- Email: [email protected]
A prospective study of dominance and coronary heart disease in the normative aging study
A Prospective Study of Dominance and Coronary Heart Disease in the Normative Aging Study Aron W. Siegman, PhD, Laura D. Kubzansky, PhD, Ichiro Kawachi, MD, Stephen Boyle, MA, Pantel S. Vokonas, MD, and David Sparrow, DSC The purpose of this study was to examine the prospective relation between dominance, as assessed by a Minnesota Multiphasic Personality Inventory (MMPI-2)-derived dominance scale, and incidence of coronary heart disease (CHD), independent of participants’ anger level. The study was performed in the VA Normative Aging Study, an ongoing cohort of older (mean age 61 years) men. A total of 1,225 men who were free of CHD in 1986 completed the MMPI-2. A factor analysis of selected MMPI items provided the basis for the construction of a dominance scale and an anger scale. During an average of 8 years of follow-up, 158 cases of incident CHD occurred, including 29 cases of fatal CHD, 69 cases
of nonfatal myocardial infarction (MI), and 60 cases of angina pectoris (AP). Compared with men reporting the lowest levels of dominance (lower tertile), the multivariate-adjusted relative risk among men reporting the highest levels of dominance (upper tertile) was 1.80 (95% confidence interval [CI] 1.21 to 3.24) for combined nonfatal MI and fatal CHD. Additional adjustment for anger scores did not significantly alter this relation. There was no significant relation between dominance and AP. Our data suggest that dominance is an independent risk factor for CHD in older men. 䊚2000 by Excerpta Medica, Inc. (Am J Cardiol 2000;86:145–149)
esults of previous studies suggest that the tendency to dominate and control others, which exR presses itself, among other ways, in social competi-
In the present study we examined the prospective relation between dominance—as assessed by an Minnesota Multiphasic Personality Inventory (MMPI-2)10 based dominance questionnaire—and CHD in the Normative Aging Study, an ongoing cohort of older men. Because in this cohort the MMPI-2-based dominance scale correlates significantly with anger—albeit only moderately (r ⫽ 0.39)—we controlled for anger (as well as the other traditional CHD risk factors).
1–5
tiveness (hereafter, dominance), may be a risk factor for coronary heart disease (CHD). In these studies dominance was assessed by expressive paraverbal measures, most often by the tendency to interrupt one’s conversational partner or interviewer (which allows one to retain or regain the “floor”). However, these findings are only suggestive, because some of the expressive, paraverbal speech indexes that are characteristic of dominance are also associated with other personality traits and affective states. Thus, frequent interruption of one’s conversational partner is also associated with anger arousal,6,7 which has been identified as a psychosocial risk factor for CHD.8,9 Clearly, we need a study that uses a more direct index of dominance for testing the hypothesized positive relation between dominance and CHD. From the University of Maryland, Baltimore, Maryland; the Department of Health and Social Behavior, Harvard School of Public Health, and Channing Laboratory, Harvard Medical School; the Normative Aging Study, Department of Veterans Affairs Outpatient Clinic; and the Department of Medicine, Boston University School of Medicine, Boston, Massachusetts. This study was supported by grants HL 54098 and AG 02287. The Normative Aging Study is supported by the Cooperative Studies Program/ERIC, Department of Veterans Affairs, and is a component of the Massachusetts Veterans Epidemiology Research and Information Center (MAVERIC), Boston, Massachusetts. Dr. Kawachi was supported by a Career Development Award from the National Heart, Lung and Blood Institute, Bethesda, Maryland; and by the MacArthur Foundation Network on Socioeconomic Status and Health, Chicago, Illinois. Manuscript received July 22, 1999; revised manuscript received and accepted January 31, 2000. Address for reprints: Aron W. Siegman, PhD, Department of Psychology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250. ©2000 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 86 July 15, 2000
METHODS This study was carried out in the Normative Aging Study, which is a longitudinal study of aging established by the Veterans Administration in 1961.11 The study cohort consisted of 2,280 men from the Greater Boston area who were from 21 to 80 years old at the time of entry. Volunteers were screened at entry according to health criteria,11 and were free of known chronic medical conditions (including diabetes mellitus) at the start of follow-up. Assessment of dominance and anger: An MMPI-2 derived dominance scale and an MMPI-2-derived anger scale were used to assess participants’ dominance and anger levels. In 1986, the MMPI-210 was administered by mail to all active cohort members (n ⫽ 1,881). Of the 1,550 men who responded (82.4% response rate), complete and valid questionnaire data were available for 94% (n ⫽ 1,459). The exclusion of 154 men with pre-existing CHD (angina pectoris [AP] or history of myocardial infarction [MI]), plus missing data on some 80 additional participants resulted in a study population of 1,225 men. MMPI-2 items whose content dealt with feelings of anger, hostile attitudes, aggressive behavior, and dominance (as agreed upon by 3 psychologists) were subjected to a factor analysis 0002-9149/00/$–see front matter PII S0002-9149(00)00850-X
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that resulted in 4 independent factors, including a dominance factor and an anger factor. All the items that were ⱖ0.35 on the dominance factor, but ⬍0.25 on all other factors were selected to form a dominance scale. One item that missed these criteria but met our conceptual definition of dominance was added to form a 13-item dominance scale (Appendix A). Similar criteria guided the construction of the 16-item anger scale (Appendix B). Individuals with high scores on the MMPI-2 dominance scale described themselves as assertive, argumentative, defending their rights, and seeking leadership roles. Individuals with high scores on the MMPI-2 anger scale described themselves as irritable, easily angered, hot headed, and smashing things when angry. The internal consistency reliability coefficient (Alpha) for the dominance scale was 0.73, for the anger scale it was 0.82. Measurement of other cardiovascular risk factors:
Every 3 to 5 years, participants in the Normative Aging Study are assessed by physical examination, updating of medical history, and measurement of a variety of biochemical values including serum cholesterol. Cigarette smoking status (current, former, never) was ascertained by a trained interviewer. Current smokers are defined as men who smoke ⱖ1 cigarette per day. Weight and height are measured with the participants wearing only socks and underpants. Body mass index (weight/height2) was then calculated. Blood pressure was measured by an examining physician with a standard mercury sphygmomanometer with a 14-cm cuff. With the subject seated, systolic blood pressures and fifth-phase diastolic blood pressures were measured in each arm to the nearest 2 mm Hg. The average systolic and diastolic blood pressures in both arms were used in analyses. Only 8 individuals in the study population were receiving oral hypoglycemic agents or insulin. Assessment of morbidity and mortality: The average length of follow-up in the present study was 8.0 years (SD, 2.3 years). The present study includes all confirmed CHD end points (AP, MI, and fatal CHD) that occurred during the average 8 years of follow-up. Subjects were censored either at the time of developing a coronary end point (or death) or up to the time of their most recent follow-up visit. A medical history was obtained from each participant at his regular follow-up visit every 3 to 5 years. The hospital records were obtained for every report of a possible CHD event and reviewed by a board-certified cardiologist. The criteria for MI and AP were those used in the Framingham Heart Study.12 MI was diagnosed only when documented by unequivocal electrocardiographic changes (i.e., pathologic Q waves), by a diagnostic elevation of serum enzymes (serum glutamic-oxaloacetic transaminase and lactate dehydrogenase) together with chest discomfort consistent with MI, or by autopsy. AP was diagnosed when the subject reported recurrent chest discomfort lasting up to 15 minutes, which was distinctly related to exertion and relieved by rest or nitroglycerin. If any individual developed ⱖ1 event (e.g., angina, then later, nonfatal MI), he was censored at the time of the 146 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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earlier event. This was done to minimize the bias introduced when individuals change their behavior following the first event. Death from CHD was designated when a death certificate (coded according to the Eighth Revision of the International Classification of Diseases13) indicated an underlying cause of death coded to rubric 410 to 414. The medical records in each instance of CHD death were reviewed by a board-certified cardiologist to ensure accurate coding. Most deaths occurring in this cohort are reported by next of kin or postal authorities. Every year, birthday cards are mailed to participants in the cohort, at which point news of a participant’s death is likely to be reported back to the investigators by the next of kin. Additional opportunities to ascertain the vital status of participants occur when supplemental questionnaires are mailed to participants on an approximately annual basis. Finally, we routinely search the state vital records as well as the records of the Department of Veterans Affairs to pick up deaths that may have gone unreported. Thus, our ascertainment of fatal events is systematic and comprehensive. Data analysis: We ran proportional hazards models using SAS14 to estimate the relative risks of CHD according to 3 different levels of dominance (lower tertile, middle tertile, and upper tertile of participants’ MMPI-2 dominance scale scores), controlling for a range of potential confounding variables ascertained in 1986, including age (years); body mass index (kilogram per square meter); smoking status (never, former, current); systolic and diastolic blood pressures (mm Hg); serum cholesterol level (milligram per deciliter); family history of heart disease (yes/no); and whether the participant drank ⱖ2 drinks of alcohol per day (yes/no). The presence of a linear trend in the relative risks of CHD was tested by entering the dominance score as a continuous variable in the regression models. We also determined the relative risks for CHD as a function of the 3 levels of dominance, this time controlling for participants’ MMPI-2 anger scale scores, plus the traditional CHD risk factors.
RESULTS The mean dominance score among subjects with complete and valid data was 6.66 (SD, 2.76; range 0 to 12). The distribution of responses to the dominance scale in the entire cohort is shown in Figure 1. Table I presents the distribution of CHD risk factors as a function of dominance level. Compared with subjects with low dominance scale scores, subjects with high dominance scale score were younger, heavier, and more likely to be current smokers. Age, weight, and smoking are, of course, well-established risk factors for CHD, and therefore, they were covaried in the present study. Dominance and coronary heart disease: During the follow-up period, 158 new coronary events occurred in the 1,225 men: 69 cases of nonfatal MI, 29 cases of fatal CHD, and 60 cases of AP. Cases of nonfatal MI JULY 15, 2000
rived dominance scale scores and total CHD (even after adjusting for traditional risk factors). The multivariate relative risk of a 1.0 SD increment in the dominance scale was 1.35 (95% CI 1.08 to 1.68). When also controlling for anger, dominance maintained an independent effect on total CHD (the multivariate relative risk of a 1.0 SD increment in the dominance scale was 1.27; 95% CI 1.00 to 1.62). There was no significant relation between dominance and AP.
DISCUSSION
FIGURE 1. Distribution of responses to the dominance scale of the MMPI-2. The number of subjects is indicated above each bar.
TABLE I Distribution of Coronary Heart Disease (CHD) Risk Factors According to MMPI-2 Dominance Scores MMPI-2 Dominance Scores CHD Risk Factors Mean age (yrs) Current smokers CHD family history Alcohol: 2⫹ drinks/day Body mass index (kg/m2) Blood pressure Systolic (mm Hg) Diastolic (mm Hg) Serum cholesterol level (mg/dl)
Lower Tertile Middle Tertile Upper Tertile (n ⫽ 406) (n ⫽ 470) (n ⫽ 349) 61 29% 36% 33% 26
129 78 248
60 35% 33% 39% 27
128 79 246
60* 35%† 30% 27% 27
127 78 248
To our knowledge, this study is the first to report a significant prospective relation between questionnaire assessed dominance and CHD in men. Moreover, this relation remained significant even after adjusting for traditional risk factors and anger. There are 4 other studies,1–5 in addition to the present one, that have also reported a significant positive relation between social dominance and CHD. A major difference between these previous studies and the present one is that in the previous studies dominance was indexed by a dominant speech style, whereas in the present study participants’ dominance level was assessed by means of a questionnaire. The fact that both types of assessment predict CHD outcome adds to the construct validity of the hypothesized dominance-CHD relation. Dominance is related not only to documented CHD (MI and sudden death),1,3,4 but also to positive angiographic findings,2 and to ischemia as determined by positive thallium stress test findings,5 which also adds to the validity of the hypothesized dominance-CHD relation. The pathophysiology of the dominance-CHD relation:
*p ⬍0.05; †p ⬍0.001.
and fatal CHD were combined to form the category of total CHD (n ⫽ 98). Analyses based on comparisons of subjects who scored in the lower third, middle third, and upper third of the MMPI-2 dominance scale in relation to CHD risk are shown in Table II. Compared with men scoring in the lower tertile of the dominance scale, the age-adjusted relative risk of CHD in men scoring in the upper tertile of the dominance scale was 2.20 (95% confidence intervals [CI] 1.36 to 3.56) for combined nonfatal MI and fatal CHD, 1.99 (95% CI 1.11 to 3.56) for nonfatal MI, and 2.96 (95% CI 1.25 to 7.04) for fatal CHD. Dominance scores were not significantly related to AP (Table II). With the exception of the relative risk for fatal CHD, after adjustment for coronary risk factors, these estimates did not change substantially. Additional adjustment for participants’ anger scores did not significantly alter the relative risk for total CHD (Table II). With the adjustment for anger, however, the relative risk for fatal CHD was almost significant, although the relative risk for nonfatal MI was no longer significant (Table II). When dominance was examined as a continuous variable, there was a statistically significant (p ⬍0.01) positive relation between participants’ MMPI-2-de-
Working with cynomolgus monkeys, Kaplan et al15,16 found that dominant males living in an unstable social environment were at an increased risk for atherosclerosis, presumably because of the more frequent elicitation of extreme cardiovascular responses in such environments. Smith and colleagues,17,18 working with humans, reported that attempts to exert dominance were associated with heightened cardiovascular reactivity levels. The relevance of these findings is that heightened cardiovascular reactivity is a risk factor for CHD.19,20 Hyperlipidemia may also be involved in the dominance-CHD relation: 1 study21 found a significant positive relation between questionnaire-assessed dominance and serum triglyceride concentration, but not with serum cholesterol concentration. Another study,22 however, found that questionnaire-assessed dominance did correlate positively and significantly with total serum cholesterol levels, but only in low physically fit individuals. Finally, we must also consider indirect pathways, such as smoking and diet, which have been found to play a significant role in the hostility-CHD relation. Dominance and aggression: Ethologists23 tend to view dominance as a form of aggressive behavior. Social psychologists,24 however, distinguish between 2 types of aggression: anger-driven aggression, or “hot” aggression, and instrumental aggression, or “cold” aggression. The question, then, is: is domi-
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TABLE II Age-adjusted, Multivariate-adjusted, and Anger-adjusted Relative Risks (RR) of Coronary Heart Disease (CHD) and Angina According to Dominance Levels Level of Dominance End Point Total CHD (fatal and nonfatal) Cases Age-adjusted RR Multivariate RR† Anger-adjusted RR‡ Nonfatal MI Cases Age-adjusted RR Multivariate RR† Anger-adjusted RR‡ Fatal CHD Cases Age-adjusted RR Multivariate RR† Anger-adjusted RR‡ AP Cases Age-adjusted RR Multivariate adjusted RR† Anger-adjusted RR‡
Lower Tertile
Middle Tertile*
Upper Tertile*
27 1.00 1.00 1.00
27 0.93 (0.54–1.60) 0.90 (0.52–1.55) 0.92 (0.52–1.64)
44 2.20 (1.36–3.56) 1.80 (1.21–3.24) 1.83 (1.05–3.20)
19 1.00 1.00 1.00
21 0.97 (0.52–1.83) 0.99 (0.52–1.86) 1.02 (0.53–1.98)
29 1.99 (1.11–3.56) 1.91 (1.05–3.45) 1.65 (0.85–3.20)
8 1.00 1.00 1.00
6 0.80 (0.28–2.31) 0.64 (0.21–1.89) 0.64 (0.19–2.11)
15 2.96 (1.25–7.04) 2.26 (0.93–5.48) 2.75 (0.98–7.73)
16 1.00 1.00 1.00
27 1.50 (0.81–2.79) 1.45 (0.77–2.73) 1.19 (0.61–2.33)
17 1.35 (0.68–2.67) 1.30 (0.67–2.71) 0.96 (0.44–2.09)
*Values in parentheses are 95% CIs. † Adjusted for age, smoking, systolic and diastolic blood pressures (mm Hg), serum total cholesterol level (mg/dl), body mass index (kg/m2), family history of CHD, and alcohol intake (2 drinks per day). ‡ Adjusted for MMPI-2 anger scores plus the covariates of the multivariate analyses.
nance an expression of anger-driven aggression, of instrumental aggression, or of both? Evidence25 indicates that dominance, when measured behaviorally by interruptive and/or simultaneous speech, does not correlate significantly with anger-driven aggression scores (specifically, with Spielberger’s26 STAXI anger-out scores), at least not in men. In men, there was a nonsignificant negative correlation between the 2 measurements. It would seem, then, that dominance is not simply a manifestation of anger-driven aggression. In contrast, a number of items with significant loadings on the dominance factor suggest instrumental aggression (items no. 1, 3, 5).26 Study limitations: The most important limitation of the present study is that it is based on a predominantly white, male cohort. Previous studies1,5 suggest that dominance is a risk factor for CHD for men but not for women. Future studies will need to examine the dominance-CHD relation in women and nonwhite populations. In the present study, dominance was a significant risk factor for nonfatal MI, and a near significant risk factor for fatal CHD (when also adjusted for anger), but not for AP. However, anger, as reported by Kawachi et al,8 was the strongest risk factor for AP. Could it be that dominance and anger are each associated with different end points? Given the small number of cases in some of the groups (only 29 fatal CHD cases), further research, with more cases for each end point, is needed to confirm the suggested differential relations between dominance, anger, and CHD outcome. 148 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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APPENDIX A
MMPI-2 Factor Analytically Derived Dominance Items:* 1. When people do me a wrong, I feel I should pay them back if I can, just for the principle of thing. 2. I frequently find it necessary to stand up for what I think is right. 3. I have at times stood in the way of people who were trying to do something, not because it amounted to much but because of the principle of the thing. 4. I like to let people know where I stand on things. 5. I am often so annoyed when someone trieds to get ahead of me in a line of people that I speak to that person about it. 6. I have at times had to be rough with people who were rude or annoying. 7. I am often inclined to go out of my way to win a point with someone who has opposed me. 8. I am usually very direct with people I am trying to correct or improve. 9. I do not try to cover up my poor opinion or pity of people so that they won’t know how I feel. 10. I strongly defend my opinions as a rule. 11. When people do something that makes me angry, I let them know how I feel about it. 12. I like to drive a hard bargain. 13. I like making decisions and assigning jobs to others.
*True ⫽ 1; false ⫽ 0. Range of possible scores: 0 to 13.
APPENDIX B
MMPI-2 Factor Analytically Derived Anger Scale Items:† 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.
At times I feel like swearing. At times I feel like smashing things. I have very few quarrels with members of my family (reverse). Sometimes when I am not feeling well, I am irritable. Often I cannot understand why I have been so irritable and grouchy. It makes me impatient to have people ask my advice or otherwise interrupt me when I am working on something important. I get mad easily and then get over it soon. I easily become impatient with people. I am not easily angered (reverse). I get angry when my friends or family give me advice on how to live my life. I am often said to be hot headed. I am often sorry because I am so irritable and grouchy. I often become very irritable when people interrupt my work. Sometimes I get so angry and upset, I do not know what comes over me. I have become so angry with someone that I have felt as if I would explode (or reverse). I almost never lose self-control (reverse).
True ⫽ 1; false ⫽ 0. Range of possible scores: 0 to 16.
†
1. Siegman AW, Townsend ST, Civelek AC, Blumenthal RS. Antagonistic
behavior dominance, hostility and coronary heart disease. Psychosom Med 2000; 62:248 –257. 2. Siegman AW, Feldstein S, Tommaso C, Ringel N, Lating J. Expressive vocal behavior and the severity of coronary artery disease. Psychosom Med 1987;49: 545–561. 3. Houston BK, Chesney MA, Black GW, Cates DS, Hecker MHL. Behavioral clusters and coronary heart disease risk. Psychosom Med 1992;54:447– 461. 4. Houston BK, Babyak MA, Chesney MA, Black G, Ragland DR. Social dominance and 22-year all-cause mortality in men. Psychosom Med 1997;59:5– 12. 5. Siegman AW. Cardiovascular consequences of expressing, experiencing, and repressing anger. J Behav Med 1993;16:539 –569. 6. Siegman AW, Feldstein S, eds. Nonverbal Behavior and Communication. 2nd Ed. Hillsdale, NJ: Erlbaum Associates, 1978. 7. Siegman AW. Expressive correlates of affective states and traits. In Siegman
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AW, Feldstein S, eds. Multichannel Integrations of Nonverbal Behavior. Hillsdale, NJ: Erlbaum Associates, 1985:37– 68. 8. Kawachi I, Sparrow D, Spiro A III, Vokonas P, Weiss ST. A prospective study of anger and coronary heart disease: The Normative Aging Study. Circulation 1996;94:2090 –2095. 9. Mittleman MA, Maclure M, Sherwood JB, Mulry RP, Tofler GH, Jacobs SC, Friedman R, Benson H, Muller JE. Triggering of acute myocardial infarction onset by episodes of anger. Circulation 1995;92:1720 –1726. 10. Butcher JN, Dahlstrom WG, Graham JR, Tellegen A, Kaemmer B. MMPI-2: Minnesota Multiphasic Personality Inventory-2, Manual for Administration and Scoring. Minneapolis, MN: University of Minnesota Press, 1989. 11. Bell B, Rose CL, Damon A. The Normative Aging Study: an interdisciplinary and longitudinal study of health and aging. Int J Aging Hum Dev 1972;3:5–17. 12. Shurtleff D. Some characteristics related to the incidence of cardiovascular disease and death: Framingham Study, 18-year follow-up. Bethesda, MD: US Dept. of Health, Education, and Welfare, 1974, publication 74 –599. 13. Department of Health, Education, and Welfare. International classification of diseases adapted for use in the United States. 8th Revision. Washington, DC: US Dept. of Health, Education, and Welfare, 1963, publication PHS 1693. 14. SAS/STAT User’s Guide. Version 6, 4th Ed. Cary, NC: SAS Institute Inc, 1990. 15. Kaplan JR, Manuck SB, Clarkson TB. Social status, environment, and atherosclerosis in cynomolgous monkeys. Arteriosclerosis 1982;2:359 –368. 16. Kaplan JR, Botchin MB, Manuck SB. Animal models of aggression and cardiovascular disease. In: Siegman AW, Smith TW, eds. Anger, Hostility, and the Heart. Hillsdale, NJ: Erlbaum Associates, 1994:127–148. 17. Smith TW, Allred KD, Morrison CA, Carlson SD. Cardiovascular reactivity
and interpersonal influence: active coping in a social context. J Pers Soc Psych 1989;56:209 –218. 18. Smith TW, Baldwin M, Christensen A. Interpersonal influence as active coping: effects of task difficulty on cardiovascular reactivity. Psychophysiol 1990;27:429 – 437. 19. Kral BG, Becker LC, Blumenthal RS, Aversano T, Fleisher LA, Yook RM, Becker DM. Exaggerated reactivity to mental stress is associated with exercise induced myocardial ischemia in an asymptomatic high-risk population. Circulation 1997;96:4646 – 4653. 20. Keys A, Taylor AL, Blackburn H, Bloxek J, Anderson JT, Simonson E. Mortality and coronary heart disease among men studied for 23 years. Arch Int Med 1971;128:201–214. 21. Fowkes FGR, Lang GC, Donnan PT, Deary IJ, Riemersma RA, Housley E. Serum cholesterol, triglycerides, and aggression in the general population. Lancet 1992;340:995–998. 22. Greene RA, Houston BK, Holleran SA. Aggressiveness, dominance, developmental factors, and serum cholesterol level in college males. J Behav Med 1995;18:569 –579. 23. Evans RI. Konrad Lorenz: The Man and His Ideas. New York: Harcourt Brace Jovanovich, 1975:35– 48. 24. Berkowitz L. Aggression: Its Causes, Consequences, and Control. New York: McGraw Hill, 1993. 25. Siegman AW, Townsend ST, Blumenthal RS, Sorkin JD, Civelek AC. Dimensions of anger and CHD in men and women: self-ratings versus spouse ratings. J Behav Med 1998;21:315–336. 26. Spielberger CD. Manual for the State-Trait Anger Expression Inventory (STAXI). Odessa, FL: Psychological Assessment Resources, Inc, 1988.
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of nonfatal myocardial infarction (MI), and 60 cases of angina pectoris (AP). Compared with men reporting the lowest levels of dominance (lower tertile), the multivariate-adjusted relative risk among men reporting the highest levels of dominance (upper tertile) was 1.80 (95% confidence interval [CI] 1.21 to 3.24) for combined nonfatal MI and fatal CHD. Additional adjustment for anger scores did not significantly alter this relation. There was no significant relation between dominance and AP. Our data suggest that dominance is an independent risk factor for CHD in older men. 䊚2000 by Excerpta Medica, Inc. (Am J Cardiol 2000;86:145–149)
esults of previous studies suggest that the tendency to dominate and control others, which exR presses itself, among other ways, in social competi-
In the present study we examined the prospective relation between dominance—as assessed by an Minnesota Multiphasic Personality Inventory (MMPI-2)10 based dominance questionnaire—and CHD in the Normative Aging Study, an ongoing cohort of older men. Because in this cohort the MMPI-2-based dominance scale correlates significantly with anger—albeit only moderately (r ⫽ 0.39)—we controlled for anger (as well as the other traditional CHD risk factors).
1–5
tiveness (hereafter, dominance), may be a risk factor for coronary heart disease (CHD). In these studies dominance was assessed by expressive paraverbal measures, most often by the tendency to interrupt one’s conversational partner or interviewer (which allows one to retain or regain the “floor”). However, these findings are only suggestive, because some of the expressive, paraverbal speech indexes that are characteristic of dominance are also associated with other personality traits and affective states. Thus, frequent interruption of one’s conversational partner is also associated with anger arousal,6,7 which has been identified as a psychosocial risk factor for CHD.8,9 Clearly, we need a study that uses a more direct index of dominance for testing the hypothesized positive relation between dominance and CHD. From the University of Maryland, Baltimore, Maryland; the Department of Health and Social Behavior, Harvard School of Public Health, and Channing Laboratory, Harvard Medical School; the Normative Aging Study, Department of Veterans Affairs Outpatient Clinic; and the Department of Medicine, Boston University School of Medicine, Boston, Massachusetts. This study was supported by grants HL 54098 and AG 02287. The Normative Aging Study is supported by the Cooperative Studies Program/ERIC, Department of Veterans Affairs, and is a component of the Massachusetts Veterans Epidemiology Research and Information Center (MAVERIC), Boston, Massachusetts. Dr. Kawachi was supported by a Career Development Award from the National Heart, Lung and Blood Institute, Bethesda, Maryland; and by the MacArthur Foundation Network on Socioeconomic Status and Health, Chicago, Illinois. Manuscript received July 22, 1999; revised manuscript received and accepted January 31, 2000. Address for reprints: Aron W. Siegman, PhD, Department of Psychology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250. ©2000 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 86 July 15, 2000
METHODS This study was carried out in the Normative Aging Study, which is a longitudinal study of aging established by the Veterans Administration in 1961.11 The study cohort consisted of 2,280 men from the Greater Boston area who were from 21 to 80 years old at the time of entry. Volunteers were screened at entry according to health criteria,11 and were free of known chronic medical conditions (including diabetes mellitus) at the start of follow-up. Assessment of dominance and anger: An MMPI-2 derived dominance scale and an MMPI-2-derived anger scale were used to assess participants’ dominance and anger levels. In 1986, the MMPI-210 was administered by mail to all active cohort members (n ⫽ 1,881). Of the 1,550 men who responded (82.4% response rate), complete and valid questionnaire data were available for 94% (n ⫽ 1,459). The exclusion of 154 men with pre-existing CHD (angina pectoris [AP] or history of myocardial infarction [MI]), plus missing data on some 80 additional participants resulted in a study population of 1,225 men. MMPI-2 items whose content dealt with feelings of anger, hostile attitudes, aggressive behavior, and dominance (as agreed upon by 3 psychologists) were subjected to a factor analysis 0002-9149/00/$–see front matter PII S0002-9149(00)00850-X
145
that resulted in 4 independent factors, including a dominance factor and an anger factor. All the items that were ⱖ0.35 on the dominance factor, but ⬍0.25 on all other factors were selected to form a dominance scale. One item that missed these criteria but met our conceptual definition of dominance was added to form a 13-item dominance scale (Appendix A). Similar criteria guided the construction of the 16-item anger scale (Appendix B). Individuals with high scores on the MMPI-2 dominance scale described themselves as assertive, argumentative, defending their rights, and seeking leadership roles. Individuals with high scores on the MMPI-2 anger scale described themselves as irritable, easily angered, hot headed, and smashing things when angry. The internal consistency reliability coefficient (Alpha) for the dominance scale was 0.73, for the anger scale it was 0.82. Measurement of other cardiovascular risk factors:
Every 3 to 5 years, participants in the Normative Aging Study are assessed by physical examination, updating of medical history, and measurement of a variety of biochemical values including serum cholesterol. Cigarette smoking status (current, former, never) was ascertained by a trained interviewer. Current smokers are defined as men who smoke ⱖ1 cigarette per day. Weight and height are measured with the participants wearing only socks and underpants. Body mass index (weight/height2) was then calculated. Blood pressure was measured by an examining physician with a standard mercury sphygmomanometer with a 14-cm cuff. With the subject seated, systolic blood pressures and fifth-phase diastolic blood pressures were measured in each arm to the nearest 2 mm Hg. The average systolic and diastolic blood pressures in both arms were used in analyses. Only 8 individuals in the study population were receiving oral hypoglycemic agents or insulin. Assessment of morbidity and mortality: The average length of follow-up in the present study was 8.0 years (SD, 2.3 years). The present study includes all confirmed CHD end points (AP, MI, and fatal CHD) that occurred during the average 8 years of follow-up. Subjects were censored either at the time of developing a coronary end point (or death) or up to the time of their most recent follow-up visit. A medical history was obtained from each participant at his regular follow-up visit every 3 to 5 years. The hospital records were obtained for every report of a possible CHD event and reviewed by a board-certified cardiologist. The criteria for MI and AP were those used in the Framingham Heart Study.12 MI was diagnosed only when documented by unequivocal electrocardiographic changes (i.e., pathologic Q waves), by a diagnostic elevation of serum enzymes (serum glutamic-oxaloacetic transaminase and lactate dehydrogenase) together with chest discomfort consistent with MI, or by autopsy. AP was diagnosed when the subject reported recurrent chest discomfort lasting up to 15 minutes, which was distinctly related to exertion and relieved by rest or nitroglycerin. If any individual developed ⱖ1 event (e.g., angina, then later, nonfatal MI), he was censored at the time of the 146 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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earlier event. This was done to minimize the bias introduced when individuals change their behavior following the first event. Death from CHD was designated when a death certificate (coded according to the Eighth Revision of the International Classification of Diseases13) indicated an underlying cause of death coded to rubric 410 to 414. The medical records in each instance of CHD death were reviewed by a board-certified cardiologist to ensure accurate coding. Most deaths occurring in this cohort are reported by next of kin or postal authorities. Every year, birthday cards are mailed to participants in the cohort, at which point news of a participant’s death is likely to be reported back to the investigators by the next of kin. Additional opportunities to ascertain the vital status of participants occur when supplemental questionnaires are mailed to participants on an approximately annual basis. Finally, we routinely search the state vital records as well as the records of the Department of Veterans Affairs to pick up deaths that may have gone unreported. Thus, our ascertainment of fatal events is systematic and comprehensive. Data analysis: We ran proportional hazards models using SAS14 to estimate the relative risks of CHD according to 3 different levels of dominance (lower tertile, middle tertile, and upper tertile of participants’ MMPI-2 dominance scale scores), controlling for a range of potential confounding variables ascertained in 1986, including age (years); body mass index (kilogram per square meter); smoking status (never, former, current); systolic and diastolic blood pressures (mm Hg); serum cholesterol level (milligram per deciliter); family history of heart disease (yes/no); and whether the participant drank ⱖ2 drinks of alcohol per day (yes/no). The presence of a linear trend in the relative risks of CHD was tested by entering the dominance score as a continuous variable in the regression models. We also determined the relative risks for CHD as a function of the 3 levels of dominance, this time controlling for participants’ MMPI-2 anger scale scores, plus the traditional CHD risk factors.
RESULTS The mean dominance score among subjects with complete and valid data was 6.66 (SD, 2.76; range 0 to 12). The distribution of responses to the dominance scale in the entire cohort is shown in Figure 1. Table I presents the distribution of CHD risk factors as a function of dominance level. Compared with subjects with low dominance scale scores, subjects with high dominance scale score were younger, heavier, and more likely to be current smokers. Age, weight, and smoking are, of course, well-established risk factors for CHD, and therefore, they were covaried in the present study. Dominance and coronary heart disease: During the follow-up period, 158 new coronary events occurred in the 1,225 men: 69 cases of nonfatal MI, 29 cases of fatal CHD, and 60 cases of AP. Cases of nonfatal MI JULY 15, 2000
rived dominance scale scores and total CHD (even after adjusting for traditional risk factors). The multivariate relative risk of a 1.0 SD increment in the dominance scale was 1.35 (95% CI 1.08 to 1.68). When also controlling for anger, dominance maintained an independent effect on total CHD (the multivariate relative risk of a 1.0 SD increment in the dominance scale was 1.27; 95% CI 1.00 to 1.62). There was no significant relation between dominance and AP.
DISCUSSION
FIGURE 1. Distribution of responses to the dominance scale of the MMPI-2. The number of subjects is indicated above each bar.
TABLE I Distribution of Coronary Heart Disease (CHD) Risk Factors According to MMPI-2 Dominance Scores MMPI-2 Dominance Scores CHD Risk Factors Mean age (yrs) Current smokers CHD family history Alcohol: 2⫹ drinks/day Body mass index (kg/m2) Blood pressure Systolic (mm Hg) Diastolic (mm Hg) Serum cholesterol level (mg/dl)
Lower Tertile Middle Tertile Upper Tertile (n ⫽ 406) (n ⫽ 470) (n ⫽ 349) 61 29% 36% 33% 26
129 78 248
60 35% 33% 39% 27
128 79 246
60* 35%† 30% 27% 27
127 78 248
To our knowledge, this study is the first to report a significant prospective relation between questionnaire assessed dominance and CHD in men. Moreover, this relation remained significant even after adjusting for traditional risk factors and anger. There are 4 other studies,1–5 in addition to the present one, that have also reported a significant positive relation between social dominance and CHD. A major difference between these previous studies and the present one is that in the previous studies dominance was indexed by a dominant speech style, whereas in the present study participants’ dominance level was assessed by means of a questionnaire. The fact that both types of assessment predict CHD outcome adds to the construct validity of the hypothesized dominance-CHD relation. Dominance is related not only to documented CHD (MI and sudden death),1,3,4 but also to positive angiographic findings,2 and to ischemia as determined by positive thallium stress test findings,5 which also adds to the validity of the hypothesized dominance-CHD relation. The pathophysiology of the dominance-CHD relation:
*p ⬍0.05; †p ⬍0.001.
and fatal CHD were combined to form the category of total CHD (n ⫽ 98). Analyses based on comparisons of subjects who scored in the lower third, middle third, and upper third of the MMPI-2 dominance scale in relation to CHD risk are shown in Table II. Compared with men scoring in the lower tertile of the dominance scale, the age-adjusted relative risk of CHD in men scoring in the upper tertile of the dominance scale was 2.20 (95% confidence intervals [CI] 1.36 to 3.56) for combined nonfatal MI and fatal CHD, 1.99 (95% CI 1.11 to 3.56) for nonfatal MI, and 2.96 (95% CI 1.25 to 7.04) for fatal CHD. Dominance scores were not significantly related to AP (Table II). With the exception of the relative risk for fatal CHD, after adjustment for coronary risk factors, these estimates did not change substantially. Additional adjustment for participants’ anger scores did not significantly alter the relative risk for total CHD (Table II). With the adjustment for anger, however, the relative risk for fatal CHD was almost significant, although the relative risk for nonfatal MI was no longer significant (Table II). When dominance was examined as a continuous variable, there was a statistically significant (p ⬍0.01) positive relation between participants’ MMPI-2-de-
Working with cynomolgus monkeys, Kaplan et al15,16 found that dominant males living in an unstable social environment were at an increased risk for atherosclerosis, presumably because of the more frequent elicitation of extreme cardiovascular responses in such environments. Smith and colleagues,17,18 working with humans, reported that attempts to exert dominance were associated with heightened cardiovascular reactivity levels. The relevance of these findings is that heightened cardiovascular reactivity is a risk factor for CHD.19,20 Hyperlipidemia may also be involved in the dominance-CHD relation: 1 study21 found a significant positive relation between questionnaire-assessed dominance and serum triglyceride concentration, but not with serum cholesterol concentration. Another study,22 however, found that questionnaire-assessed dominance did correlate positively and significantly with total serum cholesterol levels, but only in low physically fit individuals. Finally, we must also consider indirect pathways, such as smoking and diet, which have been found to play a significant role in the hostility-CHD relation. Dominance and aggression: Ethologists23 tend to view dominance as a form of aggressive behavior. Social psychologists,24 however, distinguish between 2 types of aggression: anger-driven aggression, or “hot” aggression, and instrumental aggression, or “cold” aggression. The question, then, is: is domi-
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TABLE II Age-adjusted, Multivariate-adjusted, and Anger-adjusted Relative Risks (RR) of Coronary Heart Disease (CHD) and Angina According to Dominance Levels Level of Dominance End Point Total CHD (fatal and nonfatal) Cases Age-adjusted RR Multivariate RR† Anger-adjusted RR‡ Nonfatal MI Cases Age-adjusted RR Multivariate RR† Anger-adjusted RR‡ Fatal CHD Cases Age-adjusted RR Multivariate RR† Anger-adjusted RR‡ AP Cases Age-adjusted RR Multivariate adjusted RR† Anger-adjusted RR‡
Lower Tertile
Middle Tertile*
Upper Tertile*
27 1.00 1.00 1.00
27 0.93 (0.54–1.60) 0.90 (0.52–1.55) 0.92 (0.52–1.64)
44 2.20 (1.36–3.56) 1.80 (1.21–3.24) 1.83 (1.05–3.20)
19 1.00 1.00 1.00
21 0.97 (0.52–1.83) 0.99 (0.52–1.86) 1.02 (0.53–1.98)
29 1.99 (1.11–3.56) 1.91 (1.05–3.45) 1.65 (0.85–3.20)
8 1.00 1.00 1.00
6 0.80 (0.28–2.31) 0.64 (0.21–1.89) 0.64 (0.19–2.11)
15 2.96 (1.25–7.04) 2.26 (0.93–5.48) 2.75 (0.98–7.73)
16 1.00 1.00 1.00
27 1.50 (0.81–2.79) 1.45 (0.77–2.73) 1.19 (0.61–2.33)
17 1.35 (0.68–2.67) 1.30 (0.67–2.71) 0.96 (0.44–2.09)
*Values in parentheses are 95% CIs. † Adjusted for age, smoking, systolic and diastolic blood pressures (mm Hg), serum total cholesterol level (mg/dl), body mass index (kg/m2), family history of CHD, and alcohol intake (2 drinks per day). ‡ Adjusted for MMPI-2 anger scores plus the covariates of the multivariate analyses.
nance an expression of anger-driven aggression, of instrumental aggression, or of both? Evidence25 indicates that dominance, when measured behaviorally by interruptive and/or simultaneous speech, does not correlate significantly with anger-driven aggression scores (specifically, with Spielberger’s26 STAXI anger-out scores), at least not in men. In men, there was a nonsignificant negative correlation between the 2 measurements. It would seem, then, that dominance is not simply a manifestation of anger-driven aggression. In contrast, a number of items with significant loadings on the dominance factor suggest instrumental aggression (items no. 1, 3, 5).26 Study limitations: The most important limitation of the present study is that it is based on a predominantly white, male cohort. Previous studies1,5 suggest that dominance is a risk factor for CHD for men but not for women. Future studies will need to examine the dominance-CHD relation in women and nonwhite populations. In the present study, dominance was a significant risk factor for nonfatal MI, and a near significant risk factor for fatal CHD (when also adjusted for anger), but not for AP. However, anger, as reported by Kawachi et al,8 was the strongest risk factor for AP. Could it be that dominance and anger are each associated with different end points? Given the small number of cases in some of the groups (only 29 fatal CHD cases), further research, with more cases for each end point, is needed to confirm the suggested differential relations between dominance, anger, and CHD outcome. 148 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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APPENDIX A
MMPI-2 Factor Analytically Derived Dominance Items:* 1. When people do me a wrong, I feel I should pay them back if I can, just for the principle of thing. 2. I frequently find it necessary to stand up for what I think is right. 3. I have at times stood in the way of people who were trying to do something, not because it amounted to much but because of the principle of the thing. 4. I like to let people know where I stand on things. 5. I am often so annoyed when someone trieds to get ahead of me in a line of people that I speak to that person about it. 6. I have at times had to be rough with people who were rude or annoying. 7. I am often inclined to go out of my way to win a point with someone who has opposed me. 8. I am usually very direct with people I am trying to correct or improve. 9. I do not try to cover up my poor opinion or pity of people so that they won’t know how I feel. 10. I strongly defend my opinions as a rule. 11. When people do something that makes me angry, I let them know how I feel about it. 12. I like to drive a hard bargain. 13. I like making decisions and assigning jobs to others.
*True ⫽ 1; false ⫽ 0. Range of possible scores: 0 to 13.
APPENDIX B
MMPI-2 Factor Analytically Derived Anger Scale Items:† 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.
At times I feel like swearing. At times I feel like smashing things. I have very few quarrels with members of my family (reverse). Sometimes when I am not feeling well, I am irritable. Often I cannot understand why I have been so irritable and grouchy. It makes me impatient to have people ask my advice or otherwise interrupt me when I am working on something important. I get mad easily and then get over it soon. I easily become impatient with people. I am not easily angered (reverse). I get angry when my friends or family give me advice on how to live my life. I am often said to be hot headed. I am often sorry because I am so irritable and grouchy. I often become very irritable when people interrupt my work. Sometimes I get so angry and upset, I do not know what comes over me. I have become so angry with someone that I have felt as if I would explode (or reverse). I almost never lose self-control (reverse).
True ⫽ 1; false ⫽ 0. Range of possible scores: 0 to 16.
†
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