Acute Respiratory Infections Hospitalizations and In-Hospital Mortality in Ecuador: Differences in Patterns Between Pediatric and Adult Populations.

Background and Objectives: Acute respiratory infections (ARIs) remain a leading cause of hospitalization and preventable in-hospital mortality. This study aimed to characterize ARI hospitalizations and mortality in Ecuador and to identify factors associated with mortality across age groups. Materials and Methods: A cross-sectional study was conducted using national hospital data for 2015-2023. Crude hospitalization and in-hospital mortality rates were estimated by year and province. Age-adjusted temporal trends were evaluated using Joinpoint regression to obtain annual percentage change (APC). Univariable and multivariable logistic regression analyses were used to assess factors associated with in-hospital mortality in the overall, pediatric and adult populations. Results: A total of 576,195 ARI hospitalizations were analyzed: 51.24% were pediatric and 48.76% adult admissions. Although children accounted for most hospitalizations, in-hospital mortality was substantially higher among adults (14.04%) than among children (0.53%) and increased progressively with age. Age-adjusted rates had a significant annual increase among adults from 2015 to 2021 (APC 30.08% for hospitalization and 55.10% for mortality) and declined significantly from 2021 to 2023 (APC: -53.09% and -72.90%, respectively), whereas pediatric trends showed no significant changes. Lower respiratory tract infections, including bacterial pneumonia, viral pneumonia, and COVID-19, showed the highest odds of in-hospital death. Bronchiolitis was associated with increased odds of death in both pediatric and adult populations, with markedly stronger associations among adults. Rural residence and ethnicity showed age-specific associations with mortality, potentially reflecting differences in access to hospital care. During 2020-2021, COVID-19 accounted for 70.71% of ARI hospitalizations and nearly 87.17% of in-hospital deaths, with ARI hospitalization rates remaining above pre-pandemic levels thereafter. Conclusions: ARIs impose a substantial and unequal burden on Ecuador's health system. Mortality patterns may reflect age-related vulnerability, disease severity, and structural barriers to care rather than hospitalization volume alone, supporting the need for age-differentiated and equity-oriented public health strategies.