Age and sex differences in the annual and seasonal variation of Australia's suicide rate, 2000-2020

Suicide is a major public health concern both globally and in Australia. But in Australia the extent of substantive annual and seasonality trends since 2000 through the first two decades of the 21st Century, by age and sex, has not been formally reported. The current paper sought to identify annual and within-year (seasonality) trajectories in age-sex standardized suicide rates between 2000 and 2020. The annual and within-year (seasonality) trajectories of suicide were estimated from generalised regression analyses of Australia's mortality database. No systematic variation in Australia's suicide rate since 2000 was reported and was consistent between sex and age cohorts. Seasonal variation in rates were identified, with peaks in the new year (January), declines in late Summer/Autumn, stability in Winter, increases in Spring, but with a notable decline in early summer (November-December). These trends were driven men only. Interpretation of current suicide rates need to consider systematic long-term historical context. Despite a historical focus on youth suicide especially, working-aged and very old men have consistently reported higher standardized suicide rates over the first two decades of the 21st Century. Seasonal variation was reported but only reported by men, potentially because across the lifespan, suicide rates for females were a comparatively low incidence event. Particularly after recent successive national and international crises, we emphasise that surveillance and interpretation of current suicide rate requires careful consideration as to the extent any immediate variation may otherwise fall within otherwise normal historical norms.