Suicide is strongly associated with mental health and substance use disorders, which makes mental health- and substance misuse services important areas for suicide prevention. The aim of The Norwegian Surveillance System for Suicide in Mental Health and Substance Use Services is to describe all suicide deaths in Norway that occur within one year after contact with mental health and substance misuse services. The study uses a hybrid registry case series design. It consists of a yearly linkage between the Norwegian Cause of Death Registry and the Norwegian Patient Registry, which is linked with a questionnaire. The linkage is conducted by using a cryptographic hash function of the deceased's personal id, thus ensuring that the project can link data across sources without the use of directly identifiable information. This indirect linkage ensures the deceased's confidentiality. Moreover, the The Norwegian Surveillance System for Suicide shows how administratively collected data can be harnessed and used for surveillance. Both use of hybrid registry designs and linkage through cryptographic hash functions might contribute to the development of health informatics as well as quality improvement in health care.

Hanging is one of the most commonly used methods for suicide in both sexes worldwide. In a number of countries, hanging mortality has increased over the last decades. Nevertheless, there is a scarcity of studies that have explored the patterns and trends for mortality of suicide by hanging on global, regional and national levels, as most evaluations are limited to certain populations.

To assess the trends of suicide mortality by hanging, strangulation, and suffocation in Serbia, from 1991 to 2020.

This nationwide study, with epidemiological descriptive study design, was carried out based on official data. The age-standardized rates (ASRs, expressed per 100000 persons) were calculated by direct standardization, using the World Standard Population. Mortality trends from suicide by hanging were assessed using the joinpoint regression analysis: The average annual percent change (AAPC) with the corresponding 95% confidence interval (95%CI) was calculated. Age-period-cohort analysis was performed to address the possible underlying reasons for the observed suicide trends.

Over the 30-year period studied, there were 24340 deaths by hanging (17750 males and 6590 females) in Serbia. In 2020, the ASR of deaths by hanging was 4.5 per 100000 persons in both sexes together (7.6 in males vs 1.7 in females). The trends of suicide mortality by hanging decreased significantly between 1991 and 2020 in both males (AAPC = -1.7% per year; 95%CI: -2.0 to -1.4) and females (AAPC = - 3.5% per year; 95%CI: -3.9 to -3.1). Mortality rates of suicide by hanging had a continuously decreasing tendency in both sexes together in all age groups: The only exception was among males in 40-49 age group, with an increasing trend of suicide by hanging from 1991 to 2011 (by +0.3% per year).

The trends in suicide mortality by hanging have been decreasing in Serbia in the last three decades in both sexes, but this was more pronounced in women than in men. Despite the decreasing trends observed in mortality of suicide by hanging, further research is needed for better clarification of trends and help in suicide prevention in the future.

Aims: Future research on health inequality relies on data that cover life-course exposure, different birth cohorts and variation in policy contexts. Nordic register data have long been celebrated as a 'gold mine' for research, and fulfil many of these criteria. However, access to and use of such data are hampered by a number of hurdles and bottlenecks. We present and discuss the experiences of an ongoing Nordic consortium from the process of acquiring register data on socio-economic conditions and health in Denmark, Finland, Norway and Sweden. Methods: We compare experiences of data-acquisition processes from a researcher's perspective in the four countries and discuss the comparability of register data and the modes of collaboration available to researchers, given the prevailing ethical and legal restrictions. Results: The application processes we experienced were time-consuming, and decision structures were often fragmented. We found substantial variation between the countries in terms of processing times, costs and the administrative burden of the researcher. Concerned agencies differed in policy and practice which influenced both how and when data were delivered. These discrepancies present a challenge to comparative research. Conclusions: We conclude that there are few signs of harmonisation, as called for by previous policy documents and research papers. Ethical vetting needs to be centralised both within and between countries in order to improve data access. Institutional factors that seem to facilitate access to register data at the national level include single storage environments for health and social data, simplified ethical vetting and user guidance.