Svansdottir et al. BMC Public Health 2012, 12:42 http://www.biomedcentral.com/1471-2458/12/42 these and SI main effects, the interaction term of by SI was not significant in these analyses of anxi- ety, depression and stress. In binary logistic regression models of health-related behaviors, the by SI inter- action term was associated with higher odds of smoking at follow-up (OR 1.50, 95% CI: 1.01-2.21, p = 0.04) and less fish consumption (OR 0.48, 95% CI: 0.31-0.74, p = 0.001), and with more use of antidepressant medica- tions (OR 1.89, 95% CI: 1.29-2.77, p = 0.001). No asso- ciation was found between NA, SI, or by SI with weight gain (in patients with BMI ≥ 25) or use of sleep medication. Discussion This study investigated the association between Type D personality and psychological distress in Icelandic car- diac patients, explored whether the association was con- founded by indicators of disease severity, and examined the relationship between Type D personality and certain health-related behaviors. As expected, patients with Type D personality had a worse psychological status compared to their non-Type D counterparts, which was independent of the patient’s demographic status and markers of disease severity. These results are in support for the notion that Type D personality is associated with impaired psychological well-being in cardiac patients, and are congruent with previous findings [8,9], where Type D has been associated with a three-fold risk of increased psychological distress [17]. Further analysis revealed that the association between Type D and poor psychological status was mainly driven by NA, but that SI also had a significant unique contribution to depres- sion and perceived stress. and SI shared consider- able variance in depression/stress scores, indicating the effect of Type D personality. Other researchers also found that the interaction of and SI predicted increased stress levels [24]. Regarding health-related behaviors, Type D patients displayed a lower prevalence of fish consumption and a trend towards less fruit and vegetable consumption compared to non-Type Ds, as well as a predisposition to smoke at follow-up and a higher prevalence of sleep- and antidepressant medication use. The higher preva- lence of psychopharmacological medication use has been noticed previously, where post-MI patients with a Type D personality were significantly more likely to use benzodiazepines as compared to non-Type D patients [38], and provides further support to the current find- ings that Type D individuals experience more symptoms of anxiety, depression and stress. The finding that Type D personality was not asso- ciated with indicators of disease severity is in line with previous findings [14,18,39], providing further evidence that Type D personality is not related to disease severity. Page 7 of 10 Other studies also found no association between psy- chological factors and extent of coronary atherosclerosis [40]. Hence, the adverse effects of Type D personality on cardiac prognosis may be mediated through other pathways, such as behavioral and physiological factors [13,23,24]. Apart from the unexpected link between Type D and a lower prevalence of hypertension treatment, no asso- ciation was found with the traditional CAD risk factors. This fits well with the general consensus that the influ- ence of Type D on cardiac health is not mediated through biomedical risk factors [14,16]. The lower hypertension treatment prevalence could be due to a poorer self-management in Type D patients, as Type D has previously been associated with poor medication adherence [41]. Type D individuals are also less likely to seek appropriate medical care [42] or to have regular medical check-ups [22]. Re-analyses of significant associations of Type D per- sonality with outcome variables, using continuous NA, SI, and by SI scores confirmed the association of the and SI subscales with depression, and the main effects of with anxiety and stress. The by SI interaction term was not significant in these analyses, probably as the main effects of the Type D subcompo- nents were already accounted for. Regarding health- behaviors, the by SI interaction term was associated with more smoking and lower fish consumption and with use of antidepressant medications. These find- ings suggest that categorical and dimensional definitions of Type D personality are not necessarily mutually exclusive, but represent two different ways of capturing the psychological profiles of individuals [43]. Behavioral processes are believed to constitute one of the main mediating mechanisms linking personality and psychological distress with impaired health [44] and increased CVD risk [23,26], and recent findings suggest that health-related behavior may explain 40% of the association between personality traits and mortality [45]. Thus, management of behavioral processes such as health-related behavior may be crucial to reduce dis- tress-related CVD risk [23]. The current findings sug- gested that some important aspects of health-related behavior may differ between Type D and non-Type D patients. A distinct difference in fish consumption was found, and previously, Type D personality has been associated with less sensible diet in healthy individuals [22]. Healthy diet choices are considered an important part of CVD risk reduction [46], where for example increased consumption of fruits and vegetables [47,48], fish, and reduced intake of fried foods [46,47] are recommended. Unhealthy diet has been associated with an increased risk of acute myocardial infarction world- wide, and is estimated to account for nearly 30% of the