Review articleEffectiveness of suicide prevention interventions: A systematic review and meta-analysis
Introduction
Suicide is a worldwide major public health problem, with 800,000 suicides annually [1]. Suicide attempts are among the most important known predictors of completed suicides, and occur even more often [1,2]. Since the 2013 commitment of the World Health Organisation Member States to work towards suicide prevention [3], ample national strategies and suicide prevention interventions have been developed and overviews of them provided in systematic reviews [[4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17]]. The effectiveness of suicide prevention interventions in reducing suicide rates is found in certain settings, but not (yet) in others [4,8,11,12]. In 2005, Mann et al. performed a systematic review pertaining to suicide prevention strategies in general [18]; this review was updated by Zalsman et al. [4]. Despite growing evidence for the effectiveness of several suicide prevention strategies, until now a comparative estimate for the effect of different types of interventions has not yet been provided. Also, it remains unclear which strategy is the most effective and if the setting of intervention is relevant to the effect.
It has been argued that effective action towards reducing suicide would need combined interventions by different providers in multiple domains [3,4,18] – so-called multilevel interventions [19,20]. For example, at the community level, this could be accomplished by: (1) providing gatekeepers such as teachers and with priests training others to aid recognition of persons potentially at risk; (2) combining it with a publicity campaign [21,22] and with (3) instructions to the press on how to publish information on suicides. In addition, on the primary care level, general practitioners could be trained on how to address suicidal thoughts and behaviour in patients. Indications of the effectivity of multilevel interventions were found in non-controlled studies [20,23,24]; however, this effect was not replicated in one of the very few published randomised controlled trials examining the effectiveness of a multilevel intervention in preventing suicidal behaviour [22].
Multilevel interventions have been suggested as having synergistic potential [19], meaning that the effect of the combined parts of the intervention might create a stronger effect than the sum of the individual effects of the interventions. Hegerl et al. observed, during the implementation of a four-level community-based suicide prevention intervention, that general practitioners were more motivated to participate in the training sessions because the ongoing public campaign aimed at destigmatisation prompted their patients to present themselves with possible depressive symptoms and suicidal ideation [24]. Synergistic interactions between intervention levels were also suggested by a qualitative study on multilevel suicide prevention interventions in four European countries [25]. However, thus an estimate of a possible synergistic effect has not been provided [19,20].
This study has three objectives:
- 1.
To establish an estimate of the effect of suicide prevention interventions for completed suicides and suicide attempts;
- 2.
To explore if the setting of intervention is associated with different effect sizes;
- 3.
To explore if multilevel interventions have synergistic effects.
Section snippets
Protocol and registration
The study protocol is registered in PROSPERO, the international prospective register of systematic reviews of the University of York (www.crd.york.ac.uk/prospero/) and is accessible under ID number CRD42018094373. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement for transparent reporting was followed [26]. The PRISMA checklist is included in Appendix 1.
Eligibility criteria
Studies were considered eligible if suicides and/or suicide attempts were included as an outcome and if
Study selection
The database search identified 442 records. In addition, 172 records were identified by consulting suicide prevention experts (19 records) and by identifying studies from literature reviews about suicide prevention interventions (153 records). After removal of duplicates, 447 records remained. After screening the records on title and abstract, 389 records were excluded and 58 articles were assessed for eligibility based on the full text (46 through database searching and 12 through additional
Discussion
The aim of this review was to evaluate the effectiveness of suicide prevention interventions in different settings, to compare their relative effectiveness by providing an estimate of their effect size, and to explore possible synergism of multilevel interventions in a meta-analysis. This systematic review includes 252,932 participants in 16 controlled studies. The meta-analysis, for the first time, provides a comparative estimate for the effect of different types of suicide prevention
Contributors
EH and CFC designed the study. EH, DÖ and CFC performed the systematic review and data extraction. ChvN and MB assessed the risk of bias of individual studies. CFC performed the meta-analysis. EH and CFC wrote the first draft of the paper, and ChvN, MB, IE, SdJ, and DÖ contributed in the process of drafting and revising. All authors gave their agreement and approval for all aspects of the final version of the paper.
Declaration of interests and funding
The authors declare no competing interests. The authors of this study had full access to all the data in the study and had final responsibility for the integrity of the data, the accuracy of data analysis and the decision to submit for publication. This research was funded by the Netherlands Organisation for Health Research and Development, grant number 537001002. The funder had no role in study design, data collection, data analysis, data interpretation, or writing of the report.
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