Suicide time-series structural change analysis in Portugal (1913-2018): Impact of register bias on suicide trends.

BACKGROUND

Suicide is a potentially preventable cause of death. Epidemiology might help to identify death determinants and to monitor prevention strategies. Few studies address secular trends in suicide deaths, and even fewer describe trend-changes in relation to data collection/registration bias. Moreover, suicide is admittedly underreported. It is crucial to validate results in the context of other external causes of death trends, such as unintentional and undetermined intent deaths. We aimed to explore trends in suicide and other external causes of death in Portugal from the inception of registries until 2018, considering breaks in series.

METHODS

We collected data from all available official primary sources. We calculated cause-specific age-standardized death rates (SDR) by sex for ages equal or higher than 15 years with reference to the European Standard Population. We considered suicide (S), undetermined intent deaths (UnD), accidents (Accs), and all causes of death (ttMty). A time-series structural analysis was executed.

RESULTS

Suicide and other external causes of death rates were consistently higher in males than females. A global decline of deaths by suicide, undetermined intention and unintentional is observable. Breakpoints in years 1930, 1954, 1982, 2000-2001 were associated with major changes in deaths registration procedures or methodology.

CONCLUSIONS

The epidemiology of suicide in Portugal has changed over 106 years. However, adjusted data and consideration of bias reduce trends fluctuation. Trend changes are akin to specific changes in methodology of death registry. Suicide surveillance will improve with more reliable and stable procedures.