Impact of surgical volume and specialist availability on thyroidectomy outcomes in Brazil: an ecological study with a nationwide retrospective analysis of 230,345 cases (2008-2023).

Introduction: Thyroid disorders affect a significant proportion of the population and often necessitate surgical intervention, particularly in cases of malignancy. In this study, we analyzed thyroidectomy procedures performed within the public health system (SUS) of Brazil from 2008 to 2023, with a focus on factors influencing in-hospital mortality.

Methods: In the retrospective analysis, data on 230,345 thyroidectomies were extracted from SUS records and stratified by hospital volume and state-level distribution of head and neck specialists. Mortality rates were evaluated using non-parametric statistical analyses, including the Kruskal-Wallis and Spearman's correlation tests.

Results: The overall in-hospital mortality rate was 0.15%. States with fewer than 0.5 head and neck specialists per 100,000 inhabitants exhibited significantly higher mortality rates (0.2 versus 0.15, p = 0.02). Hospitals performing fewer than 25 procedures annually (very low-volume) had a fivefold increase in mortality compared with high-volume hospitals (0.51 versus 0.10, p < 0.001). When hospitals performing fewer than 10 procedures per year were excluded, significant differences in mortality among volume groups were no longer observed.

Conclusion: Mortality increased significantly in very low-volume hospitals performing fewer than 25 thyroidectomies per year; however, this difference was no longer observed after excluding hospitals that performed fewer than 10 interventions per year. These results support restricting thyroidectomies to hospitals performing at least 10 procedures annually and promoting centralization to improve outcomes. Structured regionalization policies are needed to ensure equitable access to specialized surgical care across Brazil.