Effect of infections, DNA methylation and telomere length on frailty trajectories in hospitalized older patients: the INFRAGEN study protocol

Background: Infectious diseases are among the most common causes of hospitalization in older adults and may lead to a high burden on the individual’s health and healthcare system. However, it is unclear whether and to which extent these events might affect frailty, fastening its development or hampering its reversion. The aims of the INFRAGEN project are 1) to assess the impact of acute infections on frailty trajectories in older inpatients, and 2) to evaluate the modifying effect of sociodemographic, clinical, functional, and genetic/epigenetic factors on that association. Methods: INFRAGEN is a multicenter prospective observational study that will be conducted in the acute Geriatric Units of four Italian centers (Ferrara, Padova, Monza, and Napoli). The project will involve individuals aged ≥ 70 with no or mild-to-moderate pre-admission frailty (Clinical Frailty Scale [CFS] < 6) and diagnosis of acute infectious diseases at the time of hospital admission or during hospitalization. For each participant, we will record data concerning the multidimensional geriatric assessment and the type and severity of infectious diseases (diagnosed according to ICD-9 codes). Blood samples will be collected to assess Global DNA methylation, Leukocyte Telomere Length (LTL), and levels of circulating markers associated with biological processes related to frailty (inflammatory state, dysmetabolism, brain modifications, and oxidative stress). Frailty status will be evaluated through the CFS and Frailty Index at admission (referring to the 2 weeks before hospitalization), hospital discharge, and after 3 months. In a subsample, genetic/epigenetic analyses will also be performed at the 3-month follow-up. Discussion: INFRAGEN will contribute to exploring the complex pathophysiologic mechanisms of frailty in the context of infections in older adults through a translational approach. Trial registrations: NCT06430073 (ClinicalTrials.gov); Registration date: 2024–05-28.