Marital Discord and Coronary Artery Disease: A Comparison of Behaviorally Defined Discrete Groups.

The quality of marriage and similar close relationships is related to risk of coronary heart disease (CHD). Marital disruption (i.e., separation, divorce) and strain (i.e., conflict, dissatisfaction) predict the development of CHD (Matthews & Gump, 2002; De Vogli, Chandola, & Marmot, 2007) and poor prognosis for heart patients (Rohrbaugh, Shoham, & Coyne, 2006). Yet, the association of marital quality with asymptomatic atherosclerosis in otherwise healthy individuals is inconsistent. In the relevant studies to date, low marital quality has been related to more severe atherosclerosis in some sites (e.g., carotid arteries, aorta) but not in the coronary arteries (Gallo et al., 2003; Janicki et al., 2005). The uncertain role of marital quality in early stages of coronary artery disease (CAD) before the onset of clinically apparent CHD complicates the design of CHD risk assessments and risk-reducing interventions. Conceptual and measurement issues may contribute to this ambiguity. Prior studies have relied on self-reports of marital quality. Such measures are generally valid, but behavioral observation of marital interactions captures aspects of marital quality that self-reports sometimes do not (Snyder, Heyman, & Haynes, 2005). Also, studies of CHD conceptualize marital quality as a single dimension - labeled affiliation in interpersonal theories (Horowitz & Strack, 2011) - varying from friendliness and warmth to hostility and quarrelsomeness. A second major dimension in interpersonal theories – control - describes behavior as dominant and directive versus submissive and yielding, and is also important, as excessive or unfair control by a spouse contributes to low marital quality and increased conflict (Ehrensaft, Langhinrichsen-Rohling, Heyman, & O’Leary, 1999; Sanford, 2010; Smith, Traupman, Uchino, & Berg, 2010). Further, dominant interpersonal behavior is implicated in CHD development (Smith & Cundiff, 2011). Measurement of both the affiliation and control dimensions of marital functioning could also clarify sex differences in the health effects of marital factors. Women are sometimes more distressed by low affiliation in close relationships than are men, whereas men are often more troubled by concerns involving status or control (Smith et al., 1998). When marital quality is more closely associated with women’s health than men’s (Kiecolt-Glaser & Newton, 2001), this could be due to the relative emphasis on affiliation rather than control in most measures of relationship quality used in this research. To address these issues, Smith et al. (2011) examined associations of behavioral ratings of affiliation and control during marital disagreement with coronary artery calcification (CAC), a non-invasive measure of CAD, in outwardly healthy couples. Low affiliation was associated with more severe CAC in women but not men, whereas high control was associated with CAC in men but not women. Further, self-reports of marital quality were unrelated to CAC. Hence, behavioral measures of these two dimensions of marital functioning identified specific relationship risk factors for early stages of CAD. However, taxometric studies (Ruscio, Haslam, & Ruscio, 2006) have challenged such dimensional models marital quality. Marital discord may be more accurately represented as a discrete category, rather than the extreme of a continuous dimension, with an approximate prevalence of .20 among newlyweds (Beach, Fincham, Amir, & Leonard, 2005) and .30 among married persons more generally (Whisman, Beach, & Snyder, 2008). Hence, the association of behavioral measures of marital quality with early stages of CAD reported by Smith et al. (2011) might be limited to a somewhat artificial circumstance in which a dimensional structure is imposed on the categorical reality of marital discord. The association of early CAD with more naturally-occurring, discrete groups of discordant and non-discordant couples has not been tested to date. Here, we report further analyses of the Smith et al (2011) study to address this issue. Because the sample size of the study is too small for taxometric analyses (Ruscio et al., 2006), we used cluster analysis to identify discordant and non-discordant groups. After establishing that the behaviorally-defined groups represented discordant and non-discordant couples as intended, we tested the prediction that the discordant (i.e., low affiliation, high control) couples would evidence more severe asymptomatic CAD than the non-discordant (i.e., high affiliation, low control) couples.