Persistent critical illness and long-term survival in cardiac surgery: A multicentre cohort study

Background

Persistent critical illness (PerCI) is associated with poorer in-hospital outcomes in patients admitted to an intensive care unit (ICU), and in patients receiving cardiac surgery, yet its association with longer-term survival remains unclear.

Objective

We investigated the association between PerCI and long-term survival in patients receiving cardiac surgery.

Methods

In this retrospective, multicentre observational cohort study using the Australia and New Zealand Intensive Care Society Adult Patient Database, we included all adults (≥16 years) admitted to 83 ICUs across Australia and New Zealand after cardiac surgery (coronary artery bypass graft, valvular replacement, or both) from January 1^st 2018 to December 31^st 2022 for Australia and 31^st December 2020 for New Zealand. The primary outcome was survival time up to 4 years after ICU admission. We analysed the association between PerCI (defined as ICU length of stay ≥6 days) and survival time up to 4 years from ICU admission using a Cox proportional hazards model.

Results

We included 73,462 patients (90.8% elective, 9.2% emergent), of whom 5,087 (6.9%) developed PerCI. PerCI was associated with shorter survival times (hazard ratio [HR]: 3.14, 95%-CI: 2.77–3.55). As ICU stays became progressively longer, survival times progressively decreased (HR by additional day in ICU: 1.02, 95%-CI: 1.01–1.03). PerCI was associated with larger reductions in survival times in patients aged <65 years (HR: 5.61, 95%-CI: 4.72–6.67) compared to patients ≥65 years (HR: 2.83, 95%-CI: 2.48–3.23, p-interaction <0.0001). However, there were no significant differences amongst the various types of surgeries, and between elective and emergent surgeries.

Conclusion

PerCI was associated with poorer outcomes, and this persisted during longer-term follow-up. Further study is required to identify potential modifiable risk factors for PerCI.