THE FACTOR ANALYTIC STRUCTURE OF SEVEN PHYSICAL CHD RISK FACTORS: A REPLICATION STUDY

LOGAN WRIGHT, STEVE MURCER, KATHLEEN ADAMS AND SHELL1 WELCH

University of Oklahoma

DONNA PARIS

Baptist Medical Center Oklahoma City, Oklahoma

An attempt was made to replicate the results of an earlier confirmatory factor analysis of the seven traditionally employed physical risk factors for CHD. As with the first investigation, a two-factor solution was confirmed; only family history loaded on factor 1; the remaining six risk variables (smok- ing, serum cholesterol, blood pressure, diet, exercise, and weight control) comprised factor 2. These findings may reflect a broad personality trait, i.e., generalized lack of self-control, which could underlie much CHD risk not associated with a family history of heart disease. Implications are drawn for research and practice in the areas of cardiac rehab and prevention.

To date, only one study (Wright, Carbonari, & Voyles, 1992) has examined the factor analytic structure of the traditionally employed (Rosenman et al., 1973) physical risk factors for coronary heart disease (CHD). Using predictions based on clinical obser- vations, the original Wright et al. study subjected the scores for seven physical risk fac- tors of 40 hospitalized CHD patients to a LISREL-type confirmatory factor analysis. These single risk factors include family history, smoking, serum cholesterol, blood pressure, physical exercise, diet, and weight control.

The Wright et al. study successfully confirmed a two-factor solution, one of which had a loading for only a family history of CHD, while the other six risk variables com- prised the second factor. It was concluded that a pervasive behavior factor, possibly involving a generalized lack of self-control, may underlie much of the noninherited risk for CHD.

The earlier two-factor finding, if reliable (replicable) across samples, could have both clinical and research implications. One is that some cardiac rehab programs (or possibly prevention efforts) may be more effective if focused more on the pervasive per- sonality trait of overall self-control, rather than on specific behaviors and/or their physical consequences, e.g., on smoking or exercise or diet, etc. Such an approach might best be substituted for more didactic or verbally psychotherapeutic efforts aimed at smok- ing, weight control, blood pressure, etc. because unlike individual operant and biofeed- back programs, these so-called teaching or talking treatments are not bolstered by em- pirical evidence to support either their initial efficacy or lasting effects. The purpose of the present investigation was to determine whether the results of the earlier study by Wright et al. were reliable and, thus, could be replicated.

METHOD

Subjects The procedures in this study were identical to those of the earlier study by Wright

et al. (1992). Subjects were a new group of 40 married Caucasian males between 40 and

Correspondence should be addressed to Logan Wright, Department of Psychology, University of Oklahoma, Norman, OK 73019-0535.

216

CHD Risk and Cardiac Rehabilitation 217

55 years of age (M = 50.44 years) who were patients on a coronary care unit at a large southwestern medical center. All subjects had experienced at least one myocardial in- farction (MI). Twenty-nine subjects had experienced one, 6 had experienced two, and 5 had experienced three or more MIS. Twenty-two of the subjects had undergone coronary bypass surgery, and 12 had received angioplasty. There were no refusals to participate in the study.

Information on the seven risk factors of family history, smoking, blood pressure, serum cholesterol, diet, exercise, and weight control was obtained both from patients’ charts and from a single interview. The information was gathered by a cardiac rehab nurse, who was naive as to the purpose of this study. Each risk factor was scored accord- ing to a method originally suggested by Rosenman et al. (1975).

The smoking score was the average number of cigarettes per day times number of years smoked. The weight control score was a ratio determined by dividing height in inches by weight in pounds (a method advocated later by Stunkard and Baum, 1989). The other five risk factors were scored as follows:

Self reported Family History 1 = No family history. 2 = Secondary family history (aunts, uncles, and grandparents only). 3 = Family history in only one immediate family member (father, mother, brother,

3.5 = Family history in one or more immediate family member and in one or more

4 = Family history, multiple: i.e., two or more immediate family members.

sister).

secondary family member.

Serum Cholesterol Average of all available combined HDL/LDL readings (only first reading of a given

year was used in the event there were multiple readings available for a given year). The average of multiple readings in one year was employed. Also, no post infarc readings from present hospitalization were employed.

Blood Pressure

(combined systolic and diastolic). Systolic and diastolic readings combined - all available readings for blood pressure

1 = below 190 and no medication. 2 = 190-210 and no medication. 3 = 210-230 and no medication. 4 = 230 and above or on medication. 5 = 230 and above and on medication.

Self-reported Exercise Style 1 = Little or no exercise at work or home. 2 = Moderate exercise at work. No formal exercise program. 3 = Routine vigorous exercise at work, or formal exercise program (less vigorous

4 = Vigorous exercise at work and formal exercise program (less vigorous than

5 = Formal exercise program (20 minutes or more of vigorous exercise, excluding

than level 5) .

level 5).

walking) done 3 or more days a week. Self reported Diet

Typical diet practiced prior to documentation of CHD. 1 = Deliberately restricted high fat foods and chose high fiber foods.

218 Journal of Clinical Psychology, March 1994, Vol. 50, No. 2

2 = High fat and high fiber. 3 = High fat and low fiber. Obtained data were subjected to a Lisrel-type confirmatory factor analysis using

polycloric correlations (Joreskog & Sorbom, 198 1) for confirming the two-factor outcome suggested above, that is, with family history the only variable associated significantly on the first factor, and with all other variables associated with the second factor.

RESULTS

Obtained data were subjected to a Lisrel-type confirmatory factor analysis using polycloric correlations (Joreskog & Sorbom, 1981) for confirming the two-factor Wright et al. (1992) study. The correlation between factors 1 and 2 was - .13, com- pared to - .42 in the first investigation, which, while not exact, is similar to the correla- tion obtained in the earlier study.

The factor loadings from this study are shown in Table 1, with the corresponding results from the first study (Wright et al., 1992) shown in parentheses.

Table 1 Correlations of Seven CHD Risk Variables with Each of Two Factor Analytically Derived Factors"

Factor 1 Factor 2

Smoking .oo (.oo) .14 (.17)

Cholesterol .oo (.W) -.29* (.03) Blood Pressure .oo (.W) .35* (.31)*

Family History l.oo** (l.oo)** -.07** (.M)

Exercise .oo (.oo) 1.00** (.86)** Diet .oo (.oo) .30* ( .5 l )**

Weight Control .oo (.oo) -.14 ( .58)**

"Corresponding results of the earlier Wright et al. study are shown in parentheses. *p < .025. **p < .001.

As can be seen from Table 1, there were two factor loadings in this study that differ significantly from those of the investigation that was being replicated. Weight control failed to load significantly on factor 2, whereas it had correlated significantly with that factor in the first study. And, the variable of serum cholesterol did correlate signifi- cantly and negatively with factor 2 in this investigation, whereas it did not load signifi- cantly on that factor in the first study.

The fact that some factor 2 loadings are modest and that cholesterol correlates significantly, but negatively, with factor 2 suggested initially that a three-factor solu- tion might better explain the variance in the data obtained here. However, as with the original Wright et al. (1992) study, a three-factor solution (with the third factor having a strong loading for cholesterol) produced a poorer goodness-of-fit.

Table 2 shows the intercorrelation matrix obtained in this investigation, with the corresponding results from study one provided in parentheses.

While the internal consistency of factor 2 is limited, the two-factor solution that involved: (1) family history and (2) the remaining six CHD risk variables did provide the best solution.

CHD Risk and Cardiac Rehabilitation 219

Table 2 Intercorrelations f o r Seven Study Variables”

Family history Smoking Cholesterol Blood pressure Exercise Diet

Smoking -.01 (.08) Cholesterol .23 (.07) -.14 (.07) Blood pressure .I6 ( - .01) .30 (.37) . I 8 (.35) Exercise .I0 (-.34) -.24 (.09) .06 (.03) - .15 ( . IS ) Diet -.08 (-.20) .07 (.14) .21 (-.22) .21 (.06) .23 (.37) Weightlheight - .04 (-.24) - . 1 1 (.18) .26 (.29) .32 (.31) - .09 (.46) .I0 (.19)

“Corresponding results of the earlier Wright et al. study are shown in parentheses.

DISCUSSION

The fact that a two-factor solution for CHD risk variables has been both confirmed and replicated lends additional substance to the belief that a single variable may underlie a significant portion of CHD risk that is not associated with a family history for CHD. Because the six variables in factor 2 are known to be affected by life style, a pervasive and more self-imposed (rather than genetic) personality trait of limited self-control ap- pears to be responsible to some extent. Our results support concerns about the utility of didactic (including cognitive restructuring) or dynamic (but not operant, biofeed- back, etc.) cardiac rehab programs that are targeted on the highly specific physical effects of cigarette smoking, poor diet, inadequate exercise, etc. Our findings encourage efforts to explore new methods, possibly for both cardiac aftercare and prevention, that at- tempt to modify a broader dimension of personality that involves individuals’ broad, general, self-control capability.

One eventuality not considered here (because this was an exact replication of an earlier study) is the fact that family history might be contaminated by family size, since an individual with many relatives is more likely to have one with a history of CHD than is an individual with few relations. Family history also may be contaminated by age of subjects because the relatives of older subjects are likely to be older and to have gone further into the risk period for CHD. A family history measure that is independent of age and family size would be useful in future research of this type.

Granted that 40 subjects represent a relatively small sample, it is consistent with the fact that this is a replication of an earlier investigation. Obviously, the use of hospitalized, middle-aged, White males indicates that the sample is highly select. As such, the generalizability of these data clearly is restricted. However, such selectivity is also necessary for replication purposes and provides at least a simple subgroup to which results appear to be generalized appropriately. It remains for future investiga- tions to determine the degree to which these findings apply to groups of differing age, gender, ethnicity, disease involvement, etc.

REFERENCES

JORESKOG, K. G. , & SORBOM, D. (1981).

ROSENMAN, R. H., BRAND, R. J . , JENKINS, D. , FRIEDMAN, M., STRAUSS, R., & WURM, M. (1975).

Lisrel V: Analysis of linear structural relationships by maximum likelihood and least squares methods. Uppsala, Sweden: University of Uppsala.

Coronary heart disease in the Western Collaborative Group Study: Final follow-up experience of 8 !A years. Jour- nal of the American Medical Association, 233, 872-877.

STUNKARD, A. J., & BAUM, A. (1989). Perspectives in behavioral medicine. Eating, sleeping andsex. Hillsdale, NJ: Erlbaum.

WRIGHT, L., CARBONARI, J . , & VOYLES, W. (1992). A factor analytic study of physical risk variables for CHD. Journal of Clinical Psychology, 48, 165-170.