Background

Few studies have investigated the trajectory of depression and level of physical activity, in patients with heart disease during a psychosocial intervention such as internet based cognitive behavioural therapy (iCBT). For health care professionals in cardiac care it is important to know when an improvement in depression can be expected during iCBT and if this improvement can be associated with physical activity. The aim of this study therefore is, 1) to investigate the trajectory of depression and physical activity during participation in an iCBT program compared to a moderated online discussion forum (ODF). 2) to investigate the association between improvements in depression and physical activity.

Method

A sub-analysis of data collected in a randomised controlled trial (RCT) that evaluated the effect on depression of a nine-week iCBT program guided by nurse. In the RCT, 144 cardiac patients with at least mild depression were randomised to iCBT or ODF. The iCBT program consisted of seven modules where feedback was provided by nurses. The ODF consisted of nine discussion topics moderated by a nurse.

Data for the present analysis was collected at baseline, once weekly during the intervention period, and the follow-up. Depression was measured by Montgomery Åsberg Depression Rating Scale – self rating (MADRS-S). Two modified items from the Physical Activity Questionnaire measured frequency and length of physical activity. Frequency was scored between “none of the days” (0) to “often, 5-7 days” (3). Length was scored from 0 (0 minutes) to 4 (more than 60 minutes). A combined physical activity factor was calculated by multiplying frequency and length scores.

Results

Figure 1a illustrates the trajectory of depression from baseline assessment until the follow up. There was a significant time and group interaction (F=9.98, p<.001, η²=.106) favouring iCBT. The significant difference in depression between iCBT and ODF started at week six and remained to the follow-up. Figures 1b to 1d illustrates the trajectories of physical activity. We found a significant interaction of time and group favouring iCBT for the combined physical factor (F=2.36, p=0.019, η²=.028). The interaction effects for time and group for frequency (F=1.95, p=0.056) and length in physical activity (F=1.26, p=0.272) was not statistically significant. Pearson correlational analyses showed a positive association between improvement in depression and increase of physical activity (r=.256, p=.004). For the iCBT-group this association was stronger (r= .312, p=.011), whereas there was no significant correlation in the ODF group (r= -.006, p= .965)

Conclusion

Both depression and physical activity improved during the course of the nine week iCBT program. However, improvement occur more clearly after half the duration of iCBT program. Early in the program, a temporary worsening of depression was seen. This indicates that patients need support and encouragement to complete the iCBT program, which gives them greater opportunities to improve in depression and physical activity.