Abstract
Background: Fragility fractures represent a significant public health burden, but the differential risks and costs across fracture types, particularly the interaction with patient age, remain poorly characterized in large-scale cohorts. This study aimed to evaluate the differential impact of fracture location and age on in-hospital mortality and healthcare costs within the Brazilian public health system. Methods: We conducted a retrospective cohort study analyzing 352,269 hospitalizations for fragility fractures from 2019 to 2023 using the Brazilian public health system's administrative database (DATASUS). Fracture types were categorized as proximal femur, hip/pelvis, humerus, vertebra, and forearm/wrist. Multivariable logistic and linear regression models were used to identify predictors of in-hospital mortality and costs, including an analysis of the interaction between age and fracture type. Results: The overall in-hospital mortality rate was 2.69%. Proximal femur (4.96%) and hip/pelvis (2.74%) fractures had the highest mortality rates, while forearm/wrist fractures had the lowest (0.12%). A significant interaction was found between age and fracture type (p<0.0001) ; for proximal femur fractures, each additional year of age increased mortality odds by 1.26%, compared to 0.76% for forearm/wrist fractures. Non-survivors incurred significantly higher median hospitalization costs (R 1,876.18vsR1,045.18, p<0.0001). Conclusions: Fracture location is a critical determinant of mortality and cost, with a synergistic, deleterious effect when combined with advanced age, especially for central fractures. These findings underscore the need for fracture-specific risk stratification models and targeted healthcare policies to mitigate the severe outcomes and economic burden of fragility fractures.