Stressreduktion durch HRV-Biofeedback, achtsamkeitsbasierte Intervention und achtsamkeitsbasiertes HRV-Biofeedback unter Berücksichtigung individueller Stressmuster im Vergleich

Abstract

Contemporary western societies are constantly changing, and work environments are more complex than ever. Increased demands on employees can produce a sense of job strain and stress. Psychophysiological disorders due to work-related stress continue to be highly costly for individuals, societies and health systems. Approaches for cost-effective and easily accessible interventions for stress reduction are much needed in corporate health management. This dissertation contributes to the evaluation of stress management in the workplace context by comparing the two interventions heart rate variability-biofeedback (HRV-Bfb) and a mindfulness-based intervention (MBI) to a wait-list-control-group (WLC). Both interventions have been empirically shown to reduce stress. In addition, a new intervention, mindfulness-based biofeedback (MBB), which combines the singular methods to facilitate access to both interventions, was evaluated with pilot data. All three intervention types were compared using their standardized effect sizes. The individual effect of stress was assessed by the work-related coping behaviors using the German questionnaire ‘‘Arbeitsbezogenes Verhaltens- und Erlebensmuster’’ (AVEM: Pattern of Work-related Coping Behavior; Schaarschmidt & Fischer, 1996). Those patterns of work-related coping behavior were considered in the comparison of the three methods. In this three-armed randomized controlled trial (RCT), 69 healthy adults employed in the same organization (Staatstheater Stuttgart) were randomly distributed to one of the three groups HRV-Bfb, MBI or the WLC. 52 of these individuals met the inclusion criteria and were included in the analysis. Participants received training in either mindfulness or HRV biofeedback skills and practiced independently for 6 weeks on a daily basis. Outcomes were assessed at baseline (T0), six weeks after the initial training (T1) and at follow-up twelve weeks after the initial training (T2). Participants were assessed on psychological (stress perception, coping) and psychophysiological (HRV parameters and cortisol) parameters of stress. These were the primary outcome measures. Stress related symptoms (depressive symptoms, psychological wellbeing, mindfulness and self-compassion) served as secondary outcome measures. The WLC received the MBB intervention after the T2 follow-up. After another six weeks, post intervention measurements for MBB were assessed using the same outcome measures (T3). To explore the subjective experience of participants, qualitative semi-structured interviews were conducted at T1 and T2 with participants of the HRV-Bfb and MBI intervention groups. The interview was conducted with participants of MBB at T3. As expected, statistical analyses did not show any statistically significant differences in the effectiveness of HRV-Bfb and MBI groups. Findings suggest an overall reduction in stress for all groups, including the WLC. HRV-Bfb group improved only in measures of stress symptomatology. MBI group improved in measures of stress as well as in measures of attitude changes. Contrary to the hypothesis, neither of the intervention groups differed significantly from the WLC in stress reduction. Post-hoc moderator analyses suggest that in both intervention groups higher stress levels and/or lower mindfulness levels at baseline predicted greater reduction in stress indices post intervention. This finding could reflect a ceiling effect. The new intervention MBB could only partly be positively evaluated, with positive changes limited to stress coping and individual’s attitude. MBI might have a slightly stronger effect on stress reduction in comparison to HRV-Bfb and MBB, whereas MBB did not show greater stress reduction compared to the other interventions as expected. Effect sizes were mostly small to medium. Results of the qualitative interviews described a notable benefit of all three interventions with a stronger benefit from MBB, for which also the expected synergy effects of both singular interventions were reported. As there were not enough cases of patterns of work-related coping behavior, the role of this moderator on the outcome between group and stress reduction couldn’t be analyzed as planned. Instead, a subgroup analysis for the largely existing risk pattern B (reflecting burnout) was conducted and standardized effect sizes of the outcomes of the different groups (HRV-Bfb, MBI and MBB) were compared within this subgroup. These results, slightly stronger than the main analysis suggested greater stress reduction in MBI for this pattern of work-related coping behavior. In particular, structural factors of the organization itself such as a changed work load, might have been stronger than the intervention effect itself and may be responsible for the lack of significant differences between the intervention groups and the WLC. In this context, issues and challenges of field studies are discussed. The slightly stronger effect of MBI on stress reduction, which could be seen in the results might be related to the change in internal experience resulting from mindfulness training. The positive changes in measures of coping and attitude for MBB speak in favor of this assumption. These speculations have to be examined with larger scale RCTs, a different design or context. Besides the great relevance of the topic, the practical application of a field study and the use of both psychological as well as psychophysiological parameters to compare effectiveness of HRV-Bfb and MBI to a WLC is a novelty of the study. Moreover, it is one of the first studies evaluating MBB.