington, DC, 1979, National Center for Health Statis- tics.

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Miller WJ, Cooper R: Rising lung cancer death rates among black men: The importance of occupation and social class. J Nat1 Med Assoc 74:349, 1982. Gillum RF: Coronary heart disease in black populations. I. Mortality. AM HEART J 104:839, 1982. Cooper R, Steinhauer MJ, Miller WJ, David R: Racism, society and disease: The social and biological mechanisms of differential mortality. Int J Health Serv 11:389, 1981.

Coronary heart disease in black Americans: Suggestions for research on psychosocial factors

Despite the fact that coronary heart dtsease (CHD) is the leading cause of death among U.S. blacks, virtually no information exists on the contribution of psychosocial factors to CHD risk in this population. Studies conducted on U.S. whites suggest that type A behavior may be positively associated with risk for CHD. Other studies on whites suggest that occupational stressors, socioeconomic status, and social mobility may also be important. Studies that examine the contribution of these factors to CHD risk in the black population are needed. Moreover, recent changes in the socioeconomic profile of the U.S. black population present an unusual opportunity to study the role of psychosocial variables in CHD among black Americans. Some of the theoretical and measurement issues that investigators may face in conducting such research are discussed, and some specific suggestions for research are offered. (AM HEART J 108:833, 1984.)

Sherman A. James, Ph.D. Chapel Hill, N.C.

As Gillum1~2 pointed out in his comprehensive reviews, coronary heart disease (CHD) is the leading cause of death among U.S. blacks. Although valid estimates of black-white differences in CHD mor- bidity and mortality are not easy to obtain because of study design differences, regional variations in secular trends, and data quality problems, Gillum’ suggests that CHD death rates among U.S. blacks may now be approaching those of U.S. whites. In contrast to white Americans, however, very little is known about the contribution of biologic and psy- chosocial risk factors to CHD in black Americans. Perhaps some of the articles presented here will help correct this deficiency in knowledge and, in addi-

From the Department of Epidemiology, Shoot of Public Health, Univer- sity of North Carolina.

Supported by Research Career Development Award No. 5 K04 HLOlOll, National Heart, Lung and Blood Institute.

Reprint requests: Sherman A. James, Ph.D., Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, NC 27514.

tion, will provide insights into what directions future research might take.

This article discusses the potential importance of psychosocial factors in determining CHD risk in black Americans. Four classes of psychosocial vari- ables are considered: socioeconomic status (SES), social mobility, occupational stressors, and type A behavior. In this discussion of type A behavior, theoretical and measurement challenges that researchers may face in making valid assessments of this behavior pattern in blacks will be emphasized. Where possible, specific suggestions for future research on each of these four topics will be offered.

SOCIOECONOMIC STATUS

Studies of white populations in the United States and Western Europe have produced an unclear picture regarding whether SES is positively or nega- tively related, or completely unrelated, to risk of CHD. Methodologic factors may explain some of the

833