Depression, coronary artery disease and change of lifestyle

Depression has been identified as a risk factor for the development of coronary artery disease (CAD) and has been associated with functional impairment and disability, poor outcome of lifestyle changes, incomplete and prolonged recovery, repeated coronary events, and mortality. Thus, there is substantial evidence that depression has a negative impact on CAD.

The thesis consists of two interdependent approaches. The aim of the first approach (Studies I-II) was to evaluate two instruments assessing depression, both suitable for patients with a physical disease like CAD. The overall aim of the second approach (Studies III-V) was to study immediate and long-term effects on and of depression in relation to a comprehensive behaviour-oriented rehabilitation program on lifestyle changes in CAD patients.

In Study I, the Beck Depression Inventory (BDI) was analysed with respect to whether a supposed physical component of BDI could be interpreted as symptomatic of the physical disease and not of depression. Results showed that this component could be confounding when assessing depression in patients with a physical disease, such as CAD.

In Study II, the Hospital Anxiety and Depression Scale (HAD), covering only nonphysical items, was validated on a Swedish population from the county of Jämtland, and also compared with the BDI. The HAD appeared to have a strong factor structure and was relatively strongly correlated with the BDI.

Studies Ill and IV investigated the effects of a comprehensive rehabilitation program on depression, the effects of different pre-treatment levels of depression, and in Study IV also the effects of depression changes during the treatment period, on lifestyle habits (diet, smoking, exercise and relaxation) and the use of hospital care. Patients (comprising subjects with AMI, CABG, PTCA or angina pectoris not invasively treated) were divided into three subgroups based on their level of depression (non-depressed, mildly depressed and clinically or highly depressed).

In Study Ill, patients with a mild level of pre-treatment depression experienced short- term reductions of depression that were maintained at the 12-month follow-up. Clinically depressed subjects experienced less positive results, with no significant immediate reductions (except for the physical symptoms) and a relapse regards the nonphysical symptoms to baseline level after 12 months. In Study IV, all groups, regardless of pre-treatment levels of depression, significantly decreased the level of depression in the short run, but the improvements were not entirely maintained at the 12-month follow-up. However, in comparison with baseline levels, improvements were maintained for the initially depressed patients. As regards change of lifestyle, neither pre-treatment level (Studies Ill and IV), nor change of depression during the 12-month follow-up period (Study IV), had any influence on lifestyle changes or the amount of hospital care.

Study V, demonstrated the impact of depression on work resumption rates in CAD patients participating in the comprehensive rehabilitation program. Depressed (clinically and mildly) patients were less successful than non-depressed in work resumption at full time hours, but mildly depressed patients returned at reduced working hours to the same extent as non-depressed subjects.

In conclusion, it is likely that the rehabilitation program had some effect on depression, especially on mild depression. Above all, the program influenced depressed patients to change their lifestyle to the same degree as non-depressed patients, which, in the long run, might lead to diminished negative effects of depression on the progression of CAD.

List of scientific papers

I. Soderman E, Lisspers J (1997). "Diagnosing depression in patients with physical diseases using the Beck Depression Inventory (BDI)." Scandinavian Journal of Behaviour Therapy 26: 102-112

II. Lisspers J, Nygren A, Soderman E (1997). "Hospital Anxiety and Depression Scale (HAD): some psychometric data for a Swedish sample. " Acta Psychiatr Scand 96(4): 281-6
https://pubmed.ncbi.nlm.nih.gov/9350957

III. Lisspers J, Soderman E, Sundin O, Nygren A (1999). "The effects on and of depression- An exploratory study of rehabilitation and secondary prevention in coronary artery disease." Scandinavian Journal of Behaviour Therapy 28: 9-18

IV. Soderman E, Lisspers J, Sundin O (2001). "Impact of depression on lifestyle changes in patients with coronary artery disease." (Submitted)

V. Soderman E, Lisspers J, Sundin O (2001). "Depression as a predictor of return to work in patients with coronary artery disease." Social Science & Medicine (In Print)