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 similar to 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 socioeconomic 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.