Incidence and burden of hospitalizations for major respiratory infections among institutionalized adults followed by primary care residence units (UAR) in Madrid, Spain, September 2023–April 2025

Institutionalized older adults bear a disproportionate burden of severe respiratory infections, but population-based data from long-term care facilities remain limited. We quantified the incidence and economic impact of hospitalizations attributable to influenza, COVID-19, respiratory syncytial virus (RSV), and pneumococcal disease among residents covered by the Unidades de Atención a Residencias (UAR) in the Community of Madrid. We performed a retrospective, population-based study linking primary care records (AP Madrid) and hospital discharge data (CMBD) for 40,660 institutionalized adults followed by UARs between September 2023 and April 2025. Hospitalizations with a primary diagnosis of COVID-19, influenza, RSV, or pneumococcal disease were identified using ICD-10 codes. Crude and age- and sex-adjusted hospitalization rates per 100,000 person-years were calculated using the mid-period institutionalized population (July 2024) as denominator, with 95% confidence intervals derived by standard methods. Total hospital costs were estimated by multiplying hospital days by pathogen-specific daily cost values. A total of 2,555 respiratory hospitalizations were identified: 1,102 (43.1%) influenza, 1,003 (39.3%) COVID-19, 289 (11.3%) pneumococcal disease, and 161 (6.3%) RSV, mostly among residents aged ≥80 y (78.4%). Crude hospitalization rates per 100,000 persons were 1,724.1 for COVID-19, 1,310.9 for influenza, 356.6 for pneumococcal disease, and 231.2 for RSV; adjusted rates were 986.7, 932.0, 212.3, and 145.4, respectively. Total hospital costs reached €11.08 million. Institutionalized adults in Madrid experience high hospitalization rates and substantial economic burden from respiratory infections, particularly those aged ≥80 y, highlighting the need for enhanced preventive strategies in long-term care facilities.