Probabilistic redistribution of ill-defined deaths reshapes Slovenia’s cause-of-death estimates

Nearly one in six deaths registered in Slovenia in 2021 was classified as ill-defined, meaning the underlying cause could not be precisely determined from the death certificate. In a new study published in Archives of Public Health, researchers applied a probabilistic redistribution approach to these deaths, reassigning them to specific causes of death and measuring how this changed the national picture of mortality. The work addresses a long-standing problem in mortality statistics: ill-defined deaths reduce the usefulness of cause-of-death data for public health and burden of disease analyses.

The study, led by Tina Lesnik with colleagues including Brecht Devleesschauwer, analysed all 23,261 registered deaths in Slovenia in 2021. Of these, 15.9 percent, or 3,701 deaths, were classified as ill-defined and were redistributed to specific causes. The underlying causes of death, coded according to ICD-10, were mapped to the Global Burden of Disease cause hierarchy list before redistribution was carried out.

The redistribution followed a modified probabilistic approach based on the Belgium Burden of Disease study, operating in three steps. The largest share of ill-defined deaths, 50.5 percent, was reassigned through package redistribution, followed by 31.0 percent through ICD-based redistribution and 18.5 percent through all-cause redistribution. Probabilities were estimated using Slovenian mortality data and Belgian multiple cause-of-death data from corresponding five-year reference periods, and uncertainty was assessed across 100 probabilistic iterations. Redistribution was performed at GBD Level 4 and presented at Levels 1 to 3.

The results show that redistribution primarily affected the magnitude of specific causes rather than their relative order. The ranking of leading causes of death remained largely unchanged across GBD levels. The greatest increase was observed for non-communicable diseases at GBD Level 1, while at Level 3, stroke, ischaemic heart disease, and several chronic conditions showed notable increases after redistribution. The contribution of the three redistribution steps varied across causes: ICD-based reassignment dominated for some causes, while package-based redistribution contributed substantially to others.

To test the robustness of the findings, the researchers performed a sensitivity analysis for 2019, the last full pre-pandemic year. This analysis showed a very similar distribution across the three redistribution steps and a stable ranking of the leading causes, suggesting that the approach behaves consistently across different mortality contexts.

The authors conclude that the probabilistic redistribution approach was successfully adapted to Slovenian mortality data and enabled more specific attribution of cause-specific mortality. Although redistribution had little effect on the ranking of leading causes, it substantially affected the magnitude of several causes and supports the inclusion of ill-defined deaths in national burden of disease assessments. The researchers note that these findings are particularly relevant for years of life lost estimation, where redistribution directly influences the quantified burden attributed to specific causes. Before this study, no redistribution of ill-defined deaths had been performed for Slovenia, and the potential impact on cause-specific mortality patterns remained unknown.

Subject of Research: Redistribution of ill-defined deaths in Slovenian mortality statistics using a probabilistic approach

Article Title: Adapting a probabilistic redistribution approach for Ill-defined deaths in Slovenia: implications for national burden of disease estimates

Article References: Lesnik, T., Eržen, I., Kragelj, L. Z., Scohy, A., Haneef, R., & Devleesschauwer, B. (2026). Adapting a probabilistic redistribution approach for Ill-defined deaths in Slovenia: implications for national burden of disease estimates. Archives of Public Health. https://doi.org/10.1186/s13690-026-02099-4

Image Credits: AI Generated

DOI: 10.1186/s13690-026-02099-4

Keywords: Slovenia, ill-defined deaths, cause of death, burden of disease, mortality statistics, probabilistic redistribution, ICD-10, Global Burden of Disease, years of life lost, non-communicable diseases, stroke, ischaemic heart disease