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Psychosomatic Medicine 67:343-352 (2005)
© 2005 American Psychosomatic Society

ORIGINAL ARTICLES

Social Network and Coronary Artery Calcification in Asymptomatic Individuals

Willem J. Kop, PhD, Daniel S. Berman, MD, Heidi Gransar, MS, Nathan D. Wong, PhD, Romalisa Miranda-Peats, NP, Maria D. White, NP, Magnolia Shin, NP, Melissa Bruce, NP, David S. Krantz, PhD and Alan Rozanski, MD

From the Department of Medical and Clinical Psychology, Uniformed Services University of the Health Sciences, Bethesda, MD (W.J.K., D.S.K.); and the Department of Imaging and Division of Nuclear Medicine, Cedars-Sinai Medical Center, Los Angeles, CA (D.S.B., H.G., N.D.W., R.M.-P., M.D.W., M.S., M.B., A.R.).

Address correspondence and reprint requests to Willem J. Kop, PhD, Department of Medical and Clinical Psychology, Uniformed Services University, 4301 Jones Bridge Road, Bethesda, MD 20814. E-mail: wjkop{at}usuhs.mil


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 
Background: Psychosocial factors are associated with the development of coronary artery disease. However, studies examining psychosocial factors as risk indicators for coronary artery calcification (CAC) have been inconclusive.

Methods: Seven hundred eighty-three participants (mean age 57.4 ± 9.3 years, 47% female) underwent CAC imaging using electron beam tomography. Psychosocial measures included social network (number of people in the household, marital status), socioeconomic status (education, income, and work status), history of depression, and current depressive symptoms as assessed with the Center for Epidemiologic Studies Depression (CES-D) scale. Assessments were also made for lipid profile, blood glucose, blood pressure, and health behaviors (smoking status, exercise, and diet).

Results: Calcification was present in 351 (44.8%) participants (CAC score range 0–3022; mean 111.5 ± 307.2). Indicators of social isolation (being single or widowed) were independently associated with elevated risk for the presence of CAC, even after adjustment for age, sex, systolic blood pressure, blood glucose, and low-density lipoprotein (adjusted odds ratios 1.80, 95% confidence interval [CI] = 1.05–3.10, and 2.48, 95% CI = 1.02–6.03, respectively). By contrast, health behaviors, socioeconomic status, and depressive symptoms were not related to CAC.

Conclusions: Social network indices such as being single or widowed are associated with CAC, independent of age and coronary risk factors. Because coronary calcification has been identified as a potential marker of early atherosclerosis, these findings may partially explain the predictive value of limited social networks for future adverse cardiovascular health outcomes.

Key Words: social network • social support • coronary calcification • risk factors • coronary artery disease • depression

Abbreviations: BMI = body mass index; CAC = coronary artery calcification; CAD = coronary artery disease; CES-D = Center for Epidemiologic Studies Depression; CI = confidence interval; DBP = diastolic blood pressure; HDL = high-density lipoprotein; LDL = low-density lipoprotein; OR = odds ratio; SBP = systolic blood pressure.


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
METHODS
 RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 
Various psychological factors are associated with the onset and progression of coronary artery disease (CAD) (1–3). The "social environment" has stood the test of time as a particularly potent CAD risk indicator. In addition to socioeconomic status (4–6), social environment is determined by social networks and social support. Epidemiologic studies have shown that low levels of social support among healthy individuals are associated with a 1.5- to 3-fold increased risk of future cardiac events (4,7–11) and all-cause mortality (12–16). Similarly, increased event rates have been noted during the follow up of patients with CAD with low levels of social support (17–19). These rates are at least comparable to the risks associated with hypertension, cigarette use, serum cholesterol levels exceeding 240 mg/dL, diabetes mellitus, and other established CAD risk factors (1). Despite these observations, there is debate as to what constitutes an adverse social environment. Regarding social support, both "structural" (i.e., the number of available social contacts, ranging from spousal and family support to community, club, and religious affiliations) and "functional" (e.g., instrumental and emotional support) components have been investigated. In addition, the quality and depth of positive emotional support appear to be important dimensions to measure (20,21). However, the instruments that have been used to measure these social factors have varied, and clarification of this issue is further complicated by the large number of research participants and the long follow-up time required to obtain sufficient statistical power when performing follow-up studies.

Recently, the measurement of coronary artery calcification (CAC) by electron beam computed tomography (CT) is increasingly used as a means of measuring the presence and magnitude of early atherosclerosis. Studies increasingly show that the magnitude of CAC is a potent predictor of cardiac outcomes, far exceeding the prognostic predictions derived from conventional CAD risk factors (22–26). Electron beam tomography CAC assessments have high sensitivity and moderate specificity for the detection of CAD (27). This implies that the measurement of CAC might be a useful surrogate marker for assessing the potential relevance of psychosocial risk factors in coronary disease. Prior studies crosstabulating psychosocial risk factors with CAC have largely focused on hostility and have revealed mixed results (28–31). In the present study, we elected to investigate the role of social environment in a large asymptomatic sample, assessing the relationship between multiple psychosocial variables (socioeconomic status, depressive symptoms, and social network) and CAC. We further explored the relative strength of these associations compared with known correlates of coronary calcification such as age and CAD risk factors.


   METHODS
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 
Participants
Local advertisements at Cedars Sinai Medical Center were used to enroll participants in the Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research (EISNER) study. Inclusion criteria were: 1) age ≤80 years; 2) intermediate or greater risk for developing CAD based on a prior validated algorithm (32,33); and 3) no symptoms or history of cardiovascular, cerebrovascular, or peripheral vascular disease. Exclusion criteria were: 1) prior cardiac electron beam tomography or other imaging within 90 days; 2) pregnancy; and 3) clinically unstable health status (e.g., life-threatening comorbidities). Participants were randomly assigned to two groups in a 2:1 ratio: Group 1 underwent screening for cardiovascular risk factors combined with CAC imaging (N = 783; 66.5%), and Group 2 was screened for risk factors without CAC imaging (N = 395; 33.5%). The reason for randomization was to evaluate potential referral biases in the prevalence of cardiovascular and psychosocial risk factors, and to allow future prospective investigation of the effects of CAC imaging on long-term health behaviors and cardiovascular end points (34). Table 1 describes demographics, cardiovascular risk factors, and psychosocial measures for participants with and without CAC imaging, and demonstrates that the randomization procedure was successful in establishing comparable groups. The present investigation includes the 783 participants who underwent CAC imaging (mean age 57.4 ± 9.3 years, 47% women). The study was approved by the Institutional Review Boards of the participating institutions, and all participants gave written informed consent before study enrollment.


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  		TABLE 1. Demographic Characteristics and Risk Factors for Coronary Artery Disease in Participants With and Without Coronary Artery Calcium Screening

 

Coronary Artery Calcification Assessment
Electron beam tomography was performed with an Imatron C 150 XL ultrafast CT scanner in high-resolution mode using a 100-ms exposure time. To visualize calcification in the coronary arteries, approximately 40 consecutive images were obtained in 3-mm segments from the root of the aorta to the apex of the heart. Images were obtained in diastole (80% of RR interval) while participants held their breath. The total radiation exposure was 0.6 rad per patient. The scans were scored in accordance with previously published methods (35) by a cardiologist blinded to cardiovascular and psychosocial risk factor status. Calcification was defined as present if at least 4 contiguous pixels were present with more than 130 Hounsfield units. Total CAC scores were calculated as the sum of the individual CAC scores for each of the 3 major coronary arteries.

Cardiovascular Risk Factors and Health Behaviors
Height, weight, body mass index (kg/m2), blood pressure, and heart rate were measured using standard procedures. Blood was assayed for glucose and lipoproteins (total cholesterol, low-density lipoprotein, and high-density lipoprotein) using a commercially available device (Cholestech Corp., Hayward, CA). Smoking status (never, history of, and current), exercise level (whether participants exercised >3 times/week for >30 minutes (36)), and amount of dietary fat intake (low, medium, high) were assessed using self-report measures.

Psychosocial Measures
Psychosocial risk factors with known predictive value for future cardiac events were evaluated using self-report measures (socioeconomic status, depressive symptoms, and social network).

Socioeconomic status was measured in 3 domains: education level, work status, and income (6). Level of education was categorized as low (incomplete or completed high school), middle (incomplete or completed college, vocational or technical school), or high (graduate education). Current employment status was categorized as full-time, homemaker, part-time, retired, and unemployed. Income categories were: low (<$20,000/yr), middle ($20,000–80,000/yr) and high (>$80,000/yr).

Depression was assessed using the 20-item Center for Epidemiologic Studies Depression (CES-D) scale (37). CES-D scores were analyzed as a continuous variable (potential range 0–60), and individuals at high risk of clinical depression were identified using an independently validated cutoff score (CES-D ≥16) (37). A total of 588 (75%) valid depression assessments were obtained from the 783 participants undergoing CAC imaging. Nonresponse to the CES-D was not related to CAC scores (p > .2). Participants also reported whether they had a history of depressive episodes.

Social network was assessed by marital status (married, divorced/separated, single, and widowed) and family structure. These social network measures have been shown to predict incident and recurrent cardiac events (7) and primarily assess the structural dimension of social support (i.e., the number of available individuals) based on functionally important support providers (i.e., family members) (7,14). Because traditional measures of marital status do not fully address household composition, we also examined the role of family structure, including the presence of children in the home, the reasons for living alone (separated, widowed, or single), and whether participants were married to their partner. Specifically, differences were examined among: 1) individuals who were married and living with children (total N = 161); 2) married, living without children (N = 272); 3) living with partner, never married (N = 35); 4) separated, living with children–single parent (N = 27); 5) separated, living with partner (N = 24); 6) separated, living alone (N = 76); 7) alone (single), never married (N = 50); 8) widowed with children or partner (N = 14); and 9) widowed, living alone (N = 19). Because both social network and coronary calcification are strongly influenced by age and sex, analyses for social network were specifically adjusted for potential biases related to age and sex.

Statistical Analysis
Data are presented as mean ± standard deviations or percentages. Coronary artery calcification scores were analyzed as continuous variable and as dichotomized measure (coronary calcification "present" CAC score ≥1 versus "absent" CAC scores 0) (27,33). Associations of cardiovascular and psychosocial measures with continuous CAC scores were analyzed using nonparametric Spearman correlation (Spearman’s rho) because CAC scores display a nonnormal and positively skewed distribution (see Fig. 1). To also enable parametric statistical analyses of variance, natural logarithmic transformations were applied to the CAC and CES-D data (indicated as CAC-l and CES-D-l), and ln-transformed continuous CAC-l data are presented and used in the analyses of variance. Dichotomized CAC scores (absent versus present) were examined using logistic regression analysis, using low-risk groups as reference, and associations between psychosocial measures and CAC status are presented as odds ratios (ORs) with 95% confidence intervals (CIs).



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  		Figure 1. Distribution of coronary artery calcification (CAC) scores in asymptomatic individuals with coronary artery disease risk factors. CAC scores display a characteristic positively skewed distribution. Logarithmic transformation results in a normal distribution of CAC data among participants with CAC (CAC scores ≥1).

 

Because traditional cardiovascular risk factors are interrelated, multivariate analyses were used to determine which factors revealed independent predictive value for CAC status. First, forward stepwise procedures were used to determine which demographic measures (age, sex, and race), cardiovascular risk factors (lipid levels, blood glucose, systolic and diastolic blood pressure, heart rate, and body mass index), and health behaviors (exercise, diet, and smoking status) were associated with CAC. Relationships of psychosocial measures with CAC were subsequently adjusted for those cardiovascular risk factors with predictive value for CAC status in the aforementioned multivariate model.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
DISCUSSION
 NOTES
 REFERENCES
 
The distribution of coronary calcification scores is displayed in Figure 1, both for all 783 participants and for the subgroup of 351 (44.8%) participants with coronary calcium present (i.e., CAC scores ≥1). Whereas the ln-transformed CAC scores in individuals with CAC scores ≥1 were normally distributed, the 3 other distributions manifested a significant positive skewness (p’s < .001). For all participants, the mean CAC value was 111.5 ± 307.2 (range 0–3022), and among participants with coronary calcification, the mean calcification score was 247.8 ± 351.0, with 47 (13%) manifesting CAC scores between 1 and 9, 146 (42%) with CAC scores of 10 to 99, 91 (26%) with CAC scores of 100 to 399, and 67 (19%) with CAC scores >400.

Demographic and Risk Factor Correlates of Coronary Artery Calcification
The nonparametric correlations between each of the continuous cardiovascular risk factors (e.g., age, lipid values) and CAC scores are presented in Table 2. The strongest correlation was observed between age and CAC scores (r = 0.39, p < .001), with modest correlations for systolic blood pressure (SBP), diastolic blood pressure (DBP), blood glucose, and high-density lipoprotein (HDL) values. Table 3 presents the associations between the categorical coronary risk factors and the severity and presence of CAC. Men had significantly higher CAC-l scores and higher frequency of coronary calcification (CAC score ≥1) than women. Black participants had less CAC than other participants. Consistent with the blood glucose findings, diabetes mellitus was associated with more severe and more frequent presence of CAC.


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  		TABLE 2. Bivariate Associations Between Cardiovascular Risk Factors (Continuous Variables) and Coronary Artery Calcification (Nonparametric r)

 

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  		TABLE 3. Associations Between Cardiovascular Risk Factors (Categorical Variables) and Coronary Artery Calcification

 

Because these cardiovascular risk factors are characteristically interrelated, we examined which factors were independently associated with CAC status. Multivariate forward inclusion of cardiovascular risk factors confirmed that age (OR = 1.11, p < .001) was the primary predictor of CAC status, followed by sex (OR = 3.46, p < .001), SBP (OR = 1.01, p = .014), blood glucose (OR = 1.02, p = .009), and low-density lipoprotein (LDL) (OR = 1.01, p = .014). The association between LDL and CAC became statistically significant in the multivariate model because age had a suppressor effect on the association between LDL and CAC status (i.e., both age and LDL were positively associated with CAC [Table 2], and age was inversely related to LDL [r = –0.15, p < .001]). Subsequent analyses examining psychosocial factors were adjusted for these risk factors (i.e., age, sex, SBP, blood glucose, and LDL).

Socioeconomic Status
Education level and income did not display associations with the severity or presence of CAC (Table 4). Retired workers had more calcification than other groups, but this relationship was entirely attributable to age as a common factor in both CAC and retirement status.


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  		TABLE 4. Association Between Socioeconomic Status and Coronary Artery Calcification

 

Depression
Continuous depression values were not related to CAC-l scores (r = –0.03, p > .5). The CAC-l score was similar among the 65 (11.1%) participants who had CES-D scores indicative of current depression (≥16) versus the 523 (88.9%) participants who had a CES-D score <16 (CAC-l scores of 1.46 ± 2.19 versus 1.97 ± 2.42, respectively). The frequency of calcification presence also did not differ between depressed and nondepressed individuals (41.5 versus 45.7%), and none of the individual CES-D items were significantly related to CAC status (Spearman rho <0.1). A history of depression was also not related to CAC status or CAC severity.

Social Network
The associations between family social environment with CAC-l scores and CAC status are shown in Table 5. Among the 9 social groups, the most severe age- and sex-adjusted CAC scores occurred among single individuals who were never married and among widowed individuals (p’s < .05). Consistently, the total number of individuals living in the household was inversely related to CAC-l scores (Spearman’s rho = –0.09, p = .027), and associations were similar for women (rho = –0.13, p = .020) and men (rho = –0.12, p = .024). Figure 2 illustrates the risk ratios for CAC as related to marital status and family structure. Compared with individuals who lived with their spouse and children (i.e., the reference group), significantly elevated risks of CAC were observed for single individuals who never married, widowed individuals (living with spouse or children or those living alone), and married individuals without children in the home (p’s < .05).


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  		TABLE 5. Association Between Family Social Environment and Coronary Calcification

 


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  		Figure 2. Risk of coronary artery calcification (CAC ≥1) among participants in social network groups based on family structure. Individuals living with "spouse and children" were used as the reference group. *p < .05, **p < .01; t = trend (0.05 < p < .10).

 

Because age and sex are important determinants of the family social structure and CAC, analyses were also conducted while statistically adjusting for these 2 demographic measures (adjustments for cardiovascular risk factors are described subsequently). Single individuals who never married (adjusted OR = 2.8, 95% CI = 1.3–5.8), those who were widowed and living with children or partner (adjusted OR = 3.2, 95% CI = 0.8–12.5), and widowed participants who lived alone (adjusted OR = 2.7, 95% CI = 0.8–8.9) remained at increased risk for CAC when adjusting for age and sex (p values showed a trend toward significance in the widowed participants as a consequence of the small sample size in these subgroups), whereas married individuals who had no children in the home were not at increased risk for CAC after adjustment for age and sex (adjusted OR = 1.2, 95% CI = 0.7–1.9). Thus, single and widowed individuals had elevated risk for CAC, independent of age and sex.

Examination of the data among the subgroup of participants with coronary calcification (i.e., CAC ≥1; N = 351) revealed no significant associations between family social structure, or any of the other psychosocial measures, with severity of CAC-l scores (p’s > .2).

Multivariate Analyses
To examine whether social network measures remained significantly associated with CAC status when adjusting for cardiovascular risk factors, multivariate analyses were conducted adjusting for the parameters that were independently related to CAC in the present study (i.e., age, sex, SBP, blood glucose, and LDL). As shown in Table 6, standard "marital status" categories were significantly related to the presence of CAC, with significantly increased risks among single (OR = 1.80; p = .034) and widowed (OR = 2.48; p = .046) participants.


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  		TABLE 6. Multivariate Analysis Examining Traditional Marital Status Categories and Cardiovascular Risk Factors for Coronary Artery Calcification

 

The detailed social network measure was also related to CAC such that living alone was significantly associated with CAC (OR = 3.07, p = .004), and widowhood revealed a trend toward an elevated adjusted risk (widowed living with spouse or children, OR = 2.78, p = .15; widowed living alone OR = 2.82, p = .094) in the multivariate model (Table 7).


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  		TABLE 7. Multivariate Analysis Examining Family Structure and Cardiovascular Risk Factors for Coronary Artery Calcification

 


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
NOTES
 REFERENCES
 
This study demonstrates that the frequency and severity of coronary artery calcification varies according to aspects of the social network. Individuals who were single and never married and widowed participants manifested increased CAC. These associations were not explained by effects of age or sex and remained present when adjusting for relevant cardiovascular risk factors.

In epidemiologic studies, the ability to divide social factors into the most relevant cardiovascular risk indicator subgroups has often been limited because of the overall low event rates. The use of CAC as a "surrogate endpoint" provides the unique potential to examine cardiovascular outcomes as related to smaller family structure subgroups with sufficient statistical power. These subgroups were chosen to better reflect the diversity of living arrangements in contemporary American society. Specifically, we examined social network from a family structure perspective in addition to the conventional marital status categorization (i.e., married versus single, divorce/separated, and widowed). These measures cover both the structural (number of available individuals) and, in part, the functional components of social support, because the household companions generally have the role of "significant others" (38). The observed associations were similar for men and women and remained significant after statistical adjustment for age, sex, and cardiovascular risk factors.

Comparison to Prior Studies
The current findings are consistent with the extensive literature demonstrating an inverse association between the size of an individual’s social network with risk of cardiovascular morbidity and all-cause mortality (4,7–11,13–16). Studies specifically focusing on the relationship of social isolation to recurrent cardiac events have been smaller in number, but also document a significant and reproducible relationship (17–19). Moreover, examining the size of social network as related to cardiac events suggest a gradient, which is confirmed in the present study; the greater the degree of social isolation, the greater the risk of adverse health outcomes (10,12,17). This is the first study to examine the potential relationship between social network and CAC.

Prior research assessing the relationship of psychosocial risk factors to CAC has yielded conflicting results. For instance, in a study of 630 consecutive army personnel, O’Malley et al. observed no relationship between CAC and measurements of hostility, depression, anxiety, and stress levels (28). By contrast, Iribarren et al. noted a significant association between measurement of hostility and CAC levels among 374 individuals in the CARDIA study (29), and one study suggested an association between CAC and the type A behavior pattern (30). Part of this discordance among these studies may relate to technical factors such as the nature of the psychometric measuring tools and/or the varying prevalence of CAC. For instance, the negative results of O’Malley et al. could have been influenced by the low (17.6%) prevalence of CAC in their study sample (28). Evidence based on other noninvasive markers of atherosclerosis such as carotid intimal thickening on ultrasound examination is in support of a relationship between psychosocial factors and the early markers of CAD (39–41).

Psychosocial factors related to CAD can be categorized into stable "chronic" factors such as limited social networks, low social support, chronic negative affect, and trait anger and hostility. By contrast, other measures focus on nonsustained "episodic" psychologic risk factors such as depression, exhaustion, or job loss (1,3). These latter factors do generally not reveal strong associations with underlying CAD severity (42,43). The lack of association between depressive symptoms and CAC in the present study is consistent with this hypothesis, because the CES-D measures current symptoms of depression and not chronic depressive conditions. On the other hand, socioeconomic status, which falls into the category of "chronic" psychologic factors, did not show significant associations with CAC in this study. These findings do not confirm observations by Gallo et al., who noted a marginally significant relationship between educational level and CAC presence (31). However, socioeconomic status may not have been optimally evaluated, because the present sample is highly skewed toward those who are affluent. In part, this is a ubiquitous current problem, because CAC screening is presently not widely covered by health insurance plans, thus resulting in a selective performance of CAC evaluations among individuals who participate in research and those who can afford such procedures.

Pathophysiological Considerations
Previous studies have linked social network size to a number of factors that might plausibly explain a relationship between social isolation and early atherosclerosis (20,41). First, social isolation has been linked to heightened neurohormonal levels in both experimental animal and human research. Studies indicate that social isolation is associated with higher levels of urinary epinephrine and serum cortisol as well as higher resting heart rates (for reviews, see (21,41,45)). Second, social isolation is characteristically associated with enhanced blood pressure and heart rate elevations to physical or emotional stimuli (46,47). Hence, social isolation could induce a sustained sympathetic hyperresponsiveness, which may precondition the coronary endothelium and promote vascular injury.

Social isolation may also promote atherosclerotic development indirectly by its association with adverse health behaviors such as smoking and maintaining poor, high-fat dietary habits (21). In the present study, markers of social isolation were associated with higher resting heart rate, body mass index (BMI), and current smoking status (adjusted for sex and age; data not shown). The observed lack of association between smoking status, BMI, and dietary habits with CAC is difficult to interpret and may in part reflect the homogeneous nature of the study sample. These findings may suggest that biobehavioral pathways other than health behaviors per se such as elevated reactivity and delayed recovery in response to exogenous challenges may account for the inverse relationship between social network size and CAC. We hypothesize that common mechanisms play a role in the adverse health consequences of social isolation (either related to being single or widowed). However, it is likely that additional population-specific biobehavioral pathways are involved in the subgroups of socially isolated individuals. For example, widowhood may be associated with CAC through reduced access to health care, bereavement, and other age-related challenges, whereas being single may be associated with personality traits relevant to coronary disease progression. Longitudinal investigations assessing both psychosocial factors and pathophysiological processes are needed to provide a better understanding of the association between psychosocial factors and CAD. Noninvasive technologies such as electron beam tomography may aid future research on how psychosocial factors influence atherosclerosis.

Study Limitations
The cross-sectional nature of this study precludes causal inferences based on the observed associations. Social network assessments were limited to family structure and marital status. We did not obtain systematic information regarding the duration of being single or widowed and cannot make definite conclusions regarding the chronic nature of these conditions. Neurohormonal correlates of the psychosocial measures in this study were not examined, which precludes conclusions regarding pathophysiological pathways. Furthermore, perceived emotional support from people in the social network was also not evaluated in this study, nor were assessments made of other community-based sources of support, which could be increasingly important in an aging population. Despite these limitations, we were able to observe a significant association between social isolation and the presence of CAC. We are currently investigating multiple psychologic parameters in a sample longitudinally assessed for CAC.

Finally, the typical lack of a normal distribution among CAC scores, also noted in this study, interferes with the application of standard parametric statistical analyses of variance. We therefore primarily focused the analyses on dichotomized end points (i.e., presence versus absence of CAC), which may have reduced the observed magnitude of effect sizes. CAC measures are sensitive but only moderately specific for the detection of underlying coronary artery disease as documented by coronary angiography (27). To address potential biases related to CAC specificity, we also examined higher cutoff points for CAC status, which revealed similar results with respect to marital status and CAC. Nonetheless, the present findings are not necessarily generalizable to atherosclerotic CAD progression in general.

Clinical Implications
The present findings support previous research on the effects of social network on cardiovascular health outcomes, and extend this literature by demonstrating increased coronary calcification among individuals with smaller social networks who are at high risk of being socially isolated (i.e., being single for a long period of time or widowed). These effects were independent of age, sex, and CAD risk factors, and may identify psychosocial risk indicators for early atherosclerosis. Because coronary calcium tomography is a relatively new technology, mostly uncovered by traditional health insurance, application of this methodology to study the potential impact of psychosocial factors on coronary disease has been limited. This study shows the feasibility of applying this technology to the study of psychosocial risk factors for CAD and suggests a number of important advantages of this approach compared with the traditional reliance on large follow-up studies. These include the ability to: 1) obtain results in relatively fewer research participants; 2) obtain results over a short period of time rather than relying on years of follow up; 3) have access to substantially more outcomes that could be conceived as "surrogate events," whether defined as the presence of coronary calcium or a specific level of coronary calcium; and importantly, 4) the ability to assess indices of early atherosclerosis in asymptomatic samples. However, the relatively modest specificity of coronary calcification for detection of underlying CAD requires careful consideration in the generalizability of the observed associations, because a substantial proportion of patients with coronary calcification scores ≥1 do not have documented coronary lesions >50%.

From an intervention perspective, beneficial effects may be anticipated by promoting social networks and social support (9–11,48). For example, in experimental studies, friendly social support in laboratory settings results in attenuated levels of blood pressure and heart rate elevations to arousing laboratory stimulation (46,47). Investigations of family structure and other social factors need to consider influences of sex, race, and ethnicity. More research is needed on the prognostic value of CAC screening in a wide range of populations. Potentially, the use of coronary calcium tomographic imaging could be used as a means of studying the interaction between psychosocial factors and biobehavioral processes in cardiovascular disease progression with more precision than previously possible.


   NOTES
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 NOTES
REFERENCES
 

The opinions and assertions expressed herein are those of the authors and are not to be construed as reflecting the views of the USUHS or the U.S. Department of Defense.

DOI:10.1097/01.psy.0000161201.45643.8d


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 

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