Is social isolation/alienation confounded with, and non-independent of, emotional distress in its association with early onset of coronary artery disease?

Both emotional distress (ED) and social isolation/alienation (SI/A) have been found to prospectively predict adverse cardiac events, but few studies have tested the confounding/redundancy of these measures as correlates/predictors of outcomes. In this study, 163 patients with documented coronary artery disease (CAD) were interviewed for multiple indices of SI/A and administered the Symptom Checklist 90 - Revised (SCL90R). A spouse or friend provided an independent rating of ED using the spouse/friend version of the Ketterer Stress Symptom Frequency Checklist (KSSFC). The measures of ED and SI/A covaried. All three scales from the KSSFC (depression, anxiety, and "AIAI" - aggravation, irritation, anger, and impatience), and three scales from the SCL90R (anxiety, depression, and psychoticism), were associated with early Age at Initial Diagnosis (AAID) of CAD. Neither three scales derived from the SCL90R (shyness, feeling abused, and feeling lonely) nor the interview indices of SI/A (married, living alone, having a confidant, self description as a lone wolf, and self-description as lonely) were associated with early AAID. Thus, it is concluded that the present results indicate that ED and SI/A are confounded and that, even when tested head-to-head in a multivariate analysis, only ED is associated with AAID.