Impact of frailty on postoperative delirium in ICU patients aged 65 and older: a systematic review.

OBJECTIVES: The objective was to assess whether frailty is associated with an increased risk of postoperative delirium (POD) in intensive care unit (ICU) patients aged 65 years and older. DESIGN: A systematic review was conducted in accordance with Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. MEDLINE (via PubMed) and the Cochrane Library were searched for studies published between August 2014 and January 2025, assessing frailty with validated instruments and reporting POD during ICU stay. While the search strategy was not limited to a specific study design, only observational studies met the inclusion criteria. Study quality was appraised using the Newcastle-Ottawa Scale (NOS). Due to methodological heterogeneity, results were synthesised narratively. SETTING: This review targeted the intensive care setting specifically, including studies conducted in hospital-based ICUs in various countries. RESULTS: Of 655 records, five studies (n=3045) met inclusion criteria. Frailty prevalence ranged from 10% to 34.9%. Tools used included the Fried Frailty Scale, modified Frailty Index (mFI), FRAIL Scale (Fatigue, Resistance, Ambulation, Illnesses, and Loss of weight), Comprehensive Assessment of Frailty and Edmonton Frailty Scale. Frail patients had higher POD incidence and experienced more complications such as acute kidney injury, prolonged mechanical ventilation and reoperation. NOS scores ranged from 5 to 7, indicating moderate quality. CONCLUSION: Frailty appears to be associated with an increased risk of POD in ICU patients aged 65 and older. Given the limited number and heterogeneity of studies, further research is needed to validate this relationship and to inform targeted prevention strategies in critical care. TRIAL REGISTRATION NUMBER: https://doi.org/10.17605/OSF.IO/7TWQ8.