Trends and Long-Term Mortality in Sepsis: Evidence from a Population-Based Retrospective Cohort Study of 13,994 Hospitalizations in the Abruzzo Region, Central Italy

Background: Sepsis remains a leading cause of morbidity, mortality, and healthcare expenditure worldwide. Despite international guidelines and diagnostic criteria, real-world variability in coding, treatment, and outcomes persist. This retrospective study analyzed 13,994 coded sepsis-related hospitalizations identified through administrative ICD-9-CM algorithms between 2016 and 2024 to evaluate the burden of sepsis, temporal trends, clinical outcomes, and healthcare costs within a regional health system. Methods: Hospitalization data across four local health authorities (ASL 201–204) over an 8-year period were analyzed. The coded sepsis cases were identified using validated ICD-9-CM-based algorithms and classified into four groups according to available microbiological coding: Gram-positive, Gram-negative, anaerobic and unspecified. Variables included patient demographics, length of stay, costs, outcomes (in-hospital and post-discharge mortality) and presence of septic shock. Comparative analyses were conducted using descriptive statistical methods and One-way ANOVA test and chi-squared tests were applied to evaluate the significance of differences. Multivariable logistic regression models were used to identify independent predictors of 6- and 12-month mortality. Results: The dataset included 13,994 coded sepsis-related hospitalizations, with the largest subgroup being ‘unspecified’ (48.0%). Among cases with specified etiology, coded anaerobic sepsis categories, though rare (0.7%), were associated with higher in-hospital mortality (45.5%) and economic burden (avg. € 8563). Mortality remained high at 6 and 12 months across all types, exceeding 50% post-discharge. Increasing age (OR ≈ 1.06 per year) and septic shock (OR ≈ 4.5–4.8) were the strongest independent predictors of mortality. Differences across microbiological groups should be interpreted cautiously given the high proportion of cases without organism-specific coding. Despite a modest reduction in mortality over time, sepsis was associated with persistently high 6- and 12-month mortality, highlighting a substantial long-term burden beyond the acute phase of illness. These findings suggest that sepsis-related hospitalizations are associated with substantial long-term mortality beyond the acute phase of illness. Discussion: These findings underscore the clinical and economic impact of sepsis in hospitalized patients, across microbiological coding categories. The high mortality rate at 6–12 months may support the need for further investigation into structured post-discharge follow-up strategies. Sepsis represents a substantial clinical and economic burden within the regional healthcare system, with persistently elevated short- and mid-term mortality. Incomplete organism-level documentation limits direct etiologic comparisons and highlights the need for improved integration between clinical, microbiological, and administrative data systems. Future research should integrate clinical variables and lab results to enable risk stratification and intervention planning.