Synergistic effects of multi-level suicide preventive interventions: Important,but difficult to disentangle

Aim of the authors of the article ‘Best strategies for reducing suicide rate in Australia’ is to estimate the possible contribution of nine different evidence-based measures to prevent attempted and completed suicides. The findings on effects sizes and impact of the different measures are supposed to provide orientation for the design of national multi-level programmes for preventing suicidal behaviour in Australia.

Causal factors for suicidal behaviour are complex, interrelated and different for each suicidal act. Having additionally in mind the low base rate of attempted and completed suicides, the aim of the paper is very ambitious and the authors correctly conclude that there is an absence of data available to be able to calculate the potential reductive effects of a number of suicide prevention interventions on suicide deaths and attempts. The authors have carefully addressed several limitations and caveats of their approach, and we would like to add three further aspects which we believe are relevant when trying to estimate suicide preventive effects of certain interventions:

• 1. It is not transparent how the authors have selected the nine different evidence-based measures included in the analysis. A central element of suicide preventive strategies, namely, the care for people with psychiatric and especially depressive disorders, is lacking, for example. The majority of completed and attempted suicides occurs in the context of such disorders as shown in psychological autopsy studies and supported by daily clinical experience. Depression is the most important disorder in this context because of its prevalence and the fact that effective treatments are available, but used only in a minority of patients affected. Reducing treatment gaps for depression and other psychiatric disorders is therefore a central element in every strategy intending to prevent suicidal behaviour. This is supported by the fact that improving the care for people with depression has already been a central element in several community-based interventions showing preventive effects on suicidal behaviour (Hegerl et al., 2013; Hübner-Liebermann et al., 2010; Székely et al., 2013). This is in line with the finding that the best predictor of change in suicide rates in 29 European countries was not unemployment rate, gross domestic product (GDP) or alcohol consumption, but change in antidepressant prescription rates (Gusmão et al., 2013).

One out of the nine included prevention strategies is a public relation campaign. Experience from the European Alliance Against Depression (www.eaad.net) indicates that even intense public relation campaigns targeting stigma and knowledge deficits concerning depression and involving measures such as posters, public events, leaflets and cinema spots induce only relatively small changes in attitudes, knowledge and stigma in the general population (Coppens et al., 2013). However, this does not allow the conclusion that such campaigns are of small value. Such campaigns are carefully noted by psychiatric patients and their relatives, who see, e.g., the posters in public places. Experiences from many different intervention regions in Europe show that this can motivate people with psychiatric disorders to seek help and in addition generate the impression in depressed people that there is more support, acceptance and understanding in the general public. The perceived stigma is decreasing, even if real stigma in the general population has not changed much. Reducing perceived stigma can induce various effects on help-seeking behaviour, e.g., people suffering from depression might speak with a friend or neighbour and therefore step out of their isolation, and this can reduce the risk of suicidal behaviour (Coppens et al., 2013).

• 2. Implementing different intervention measures simultaneously at different intervention levels generates not only additive but also synergistic effects via complex, interacting causal chains. Systematic process analysis and experience from many intervention regions in Europe show, e.g., that the opening ceremony of a regional alliance against depression and the public relation campaign motivates people with depression to seek help with their general practitioner (GP), which then motivates the GPs to increase their expertise in dealing with depression and other psychiatric disorders and to participate in the GP-trainings offered within the alliances against depression. Furthermore, the posters at public places and in the practices of the GPs might facilitate that the GP confronts a patient, coming, e.g., with chronic lower back pain and a somatic disease concept with a potential psychiatric diagnosis.

• 3. It is rather unrealistic to attempt to disentangle all of these mutually reinforcing mechanisms. Furthermore, the four-level intervention programme has been found to have the potential to unfold catalytic effects, meaning unintended new care facilities for people with mental disorders or possible effects by improving cooperation within the different levels of care.

To sum up, not only the lack of available data but the complexity of the synergistic causal chains in multi-level community-based interventions makes it rather unfeasible to single out the specific size of the contribution to the suicide preventive effect of a certain measure in the entirety of the multi-level intervention.

See Viewpoint by Krysinska et al., 50(2): 115–118.