Associations between frailty, depression and risk of hospitalisation for infection: A large prospective cohort study

There is a considerable lack of epidemiological evidence on whether frailty, and frailty comorbid depression could increase the risk of infections in older adults. This study aimed to examine the prospective association between frailty, depression, and risk of infections. A total of 308,892 eligible participants were included. Linked hospital admission records (HES) were used to identify a primary or secondary diagnosis of depression, and infection. Frailty was assessed by Fried frailty phenotype indicators. Cox proportional hazard model was conducted to examine the associated risk between frailty, depression, comorbid frailty and depression and risk of incident infections. Results were stratified by age and gender. During the follow-up, 74,749 (24.19 %) incident any infection cases were identified, the incidence density of any infection was 17.29/1000 person years. Frailty alone (HR = 1.38, 95 % CI: 1.33–1.43), depression alone (HR = 1.90, 95 % CI: 1.86–1.94), and comorbid frailty and depression (HR = 1.91, 95 % CI: 1.82–1.99) were associated with greater risks of any infections relative to participants with neither frailty nor depression. The associations between frailty alone, depression alone, comorbid frailty and depression, and any infections/most infection subtypes were significant for all age strata in both male and female. Frailty phenotype was assessed through the adapted Fried criteria, based on a mix of self-reported and objective measurements. Frailty, depression, and comorbid frailty and depression were significantly associated with increased risk of incident infections.