Svansdottir et al. BMC Public Health 2012, 12:42 http://www.biomedcentral.com/1471-2458/12/42 The DS14 comprises two seven-item subscales (NA and SI) in order to measure the tendency to experience negative emotions (NA, “I am often irritated”) and the tendency to inhibit self-expression in social interactions (SI, “I am a closed kind of person”), the two compo- nents of Type D personality. The report answer format is on a Likert scale ranging from 0 (false) to 4 (true). Total scores on both subscales range from 0 to 28. Par- ticipants were defined as having Type D personality if they scored ≥ 10 on both subscales [19]. A recent study using item-response theory has shown the cut of ≥ 10 to be the best to distinguish between Type D and non- Type D individuals [30]. Results from factor analyses on the scale have indicated a clear two factor structure, representing negative affectivity and social inhibition [19,31,32]. The Icelandic version of the DS14 has good internal consistency (Cronbach’s a = 0.87-0.88 for NA; Chronbach’s a = 0.84-0.85 for SI) and psychometric evaluations have supported the construct validity of the scale [33]. The HADS measures symptoms of anxiety and depression and was specifically developed and tested in physically ill people [28]. This questionnaire contains seven items for each mood status. Participants answer on a four-point scale (0-3) how well each statement refers to them, and total scores for each domain range from 0 to 21. The Icelandic version of the HADS identi- fies symptoms of depression and anxiety sufficiently well [34], and reliability estimates across various studies range from 0.78-0.86 for anxiety and 0.65-0.85 for depression [35]. Continuous scores on the HADS were used for the main analysis and dichotomous scores were used for a logistic regression. Depression and anxiety scores on HADS were categorized in a similar way as recommended by the authors, with the exception that borderline symptoms and full symptoms were pooled into one category, such that scores ≥ 8 indicated pre- sence of symptoms of anxiety and depression. The PSS is a 14-item questionnaire which measures perceived stress [29], more specifically, the degree to which situations in one’s life are appraised as stressful. Items include questions such as “In the last month, how often have you felt nervous and stressed” and “In the last month, how often have you felt that you were unable to control the important things in your life?” Responses are measured on a five-point Likert scale ran- ging from 0 (never) to 4 (very often), and the total score ranges from 0 to 56. The PSS has good psychometric properties [29,36]. The Icelandic version of the PSS has comparable psychometric properties to the original ver- sion (Davíðsdóttir S, Bachman T, [Association of stress and gender with health and health-habits], Bachelor’s thesis, University of Iceland, 1991), with reliability coef- ficients of a = 0.89 in a healthy sample and a = 0.90 in Page 3 of 10 a patient sample (Svansdóttir E, [Translation and psy- chometric evaluation of the DS-14 scale among univer- sity students and heart patients], cand. psych thesis, University of Iceland, 2006). In the current study, con- tinuous scores were used for the main analysis. To indi- cate heightened symptoms of perceived stress, we used a cut-off score at the 75th percentile. Health-related behaviors measured at four-month follow- up Assessment of health-related behaviors was conducted four-months after discharge, by a phone call by a researcher to participants, where standard questions regarding exercise, diet, smoking and psychopharmaco- logical medication use were administered. Specific ques- tions included: a) whether patients engaged in sufficient exercise per week (> 20 min 3× a week); b) whether patients had gained weight after discharge (yes, no); c) rehabilitation attendance after discharge (yes, no); d) whether they had breakfast every morning (yes, no); e) daily consumption of fruits and vegetables (not daily, daily); f) frequency of fish consumption (< once per week, weekly); g) smoking (yes, no); and h) regular use of sleeping pills, antidepressants, and/or anxiety-redu- cing medication. Statistical analyses Prior to analysis, missing values on the DS14, HADS and PSS were replaced if the number of missing items per participant did not exceed three on the DS14 and HADS subscales, or four for the total PSS scale. Missing items were replaced with each participant’s average score on the subscale the missing items belonged to. For each scale, replaced missing items were ≤ 1% of the total number of items. Four patients (1.5%) did not complete the HADS scale adequately and were excluded from all analysis that included HADS scores. Sixteen patients (6%) had ≥ four items missing on the PSS scale, and were excluded from analysis involving PSS scores. Differences in demographics, clinical variables and health-related behavior between Type D and non-Type D individuals were explored with chi-square calculations for nominal variables and independent t-tests for contin- uous variables. Independent t-tests were administered to examine basic differences in anxiety, depression and stress scores between Type D and non-Type D patients. The association of Type D personality with anxiety, depression and perceived stress was assessed with multi- ple linear regressions. Each separate model was imple- mented with a hierarchical entry, where Type D personality was inserted at the first step, while age, gen- der, disease severity, cardiac history, education and family status were added in the second step as covari- ates. Two outliers were identified in the anxiety and