American Journal of Epidemiology Copyright C 1992 by The Johns Hopkins Urcverstty School of Hygiene and Public Hearth All rights reserved
Vol. 136, No 2 Printed in U.S.A.
ORIGINAL CONTRIBUTIONS Hostility and Health Behaviors in Young Adults: The CARDIA Study
Larry W. Scherwitz,1 Laura L Perkins,2 Margaret A. Chesrtey,1 Glenn H. Hughes,3 Stephen Sidney,4 and Teri A. Manolio5
Hostility has been associated with coronary heart disease mortality. To assess possible mechanisms linking hostility to coronary heart disease risk, the authors conducted analyses in a cross-sectional study from data collected in 1985 and 1986 on 5,115 young adults, aged 18-30 years, black and white, male and female, in four large urban areas of the United States. The results show that higher levels of hostility as determined by the Cook-Medley Hostility Scale were strongly associated with tobacco and marijuana smoking, increased alcohol consumption, and greater caloric intake in both blacks and whites and in both men and women. The increased caloric consumption was evident in the higher waist/hip ratios, particularly in men (p < 0.05). The associations were particularly strong (p < 0.001) for tobacco cigarette smoking and marijuana smoking, with roughly a 1.5 times higher prevalence in the top hostility quartile compared with the bottom quartile after adjusting for age and education. Hostility levels were not related to the percentage of calories from fat or from sucrose intake, to plasma cholesterol levels, or to physical fitness (except for a weak association in the latter in white women). The results describe relations between hostility and health behaviors that may be detrimental to health. The findings provide a possible explanation for the association between hostility and coronary heart disease mortality. Am J Epidemiol 1992;136:136-45. alcohol drinking; body mass index; coronary disease; exercise; health behavior; hostility; mortality; smoking
Prospective epidemiologic studies have identified hostility as a risk factor for coronary heart disease incidence and all-cause mortality, as well as a correlate of angiographically determined coronary artery disease severity (1-4). The instrument used to measure hostility in these studies is the 50-
item Cook-Medley Hostility Scale derived from the Minnesota Multiphasic Personality Inventory (5). This scale is believed to be primarily a measure of cynicism and resentment rather than overt aggression (6-8). Not all studies have found a relation between Cook-Medley hostility and coronary
Received for publication April 25, 1991, and in final form September 16, 1991. Abbreviations: CARDIA, Coronary Artery Risk Development in Young Adults; UNCAHS, University of North Carolina Alumni Heart Study. 1 University of California, San Francisco, San Francisco, CA. 2 University of Alabama, Birmingham, AL. 3 West Alabama Health Services, Inc., Eutaw, AL. 4 Kaiser Permanente, Oakland, CA. 5 National Heart, Lung, and Blood Institute, Bethesda,
MD. Reprint requests to Stephen Sparler, 23 Woodland Ave , San Francisco, CA 94117. This study was supported by contracts N01 -HC-48047, N01-HC-48048, N01-HC-48049, N01-HC-48050, N01-HC95095, and HL-29573 from the National Heart, Lung, and Blood Institute, National Institutes of Health. The authors acknowledge the helpful comments on this paper by Dr. David Jacobs, Dr. Lynn Wagenkneckt, Dr Dene Siegter, Dr. Redford Williams, and Dr. John Barefoot.
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Hostility and Coronary Risk heart disease incidence, all-cause mortality (9-11), or angiographically determined coronary artery disease (12, 13). While methodological problems may partially explain these negative findings (14), further research is needed to resolve these inconsistencies and to identify the pathways by which hostility may be associated with increased mortality risk. The objective of this paper is to explore relations between hostility and behaviors that may increase the risk for coronary heart disease and all-cause mortality. Previous studies have shown the Cook-Medley Hostility Scale to be related to potentially detrimental behaviors. Leiker and Hailey (15) found that cynically hostile individuals tended to drink more alcohol, and Shekelle (2) found that cynically hostile individuals tended to smoke more cigarettes. Most recently, Houston and Vavak (16) found that cynically hostile college students tended to drink more alcohol and had a higher relative weight, but they did not differ in exercise or food preference from their low-hostility counterparts. The populations of these studies are rather restricted in terms of race and education, and the measures of health behaviors are based upon self-report questionnaires. A more definitive examination of the relation between hostility and coronary heart disease is needed. The Coronary Artery Risk Development in Young Adults (CARDIA) Study, presented in this paper, and the University of North Carolina Alumni Heart Study (UNCAHS), presented in the companion paper that follows by Siegler et al. (17), provide a useful means to more definitively evaluate one mechanism whereby hostility may be associated with coronary heart disease and all-cause mortality: the link between hostility and detrimental health behaviors. Both studies use the CookMedley measure of hostility and some similar measures of health behaviors. A weakness of each study is complemented by the strength of the other. The UNCAHS is restricted in terms of education and race. The CARDIA Study population is fairly evenly balanced by sex, race, and education. How-
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ever, the CARDIA Study does not yet have long-term follow-up results. The UNCAHS has baseline and 23-year follow-up data that allow the comparison of cross-sectional with prospective results. Together, the studies extend the generalizability as well as the prospective validity of the findings. MATERIALS AND METHODS Population
The CARDIA Study is a prospective epidemiologic study investigating the distribution, antecedents, and progression of risk factors for the development of atherosclerotic cardiovascular disease. The study design, recruitment of participants, and selected baseline descriptive findings are reported elsewhere (18). Four clinical centers located in Birmingham, Alabama, Chicago, Illinois, Minneapolis, Minnesota, and Oakland, California, recruited 5,115 individuals over a 16-month period in 1985 and 1986. In each center, participants were recruited by telephone or door-to-door from the total community or from selected census tracts, except in Oakland where a health plan membership roster was used. The sample was approximately balanced within each center on age (18-24 years, 25-30 years), sex, race (white, black), and level of education (high school or less, more than high school). Exclusion criteria included those with physical handicaps, those with the inability to communicate, and those who were pregnant. Twenty-three percent of the individuals originally contacted made appointments but did not show up for the examination, 20 percent refused the invitation to participate, 3 percent were ineligible, and 4 percent had incomplete interviews. This left 50 percent of the individuals contacted who were actually examined (5,115 of 10,143). Participation was higher among contacted whites than blacks (60 percent vs. 47 percent) and was higher among those who had more than a high school education than among those with a high school education or less (58 percent vs. 46 percent). Risk factor data are available only for smoking; 30.8 percent of the participants smoked cigarettes, com-
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pared with 34.2 percent of the nonparticipants. Each subject was given an explanation of medical examinations and psychosocial questionnaires and signed an informed consent document with an indication, if he or she so desired, of physicians or health care facilities to which the medical results should be sent. Data collection instruments
The instrument used to measure hostility was the 50-item Cook-Medley subscale of the Minnesota Multiphasic Personality Inventory (5). The theoretical range for an individual hostility score is 0-50, with higher scores indicating greater levels of cynical hostility. Sample items from the CookMedley Hostility Scale are the following: "When I take a new job, I like to be tipped off on who should be gotten next to," and "When someone does me a wrong I feel I should pay him back if I can, just for the principle of the thing." The mean hostility scores for race, sex, age, and education for this sample and comparative hostility scores from other samples are presented in an earlier paper (19). Briefly, the overall mean hostility for all 5,115 subjects was 19.6, with the subgroup of black men having the highest mean level (23.6), followed by black women (20.9), white men (18.1), and white women (16.5). Cigarette smoking was measured by an interviewer-administered questionnaire with "ever smokers" defined as those who answered, "Yes," to the question about whether they had ever smoked cigarettes regularly for at least 3 months, and "current smokers" were defined as smoking at least five cigarettes per week, almost every week, for at least 3 months. Smoking status was confirmed by serum cotinine assays with 93 percent (1,419 of 1,527) of the smokers and 96 percent (3,351 of 3,507) of the nonsmokers correctly classified using a cutoff point of 19 ng/ml to define smoking (20). Marijuana use was measured by a selfadministered questionnaire that asked if subjects had ever used marijuana and, if so,
the frequency and quantity of use in the past 30 days. Current use was defined as use within the past 30 days. Alcohol intake was measured by an interviewer-administered questionnaire assessing consumption during the past year and the average number of drinks of beer, wine, and liquor usually consumed in a week, where 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of liquor were each considered to be one drink. Alcohol consumption per week was calculated using the following formula: ml/week = beers x 16.7 + wines x 17.02 + liquors x 19.09(21). Dietary data were collected by a nutritionist-administered dietary history interview developed especially for the CARDIA Study (22). This instrument measured diet based on the previous month's food intake and was modeled after the diet history used in the Western Electric Study (23,24). Nutrient data were analyzed by the CARDIA Study Coordinating Center in Birmingham using the data base (tape 10) of the Nutrition Coordinating Center of Minneapolis (25). Total fat, saturated fat, sucrose, and caffeine were adjusted for caloric intake (percent kilocalories) in analyses in this paper. Venous blood was collected following a 12-hour fast (91 percent of the participants were fasting). Total cholesterol was determined, using enzymatic procedures, by the University of Washington Northwest Lipid Research Clinic Laboratory (26). Highdensity-lipoprotein cholesterol was measured by enzymatic methods after dextran sulfate-magnesium precipitation (27-29). For individuals with triglyceride levels less than 400 mg/dl, low-density-lipoprotein cholesterol was estimated using the Friedewald equation (30). We have used both body mass index and waist/nip ratio as measures of weight. Body mass index was calculated as weight (kg)/ height (m)2 (31). The waist/hip ratio was used as a measure of truncal obesity, and it has been positively related to ischemic heart disease (32-34), stroke (35), diabetes (36), hypertension (37) and, most recently, alcohol consumption and cigarette smoking (38).
Hostility and Coronary Risk
Waist circumference was measured under clothing at the minimal abdominal girth, in duplicate, to the nearest half centimeter. Hip circumference was measured over light clothing at the maximal protrusion of the buttocks, in duplicate, to the nearest half centimeter. The average of the two measurements of each circumference was used in the analysis. The waist/hip ratio was calculated by dividing the average waist girth by the average hip girth. After a 5-minute rest, blood pressure was measured three times at 1-minute intervals using a Hawksley random-zero sphygmomanometer, the first and fifth phase Korotkoff sounds were recorded. Analyses in this paper used the average of the second and third readings. Participants were classified as having hypertension if their diastolic blood pressure was 90 mmHg or higher or if their systolic blood pressure was 140 mmHg or higher or if the participant was taking antihypertensive medication. Leisure time physical activity was assessed using the questionnaire developed for the CARDIA Study and based on the Minnesota Leisure Time Activity (39) and the Stanford Heart Disease Prevention Program questionnaires (40). Physical fitness was assessed as the time taken to reach a heart rate of 130 beats per minute on a graded treadmill exercise test. Statistical analyses
Within each race-sex subgroup, linear regression analyses were used to model health behaviors or risk factors (measured as continuous variables, for example, ml of alcohol) as a function of hostility, age, number of years of education, and all two-way and three-way interactions. Significant interactions were not reported because of their relatively small impact on the main effects. The model for total calories included physical activity level, body mass index, smoking status, age, and education. The model for cholesterol, high-density lipoprotein, and low-density lipoprotein included physical activity level, body mass index, and alcohol (ml). Logistic regression models similar to
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the linear regression models were used for dichotomous outcomes (for example, current smoking). To perform a test for trend in the logistic models, hostility was categorized using race- and sex-specific quartiles. In tables 1 and 2 and figures 1-3, means and proportions are presented for the race- and sex-specific quartiles of hostility adjusting for age, number of years of education, and any other covariates and interactions included in the model. All regression analyses used hostility as a continuous dependent variable, but for presentation in the tables we used race-sex quartiles, so that one could quantify how much health behaviors differed by hostility levels. Because of the large sample size and therefore the ability to detect weak associations, a level of 0.01 was used to determine statistical significance. RESULTS
The prevalence of cigarette smoking varied from 21 percent for black women to 38 percent for black men. Prevalence of cigarette smoking was approximately 1.5 times higher in the highest hostility compared with the lowest hostility quartile; this was statistically significant in all race-sex groups (figure 1). However, the average number of cigarettes smoked per day (18.2 for white men, 14.6 for white women, 10.9 for black men, and 10.7 for black women) was not associated with hostility level. Though in this study blacks smoked stronger cigarettes than did whites, a reanalysis correcting for the nicotine level by brand of cigarette also showed no relation of hostility to nicotine intake. In each race-sex group except black men, prevalence of current marijuana use (use within the last 30 days) was positively associated with hostility, with those in the highest hostility quartile approximately 1.5 times as likely to be marijuana users than those in the lowest hostility quartile (see figure 2). Hostility was associated with the number of days that marijuana was used in the past month in both white men and black women (p = 0.005 and p = 0.009, respectively). The percentage of subjects reporting al-
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Scherwitzetal.
Black Men
White Men
Black Women White Women
Sex-Gender FIGURE 1. Percentage of cigarette smokers by Cook-Medley Hostility Scale quartile, race, and sex: CARDIA Study, 1985-1986. Hostility: D, low; • , moderate; U, high; • , very high.
50 r-
i _ ..u.
Black Men
White Men
Black Women White Women
Sex-Gender RGURE 2. Percentage of current marijuana users by Cook-Medley Hostility Scale quartile, race, and sex: CARDIA Study, 1985-1986. Hostility: D, low; • , moderate; • , high; • , very high.
cohol consumption in the past year ranged from 78 percent in black women to 92 percent in white men and was not related to hostility in any race-sex group. However, among drinkers, the average weekly alcohol intake increased significantly with hostility (p < 0.0001) (figure 3). The increase in alcohol consumption between the lowest and highest hostility quartiles was approximately 8 ml/week in both black men and white men compared with 4.6 ml/week and 6.9 ml/week in black women and white women, respectively.
The estimated caloric intake increased significantly with hostility in each race-sex group (p < 0.0001) (table 1). Black men in the highest hostility quartile consumed an average of 628 calories per day more than did black men in the lowest hostility quartile. For black women, this difference was 490 calories compared with 594 calories for white men and 295 calories for white women. The percentages of calories from fat, saturated fat, and sucrose were not associated with hostility level in any race-sex group
Hostility and Coronary Risk
Black Men
White Men
Black Women
141
White Women
Sex-Gender
FIGURE 3. Alcohol consumption (ml/week) by Cook-Medley Hostility Scale quartile for race and sex groups: CARDIA Study, 1985-1986. Hostility: D, low; • , moderate; • , high; • , very high.
(p > 0.05, data not presented). Caffeine intake (mg/1,000 calories) did not differ by hostility level except in black women, in whom caffeine intake decreased with increasing level of hostility (table 1). This decline in caffeine intake with hostility was primarily due to a negative relation between caffeine intake and hostility in older women. There were no significant differences by hostility quartile in the reported activity level or in the time to reach a heart rate of 130 on the treadmill in men or in black women (table 2). Among white women, hostility was not significantly positively associated with physical activity (p = 0.02); nevertheless, the trend is consistent with the significant positive association between hostility and time to reach a heart rate of 130 on the treadmill (p = 0.002). There were no significant differences by hostility quartile in body mass index, total cholesterol, and high-density-lipoprotein or low-density-lipoprotein cholesterol. However, hostility was positively correlated with waist/hip ratio for each of the four race-sex subgroups. After adjusting for current smoking, total calories, and physical activity, we found that the relation of hostility with waist/hip ratio remained significant in black men (p = 0.01) and marginally significant in white men (p = 0.02). For both black
men and white men, a change in hostility score of 20 was associated with a predicted mean change of 0.008 in the waist/hip ratio, reflecting a small but statistically significant change (multiple linear regression, R2 = 0.124 for black men, R2 = 0.083 for white men). Contrary to expectations, there was a weak negative relation between hostility and blood pressure levels, which reached significance for systolic blood pressure in white females (p = 0.01) and for diastolic blood pressure in black females (p = 0.006). There were very few subjects classified as hypertensive in any race-sex group (4.9 percent of black men, 3.6 percent of white men, 2.8 percent of black women, and 1.1 percent of white women; 3.0 percent in all), and except for black men (p = 0.04), there were no significant associations of hostility with hypertension (white men, p = 0.8; white women, p = 0.9; black women, p = 0.69). DISCUSSION
The major finding is that the CookMedley Hostility Scale is associated with a pattern of consumptive health behaviors, some of which have been found to be associated with coronary heart disease and other health problems. The more hostile young adults are more likely to smoke cigarettes
0.0001
0.0001
± 48.9 ±45.6 ±52.2 ± 52.0
0.154
1,976 2,165 2,156 2,271 2,136 ± 24.5
± 11.5 ±11.5 ±11.9 ±12.2
Calories/day
133.8 ±5.8
121.8 129.4 137.9 152.1
Caffeine intake ±16.5 ±15.4 ±17.6 ±17.4
0.202
194.3 ±8.2
189.5 188.5 191.9 207.6
Caffeine intake
White women (n = 1,306)
4.5 4.5 4.9 4.7
0.605
± ± ± ±
0.0004
42.7 33.4 40.8 42.2 39.4 ± 2.3
±136.4 ± 135.7 ±147.8 ±141.5
Caffeine Intake
4,040 ±71.3
3,740 3,897 4,196 4,368
Calories/day
Black men (0 = 1,157)
± 66.9 ± 70.2 ±70.0 ± 74.5
0.0001
2,590 ± 35.5
2,361 2,576 2,619 2,851
Calories/day ± 6.5 ±6.9 ± 6.8 ± 7.2
0.005
63.5 ± 3.3
68.7 71.2 57.3 58.1
Caffeine intake
Black women (n - 1,477)
± ± ± ±
6.6 6.7 6.9 7.1
0.448
351.6 ±3.3
346.2 350.0 347.8 355.6
Trne to HR130 ±14.3 ±13.3 ±15.3 ±15.0
0.017
400 ± 7.2
387 369 419 428
Physical activity ±5.6 ±5.2 ± 5.9 ± 5.9
0.002
220.9 ± 2.8
212.2 218.6 217.1 236.2
Time to HR130
White women (n = 1,259)
± 20.2 ± 20.2 ±21.9 ±21.0
0.516
535 ±10.1
526 535 571 506
Physical activity
7.1 7.0 7.7 7.6
0.265
353.5 ± 3.6
± ± ± ±
Time to HR130 356.6 359.9 349.5 344.4
Black men (n-1,097)
± 11.6 ± 12.2 ±12.2 ±12.9
0.129
278 ± 5.9
288 283 275 267
Physical activity
±4.2 ±4.4 ±4.4 ±4.7
0.118
182.3 ± 2 . 2
180.7 177.4 184.3 190.2
Time to HR130
Black women (n = 1,392)
* Least-square means adjusting for age, education, and body mass index; nonsignificant Interactions dropped. f Least-square means adjusting for age, education, and smoking; nonsignificant interactions dropped. % Mean ± standard error. 5 p values based on regression models using the Ho scale as a continuous measure and adjusting for covartates In the above footnotes; nonsignificant interactions dropped.
0.090
510 ±8.8
Total
p value§
506 ±17.8 490 ±18.3 510 ±18.8
Physical activity
White men (n = 1,139)
Low Moderate High Very high
Hostility level
TABLE 2. Reported physical activity* and time taken to reach a heart rate of 130 (HR130)t on treadmill by Cook-Medley hostility level, race, and sex: The CARDIA Study, 1985-1986
* Mean calories are based on least-square means adjusted for age, education, body mass Index, physical activity, and cigarette smoking status; nonsignificant Interactions dropped, t Caffeine Intake Is expressed as mg/day x 1,000 cflvided by total daily caloric intake; caffeine means based upon least-square means adjusted for age and education; nonsignfflcant Interactions dropped. t Mean ± standard error. § p values based on regression models using the Ho scale as a continuous measure and adjusting for covartates In the above footnotes; nonsignificant interactions dropped.
p value§
3,292 ±41.8
Total
77.6$ 78.1 80.5 82.7
2,954 ± 3,292 ± 3,473 ± 3,548 ±
Calories/day
White men (n = 1,171)
Low Moderate High Very high
Hostfflty
TABLE 1. Total daily calories* and caffeine intakef by Cook-Medley hostility level, race, and sex: The CARDIA Study, 1985-1986
CD
tn o
Hostility and Coronary Risk and to smoke marijuana, they consume more calories than their low-hostility counterparts, and they drink more alcohol, a finding consistent with two other studies using the Cook-Medley Hostility Scale (16, 17). While 50 percent of those contacted were examined, we cannot be certain that these results generalize to the population contacted. The nonparticipants had a higher smoking rate than did the participants, and they also may have had a stronger association between hostility and health behaviors. Thus, we regard the findings as a possible conservative estimate of the relation of hostility to health behaviors. Nevertheless, the magnitude of the differences and the consistency of the findings suggest that hostility may underlie a clustering of risk factors. These different risk behaviors may work in concert to increase coronary heart disease risk and probably account for some of the previously reported relations between hostility and total mortality. However, not all the behaviors have been found to be detrimental. For example, few studies have looked at whether marijuana use is associated with coronary heart disease. Moderate alcohol consumption is associated with less coronary heart disease incidence; however, with increased alcohol consumption, there are more accidents, cancer, and cerebrovascular deaths (41). The consistency of the relations between hostility level and cigarette smoking, alcohol intake, and caloric intake across race, sex, age, and education increases the confidence in generalizing these findings to other young adults. However, not all the variables we measured are positively related to hostility. Even though those with more hostility consume many more calories, the percentage of calories from either saturated fat, unsaturated fat, or sucrose does not differ by hostility level. This is consistent with the results of Houston and Vavak (16), who found that choices of foods containing high sodium, cholesterol, or saturated fat did not differ between high- and low-hostility students. Contrary to the pattern found with alcohol and marijuana use, the hostility level was not related to number of cigarettes smoked
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per day, a finding consistent with that of Houston and Vavak (16) who also found the number of cigarettes smoked not to differ between high- and low-hostility college students. Except for white women, caffeine consumption was slightly less for the higher levels of hostility. Even though high-hostility subjects are likely to smoke more, to use more marijuana, to drink more alcohol, and to consume more calories than low-hostility individuals, they may have just begun to suffer the ill effects of these behaviors. Their waist/ hip ratio, which is related to increased stress hormones and mortality (42), is a little higher than that of their lower hostile counterparts. Nevertheless, serum cholesterol, reported physical exercise, exercise time on the treadmill, and blood pressure show no ill effects from cigarette, alcohol, and caloric consumption. However, the companion paper by Siegler et al. (17) presents prospective evidence that hostility measured at baseline is related to a higher body mass, a poorer lipid profile, and a greater likelihood of having a diagnosis of hypertension 20 years later. Perhaps it takes time for hostility to have an impact on physiologic risk factors. It is not clear from our cross-sectional findings whether increased alcohol, cigarette, and marijuana use and increased caloric intake make one more hostile; whether hostile individuals cope with their negative experiences by consuming more substances; or whether a third factor is related to both hostility and health behaviors. However, the prospective findings of Siegler et al. (17) relating baseline hostility level with higher body mass index, lipid ratio, and higher percentage of cigarette smokers 23 years later strengthen the interpretation that hostility is causally related to health behaviors. In a previous paper from the CARDIA Study sample, the hostile individuals reported more negative life events and less social support (19), a finding also reported by others (7, 43). With greater stress and less social support to buffer the effects of stress, the more hostile individuals may have coped with stress by consuming excess food, cigarettes, or marijuana.
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In summary, the results link hostility with tobacco and marijuana use, alcohol consumption, waist/hip ratio, and caloric intake and therefore provide a possible explanation for the association between hostility and mortality. If hostility contributes to these health behaviors, it may impede intervention efforts to change these behaviors.
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located body fat and the effect of race and sex on this risk. Am J Epidemiol 1984;119:526-40. Laws A, Terry RB, Barrett-Connor E. Behavioral covariates of waist-to-hip ratio in Rancho Bernardo. Am J Public Health 199O;80:1358-62. Jacobs DR, Hahn LP, Haskell WL, et al. Validity and reliability of short physical activity history: CARDIA and the Minnesota Heart Health Program. J Cardiopul Rehab l989;9:448-59. Sallis JF, Haskell WL, Wood PD, et al. Physical activity assessment methodology in the Five-City Project Am J Epidemiol 1985; 121:91-106. Ellison RC. Cheers. Epidemiology 1990; 1:337-9. Rodin J. Where fat is at: some surprising new consequences of stress, dieting, and substance abuse. Presidential Address. Presented at the 12th annual scientific sessions of the Society of Behavioral Medicine, Washington, DC, March 1991. Hardy JD, Smith TW. Cynical hostility and vulnerability to disease: social support, life stress, and physiological response to conflict. Health Psychol 1988;7:447-59.
Vol. 136, No 2 Printed in U.S.A.
ORIGINAL CONTRIBUTIONS Hostility and Health Behaviors in Young Adults: The CARDIA Study
Larry W. Scherwitz,1 Laura L Perkins,2 Margaret A. Chesrtey,1 Glenn H. Hughes,3 Stephen Sidney,4 and Teri A. Manolio5
Hostility has been associated with coronary heart disease mortality. To assess possible mechanisms linking hostility to coronary heart disease risk, the authors conducted analyses in a cross-sectional study from data collected in 1985 and 1986 on 5,115 young adults, aged 18-30 years, black and white, male and female, in four large urban areas of the United States. The results show that higher levels of hostility as determined by the Cook-Medley Hostility Scale were strongly associated with tobacco and marijuana smoking, increased alcohol consumption, and greater caloric intake in both blacks and whites and in both men and women. The increased caloric consumption was evident in the higher waist/hip ratios, particularly in men (p < 0.05). The associations were particularly strong (p < 0.001) for tobacco cigarette smoking and marijuana smoking, with roughly a 1.5 times higher prevalence in the top hostility quartile compared with the bottom quartile after adjusting for age and education. Hostility levels were not related to the percentage of calories from fat or from sucrose intake, to plasma cholesterol levels, or to physical fitness (except for a weak association in the latter in white women). The results describe relations between hostility and health behaviors that may be detrimental to health. The findings provide a possible explanation for the association between hostility and coronary heart disease mortality. Am J Epidemiol 1992;136:136-45. alcohol drinking; body mass index; coronary disease; exercise; health behavior; hostility; mortality; smoking
Prospective epidemiologic studies have identified hostility as a risk factor for coronary heart disease incidence and all-cause mortality, as well as a correlate of angiographically determined coronary artery disease severity (1-4). The instrument used to measure hostility in these studies is the 50-
item Cook-Medley Hostility Scale derived from the Minnesota Multiphasic Personality Inventory (5). This scale is believed to be primarily a measure of cynicism and resentment rather than overt aggression (6-8). Not all studies have found a relation between Cook-Medley hostility and coronary
Received for publication April 25, 1991, and in final form September 16, 1991. Abbreviations: CARDIA, Coronary Artery Risk Development in Young Adults; UNCAHS, University of North Carolina Alumni Heart Study. 1 University of California, San Francisco, San Francisco, CA. 2 University of Alabama, Birmingham, AL. 3 West Alabama Health Services, Inc., Eutaw, AL. 4 Kaiser Permanente, Oakland, CA. 5 National Heart, Lung, and Blood Institute, Bethesda,
MD. Reprint requests to Stephen Sparler, 23 Woodland Ave , San Francisco, CA 94117. This study was supported by contracts N01 -HC-48047, N01-HC-48048, N01-HC-48049, N01-HC-48050, N01-HC95095, and HL-29573 from the National Heart, Lung, and Blood Institute, National Institutes of Health. The authors acknowledge the helpful comments on this paper by Dr. David Jacobs, Dr. Lynn Wagenkneckt, Dr Dene Siegter, Dr. Redford Williams, and Dr. John Barefoot.
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Hostility and Coronary Risk heart disease incidence, all-cause mortality (9-11), or angiographically determined coronary artery disease (12, 13). While methodological problems may partially explain these negative findings (14), further research is needed to resolve these inconsistencies and to identify the pathways by which hostility may be associated with increased mortality risk. The objective of this paper is to explore relations between hostility and behaviors that may increase the risk for coronary heart disease and all-cause mortality. Previous studies have shown the Cook-Medley Hostility Scale to be related to potentially detrimental behaviors. Leiker and Hailey (15) found that cynically hostile individuals tended to drink more alcohol, and Shekelle (2) found that cynically hostile individuals tended to smoke more cigarettes. Most recently, Houston and Vavak (16) found that cynically hostile college students tended to drink more alcohol and had a higher relative weight, but they did not differ in exercise or food preference from their low-hostility counterparts. The populations of these studies are rather restricted in terms of race and education, and the measures of health behaviors are based upon self-report questionnaires. A more definitive examination of the relation between hostility and coronary heart disease is needed. The Coronary Artery Risk Development in Young Adults (CARDIA) Study, presented in this paper, and the University of North Carolina Alumni Heart Study (UNCAHS), presented in the companion paper that follows by Siegler et al. (17), provide a useful means to more definitively evaluate one mechanism whereby hostility may be associated with coronary heart disease and all-cause mortality: the link between hostility and detrimental health behaviors. Both studies use the CookMedley measure of hostility and some similar measures of health behaviors. A weakness of each study is complemented by the strength of the other. The UNCAHS is restricted in terms of education and race. The CARDIA Study population is fairly evenly balanced by sex, race, and education. How-
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ever, the CARDIA Study does not yet have long-term follow-up results. The UNCAHS has baseline and 23-year follow-up data that allow the comparison of cross-sectional with prospective results. Together, the studies extend the generalizability as well as the prospective validity of the findings. MATERIALS AND METHODS Population
The CARDIA Study is a prospective epidemiologic study investigating the distribution, antecedents, and progression of risk factors for the development of atherosclerotic cardiovascular disease. The study design, recruitment of participants, and selected baseline descriptive findings are reported elsewhere (18). Four clinical centers located in Birmingham, Alabama, Chicago, Illinois, Minneapolis, Minnesota, and Oakland, California, recruited 5,115 individuals over a 16-month period in 1985 and 1986. In each center, participants were recruited by telephone or door-to-door from the total community or from selected census tracts, except in Oakland where a health plan membership roster was used. The sample was approximately balanced within each center on age (18-24 years, 25-30 years), sex, race (white, black), and level of education (high school or less, more than high school). Exclusion criteria included those with physical handicaps, those with the inability to communicate, and those who were pregnant. Twenty-three percent of the individuals originally contacted made appointments but did not show up for the examination, 20 percent refused the invitation to participate, 3 percent were ineligible, and 4 percent had incomplete interviews. This left 50 percent of the individuals contacted who were actually examined (5,115 of 10,143). Participation was higher among contacted whites than blacks (60 percent vs. 47 percent) and was higher among those who had more than a high school education than among those with a high school education or less (58 percent vs. 46 percent). Risk factor data are available only for smoking; 30.8 percent of the participants smoked cigarettes, com-
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pared with 34.2 percent of the nonparticipants. Each subject was given an explanation of medical examinations and psychosocial questionnaires and signed an informed consent document with an indication, if he or she so desired, of physicians or health care facilities to which the medical results should be sent. Data collection instruments
The instrument used to measure hostility was the 50-item Cook-Medley subscale of the Minnesota Multiphasic Personality Inventory (5). The theoretical range for an individual hostility score is 0-50, with higher scores indicating greater levels of cynical hostility. Sample items from the CookMedley Hostility Scale are the following: "When I take a new job, I like to be tipped off on who should be gotten next to," and "When someone does me a wrong I feel I should pay him back if I can, just for the principle of the thing." The mean hostility scores for race, sex, age, and education for this sample and comparative hostility scores from other samples are presented in an earlier paper (19). Briefly, the overall mean hostility for all 5,115 subjects was 19.6, with the subgroup of black men having the highest mean level (23.6), followed by black women (20.9), white men (18.1), and white women (16.5). Cigarette smoking was measured by an interviewer-administered questionnaire with "ever smokers" defined as those who answered, "Yes," to the question about whether they had ever smoked cigarettes regularly for at least 3 months, and "current smokers" were defined as smoking at least five cigarettes per week, almost every week, for at least 3 months. Smoking status was confirmed by serum cotinine assays with 93 percent (1,419 of 1,527) of the smokers and 96 percent (3,351 of 3,507) of the nonsmokers correctly classified using a cutoff point of 19 ng/ml to define smoking (20). Marijuana use was measured by a selfadministered questionnaire that asked if subjects had ever used marijuana and, if so,
the frequency and quantity of use in the past 30 days. Current use was defined as use within the past 30 days. Alcohol intake was measured by an interviewer-administered questionnaire assessing consumption during the past year and the average number of drinks of beer, wine, and liquor usually consumed in a week, where 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of liquor were each considered to be one drink. Alcohol consumption per week was calculated using the following formula: ml/week = beers x 16.7 + wines x 17.02 + liquors x 19.09(21). Dietary data were collected by a nutritionist-administered dietary history interview developed especially for the CARDIA Study (22). This instrument measured diet based on the previous month's food intake and was modeled after the diet history used in the Western Electric Study (23,24). Nutrient data were analyzed by the CARDIA Study Coordinating Center in Birmingham using the data base (tape 10) of the Nutrition Coordinating Center of Minneapolis (25). Total fat, saturated fat, sucrose, and caffeine were adjusted for caloric intake (percent kilocalories) in analyses in this paper. Venous blood was collected following a 12-hour fast (91 percent of the participants were fasting). Total cholesterol was determined, using enzymatic procedures, by the University of Washington Northwest Lipid Research Clinic Laboratory (26). Highdensity-lipoprotein cholesterol was measured by enzymatic methods after dextran sulfate-magnesium precipitation (27-29). For individuals with triglyceride levels less than 400 mg/dl, low-density-lipoprotein cholesterol was estimated using the Friedewald equation (30). We have used both body mass index and waist/nip ratio as measures of weight. Body mass index was calculated as weight (kg)/ height (m)2 (31). The waist/hip ratio was used as a measure of truncal obesity, and it has been positively related to ischemic heart disease (32-34), stroke (35), diabetes (36), hypertension (37) and, most recently, alcohol consumption and cigarette smoking (38).
Hostility and Coronary Risk
Waist circumference was measured under clothing at the minimal abdominal girth, in duplicate, to the nearest half centimeter. Hip circumference was measured over light clothing at the maximal protrusion of the buttocks, in duplicate, to the nearest half centimeter. The average of the two measurements of each circumference was used in the analysis. The waist/hip ratio was calculated by dividing the average waist girth by the average hip girth. After a 5-minute rest, blood pressure was measured three times at 1-minute intervals using a Hawksley random-zero sphygmomanometer, the first and fifth phase Korotkoff sounds were recorded. Analyses in this paper used the average of the second and third readings. Participants were classified as having hypertension if their diastolic blood pressure was 90 mmHg or higher or if their systolic blood pressure was 140 mmHg or higher or if the participant was taking antihypertensive medication. Leisure time physical activity was assessed using the questionnaire developed for the CARDIA Study and based on the Minnesota Leisure Time Activity (39) and the Stanford Heart Disease Prevention Program questionnaires (40). Physical fitness was assessed as the time taken to reach a heart rate of 130 beats per minute on a graded treadmill exercise test. Statistical analyses
Within each race-sex subgroup, linear regression analyses were used to model health behaviors or risk factors (measured as continuous variables, for example, ml of alcohol) as a function of hostility, age, number of years of education, and all two-way and three-way interactions. Significant interactions were not reported because of their relatively small impact on the main effects. The model for total calories included physical activity level, body mass index, smoking status, age, and education. The model for cholesterol, high-density lipoprotein, and low-density lipoprotein included physical activity level, body mass index, and alcohol (ml). Logistic regression models similar to
139
the linear regression models were used for dichotomous outcomes (for example, current smoking). To perform a test for trend in the logistic models, hostility was categorized using race- and sex-specific quartiles. In tables 1 and 2 and figures 1-3, means and proportions are presented for the race- and sex-specific quartiles of hostility adjusting for age, number of years of education, and any other covariates and interactions included in the model. All regression analyses used hostility as a continuous dependent variable, but for presentation in the tables we used race-sex quartiles, so that one could quantify how much health behaviors differed by hostility levels. Because of the large sample size and therefore the ability to detect weak associations, a level of 0.01 was used to determine statistical significance. RESULTS
The prevalence of cigarette smoking varied from 21 percent for black women to 38 percent for black men. Prevalence of cigarette smoking was approximately 1.5 times higher in the highest hostility compared with the lowest hostility quartile; this was statistically significant in all race-sex groups (figure 1). However, the average number of cigarettes smoked per day (18.2 for white men, 14.6 for white women, 10.9 for black men, and 10.7 for black women) was not associated with hostility level. Though in this study blacks smoked stronger cigarettes than did whites, a reanalysis correcting for the nicotine level by brand of cigarette also showed no relation of hostility to nicotine intake. In each race-sex group except black men, prevalence of current marijuana use (use within the last 30 days) was positively associated with hostility, with those in the highest hostility quartile approximately 1.5 times as likely to be marijuana users than those in the lowest hostility quartile (see figure 2). Hostility was associated with the number of days that marijuana was used in the past month in both white men and black women (p = 0.005 and p = 0.009, respectively). The percentage of subjects reporting al-
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Scherwitzetal.
Black Men
White Men
Black Women White Women
Sex-Gender FIGURE 1. Percentage of cigarette smokers by Cook-Medley Hostility Scale quartile, race, and sex: CARDIA Study, 1985-1986. Hostility: D, low; • , moderate; U, high; • , very high.
50 r-
i _ ..u.
Black Men
White Men
Black Women White Women
Sex-Gender RGURE 2. Percentage of current marijuana users by Cook-Medley Hostility Scale quartile, race, and sex: CARDIA Study, 1985-1986. Hostility: D, low; • , moderate; • , high; • , very high.
cohol consumption in the past year ranged from 78 percent in black women to 92 percent in white men and was not related to hostility in any race-sex group. However, among drinkers, the average weekly alcohol intake increased significantly with hostility (p < 0.0001) (figure 3). The increase in alcohol consumption between the lowest and highest hostility quartiles was approximately 8 ml/week in both black men and white men compared with 4.6 ml/week and 6.9 ml/week in black women and white women, respectively.
The estimated caloric intake increased significantly with hostility in each race-sex group (p < 0.0001) (table 1). Black men in the highest hostility quartile consumed an average of 628 calories per day more than did black men in the lowest hostility quartile. For black women, this difference was 490 calories compared with 594 calories for white men and 295 calories for white women. The percentages of calories from fat, saturated fat, and sucrose were not associated with hostility level in any race-sex group
Hostility and Coronary Risk
Black Men
White Men
Black Women
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White Women
Sex-Gender
FIGURE 3. Alcohol consumption (ml/week) by Cook-Medley Hostility Scale quartile for race and sex groups: CARDIA Study, 1985-1986. Hostility: D, low; • , moderate; • , high; • , very high.
(p > 0.05, data not presented). Caffeine intake (mg/1,000 calories) did not differ by hostility level except in black women, in whom caffeine intake decreased with increasing level of hostility (table 1). This decline in caffeine intake with hostility was primarily due to a negative relation between caffeine intake and hostility in older women. There were no significant differences by hostility quartile in the reported activity level or in the time to reach a heart rate of 130 on the treadmill in men or in black women (table 2). Among white women, hostility was not significantly positively associated with physical activity (p = 0.02); nevertheless, the trend is consistent with the significant positive association between hostility and time to reach a heart rate of 130 on the treadmill (p = 0.002). There were no significant differences by hostility quartile in body mass index, total cholesterol, and high-density-lipoprotein or low-density-lipoprotein cholesterol. However, hostility was positively correlated with waist/hip ratio for each of the four race-sex subgroups. After adjusting for current smoking, total calories, and physical activity, we found that the relation of hostility with waist/hip ratio remained significant in black men (p = 0.01) and marginally significant in white men (p = 0.02). For both black
men and white men, a change in hostility score of 20 was associated with a predicted mean change of 0.008 in the waist/hip ratio, reflecting a small but statistically significant change (multiple linear regression, R2 = 0.124 for black men, R2 = 0.083 for white men). Contrary to expectations, there was a weak negative relation between hostility and blood pressure levels, which reached significance for systolic blood pressure in white females (p = 0.01) and for diastolic blood pressure in black females (p = 0.006). There were very few subjects classified as hypertensive in any race-sex group (4.9 percent of black men, 3.6 percent of white men, 2.8 percent of black women, and 1.1 percent of white women; 3.0 percent in all), and except for black men (p = 0.04), there were no significant associations of hostility with hypertension (white men, p = 0.8; white women, p = 0.9; black women, p = 0.69). DISCUSSION
The major finding is that the CookMedley Hostility Scale is associated with a pattern of consumptive health behaviors, some of which have been found to be associated with coronary heart disease and other health problems. The more hostile young adults are more likely to smoke cigarettes
0.0001
0.0001
± 48.9 ±45.6 ±52.2 ± 52.0
0.154
1,976 2,165 2,156 2,271 2,136 ± 24.5
± 11.5 ±11.5 ±11.9 ±12.2
Calories/day
133.8 ±5.8
121.8 129.4 137.9 152.1
Caffeine intake ±16.5 ±15.4 ±17.6 ±17.4
0.202
194.3 ±8.2
189.5 188.5 191.9 207.6
Caffeine intake
White women (n = 1,306)
4.5 4.5 4.9 4.7
0.605
± ± ± ±
0.0004
42.7 33.4 40.8 42.2 39.4 ± 2.3
±136.4 ± 135.7 ±147.8 ±141.5
Caffeine Intake
4,040 ±71.3
3,740 3,897 4,196 4,368
Calories/day
Black men (0 = 1,157)
± 66.9 ± 70.2 ±70.0 ± 74.5
0.0001
2,590 ± 35.5
2,361 2,576 2,619 2,851
Calories/day ± 6.5 ±6.9 ± 6.8 ± 7.2
0.005
63.5 ± 3.3
68.7 71.2 57.3 58.1
Caffeine intake
Black women (n - 1,477)
± ± ± ±
6.6 6.7 6.9 7.1
0.448
351.6 ±3.3
346.2 350.0 347.8 355.6
Trne to HR130 ±14.3 ±13.3 ±15.3 ±15.0
0.017
400 ± 7.2
387 369 419 428
Physical activity ±5.6 ±5.2 ± 5.9 ± 5.9
0.002
220.9 ± 2.8
212.2 218.6 217.1 236.2
Time to HR130
White women (n = 1,259)
± 20.2 ± 20.2 ±21.9 ±21.0
0.516
535 ±10.1
526 535 571 506
Physical activity
7.1 7.0 7.7 7.6
0.265
353.5 ± 3.6
± ± ± ±
Time to HR130 356.6 359.9 349.5 344.4
Black men (n-1,097)
± 11.6 ± 12.2 ±12.2 ±12.9
0.129
278 ± 5.9
288 283 275 267
Physical activity
±4.2 ±4.4 ±4.4 ±4.7
0.118
182.3 ± 2 . 2
180.7 177.4 184.3 190.2
Time to HR130
Black women (n = 1,392)
* Least-square means adjusting for age, education, and body mass index; nonsignificant Interactions dropped. f Least-square means adjusting for age, education, and smoking; nonsignificant interactions dropped. % Mean ± standard error. 5 p values based on regression models using the Ho scale as a continuous measure and adjusting for covartates In the above footnotes; nonsignificant interactions dropped.
0.090
510 ±8.8
Total
p value§
506 ±17.8 490 ±18.3 510 ±18.8
Physical activity
White men (n = 1,139)
Low Moderate High Very high
Hostility level
TABLE 2. Reported physical activity* and time taken to reach a heart rate of 130 (HR130)t on treadmill by Cook-Medley hostility level, race, and sex: The CARDIA Study, 1985-1986
* Mean calories are based on least-square means adjusted for age, education, body mass Index, physical activity, and cigarette smoking status; nonsignificant Interactions dropped, t Caffeine Intake Is expressed as mg/day x 1,000 cflvided by total daily caloric intake; caffeine means based upon least-square means adjusted for age and education; nonsignfflcant Interactions dropped. t Mean ± standard error. § p values based on regression models using the Ho scale as a continuous measure and adjusting for covartates In the above footnotes; nonsignificant interactions dropped.
p value§
3,292 ±41.8
Total
77.6$ 78.1 80.5 82.7
2,954 ± 3,292 ± 3,473 ± 3,548 ±
Calories/day
White men (n = 1,171)
Low Moderate High Very high
Hostfflty
TABLE 1. Total daily calories* and caffeine intakef by Cook-Medley hostility level, race, and sex: The CARDIA Study, 1985-1986
CD
tn o
Hostility and Coronary Risk and to smoke marijuana, they consume more calories than their low-hostility counterparts, and they drink more alcohol, a finding consistent with two other studies using the Cook-Medley Hostility Scale (16, 17). While 50 percent of those contacted were examined, we cannot be certain that these results generalize to the population contacted. The nonparticipants had a higher smoking rate than did the participants, and they also may have had a stronger association between hostility and health behaviors. Thus, we regard the findings as a possible conservative estimate of the relation of hostility to health behaviors. Nevertheless, the magnitude of the differences and the consistency of the findings suggest that hostility may underlie a clustering of risk factors. These different risk behaviors may work in concert to increase coronary heart disease risk and probably account for some of the previously reported relations between hostility and total mortality. However, not all the behaviors have been found to be detrimental. For example, few studies have looked at whether marijuana use is associated with coronary heart disease. Moderate alcohol consumption is associated with less coronary heart disease incidence; however, with increased alcohol consumption, there are more accidents, cancer, and cerebrovascular deaths (41). The consistency of the relations between hostility level and cigarette smoking, alcohol intake, and caloric intake across race, sex, age, and education increases the confidence in generalizing these findings to other young adults. However, not all the variables we measured are positively related to hostility. Even though those with more hostility consume many more calories, the percentage of calories from either saturated fat, unsaturated fat, or sucrose does not differ by hostility level. This is consistent with the results of Houston and Vavak (16), who found that choices of foods containing high sodium, cholesterol, or saturated fat did not differ between high- and low-hostility students. Contrary to the pattern found with alcohol and marijuana use, the hostility level was not related to number of cigarettes smoked
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per day, a finding consistent with that of Houston and Vavak (16) who also found the number of cigarettes smoked not to differ between high- and low-hostility college students. Except for white women, caffeine consumption was slightly less for the higher levels of hostility. Even though high-hostility subjects are likely to smoke more, to use more marijuana, to drink more alcohol, and to consume more calories than low-hostility individuals, they may have just begun to suffer the ill effects of these behaviors. Their waist/ hip ratio, which is related to increased stress hormones and mortality (42), is a little higher than that of their lower hostile counterparts. Nevertheless, serum cholesterol, reported physical exercise, exercise time on the treadmill, and blood pressure show no ill effects from cigarette, alcohol, and caloric consumption. However, the companion paper by Siegler et al. (17) presents prospective evidence that hostility measured at baseline is related to a higher body mass, a poorer lipid profile, and a greater likelihood of having a diagnosis of hypertension 20 years later. Perhaps it takes time for hostility to have an impact on physiologic risk factors. It is not clear from our cross-sectional findings whether increased alcohol, cigarette, and marijuana use and increased caloric intake make one more hostile; whether hostile individuals cope with their negative experiences by consuming more substances; or whether a third factor is related to both hostility and health behaviors. However, the prospective findings of Siegler et al. (17) relating baseline hostility level with higher body mass index, lipid ratio, and higher percentage of cigarette smokers 23 years later strengthen the interpretation that hostility is causally related to health behaviors. In a previous paper from the CARDIA Study sample, the hostile individuals reported more negative life events and less social support (19), a finding also reported by others (7, 43). With greater stress and less social support to buffer the effects of stress, the more hostile individuals may have coped with stress by consuming excess food, cigarettes, or marijuana.
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In summary, the results link hostility with tobacco and marijuana use, alcohol consumption, waist/hip ratio, and caloric intake and therefore provide a possible explanation for the association between hostility and mortality. If hostility contributes to these health behaviors, it may impede intervention efforts to change these behaviors.
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