Most Hospital-Acquired Complications among Older Adults Are Associated with Frailty: The South-Western Sydney Frailty and Hospital-Acquired Complications Study

Background: People live longer, and frailty has become an important problem in the acute hospital setting. Increasingly the association between frailty and hospital-acquired complications has been reported. However, the overall burden of frailty in this setting has not been described. Therefore, we undertook this study to describe the association between frailty and the risk of hospital-acquired complications among older adults across our five acute hospitals and to estimate the overall burden of frailty attributable to these complications.

Methods: Consecutive admissions among women and men aged ≥ 65 years across our local health district's five acute hospitals, between January 2010 and December 2020, were included to investigate the association between the number of cumulative frailty deficit items and hospital-acquired complications and infections. The numbers of cumulative frailty deficits are presented in four groups (0-1 item, 2 items, 3 items, and 4-13 items). Individual events such as falls, delirium, pressure injuries, thromboembolism, malnutrition, and multiple types of infections are also presented. The overall burden of frailty was estimated using a population-attributable-risk approach.

Results: During the study period there were 4,428 hospital-acquired complications, among 120,567 older adults (52% women). The risk of any hospital-acquired complication (HAC) or any hospital-acquired infection (HAI) increased as the cumulative number of frailty deficits increased. For the 0-1 deficit item group versus the 4-13 items group, the risk of any HAC increased from 5.5/1000 admissions to 80.0/1000 admissions, and for any HAI these rates were 6.2/1000 versus 58.2/1000, respectively (both p-values < 0.001). The 22% (27,144/120,567) of patients with 3 or more frailty deficit items accounted for 63% (2,774/4,428) of the combined hospital-acquired complications and infections. We estimated that the population-attributable risks of any hospital-acquired complication or infection were 0.54 and 0.47, respectively.

Conclusion: We found that an increasing number of cumulative frailty deficit items among older patients are associated with a higher risk of hospital-acquired complications or infections. Importantly, frail older adults account for most of these adverse events.