Early impacts of the ‘National Suicide Prevention Trial’ on trends in suicide and hospital admissions for self-harm in Australia

Objectives: The National Suicide Prevention Trial was announced by the Australian Government in 2016 and aimed to prevent suicidal behaviour in 12 trial sites (representing a population of ~8 million). This study investigated the early population-level impact of the National Suicide Prevention Trial activity on rates of suicide and hospital admissions for self-harm in comparison to control areas. Methods: Relative and absolute differences in monthly rates of suicide and hospital admissions for self-harm were compared in the period after the National Suicide Prevention Trial implementation (July 2017–November 2020) to the period prior to implementation (January 2010–June 2017) in (1) ‘National Suicide Prevention Trial areas’ and (2) ‘Control areas’, using a difference-in-difference method in a series of negative binomial models. Analyses also investigated whether associations for suicide and self-harm rates differed by key socio-demographic factors, namely sex, age group, area socio-economic status and urban–rural residence. Results: There were no substantial differences between ‘National Suicide Prevention Trial areas’ and ‘Control areas’ in rates of suicide (2% relative decrease, relative risk = 0.98, 95% confidence interval = [0.91, 1.06]) or self-harm (1% relative decrease, relative risk = 0.99, 95% confidence interval = [0.96, 1.02]), adjusting for sex, age group and socio-economic status. Stronger relative decreases in self-harm only were evident for those aged 50–64 years, high socio-economic status areas, metropolitan and remote geographic areas. Conclusion: There was limited evidence that the National Suicide Prevention Trial resulted in reductions in suicide or hospital admissions for self-harm during the first 4 years of implementation. Continued monitoring of trends with timely data is imperative over the next 2–3 years to ascertain whether there are any subsequent impacts of National Suicide Prevention Trial activities.