Relationship Between Intensive Care Unit Length of Stay and One‐Year Mortality Following Cardiac Surgery

Background: Prolonged intensive care unit (ICU) length of stay (LOS) following cardiac surgery has been associated with higher resource utilization and increased in‐hospital mortality. Few reports have investigated the association between prolonged ICU LOS and subsequent mortality following hospital discharge. Methods: The relationship between ICU LOS and 1‐year all‐cause mortality was assessed in 2799 patients treated with coronary artery bypass grafting with and without concomitant valve surgery at a large tertiary center between January 1, 2017, and December 31, 2021. Multivariable logistic regression and Cox proportional hazards regression examined ICU LOS as a predictor of 1‐year mortality and to define the risk of mortality for ICU stays ranging from < 4 to > 14 days. Results: Patients ( N = 2799) included 76.1% males and 23.9% females aged 67.9 ± 9.9 years. Surgeries included isolated CABG (76.9%) and CABG with valve surgery (23.1%). Patients had a median ICU LOS of 1.93 days (IQR = 2.71), and 92 patients (3.3%) expired within 1 year of hospital discharge. ICU LOS was a significant predictor of 1‐year mortality (OR = 1.09, 95% CI = 1.06, 1.12, p < 0.001), while controlling for significant covariates. The prevalence of 1‐year all‐cause mortality progressively increased by ICU LOS cutoffs: < 4 days (1.9%), ≥ 4 days (7.2%), > 7 days (17.5%), and > 14 days (31.9%). Survival analysis further indicated that 1‐year mortality risk increased by ICU LOS cutoffs: ≥ 4 days (HR = 1.88, 95% CI = 1.19, 2.98, p = 0.007), > 7 days (HR = 3.80, 95% CI = 2.31, 6.25, p < 0.001), and > 14 days (HR = 10.15, 95% CI = 5.64, 18.25, p < 0.001). Conclusions: For each additional ICU day following CABG with and without valve surgery, the odds of 1‐year mortality increased by 9.0% when controlling for significant covariates. The risk of 1‐year all‐cause mortality increased by 88%, 280%, and 915% for ICU LOS ≥ 4 days, > 7 days, and > 14 days, respectively. These data indicate the need for more frequent postdischarge medical surveillance in patients with prolonged ICU stay.