Incidence of readmission to the ICU after cardiac surgery: a systematic review and meta-analysis

BACKGROUND: Due to the complexity of cardiac surgery, almost all patients need to be admitted to the intensive care unit (ICU) for postoperative care after surgery. After being discharged from the ICU, some patients need to be readmitted due to disease deterioration during hospitalization. We conducted a meta-analysis of the literature to investigate the incidence of readmission to the ICU in patients undergoing cardiac surgery. METHODS: The PubMed, Medline, and Elsevier databases were searched using the keywords “cardiac surgery,” “readmission,” “intensive care unit,” and “ICU” to retrieve English-language articles published from January 2000 to January 2021. The articles were screened, and their quality was evaluated. A meta-analysis was performed on the outcomes of patients after readmission to the ICU using Stata16.0 software. RESULTS: Ultimately, 9 articles were included in the meta-analysis, comprising 32,825 cardiac surgery cases, of whom 1,302 were readmitted to the ICU. The incidence of readmission to the ICU was 3.97%. Among the direct reasons for readmission to the ICU, respiratory failure accounted for 13.6–48.6%, while hemodynamic instability accounted for 21.6–51.9%. The results of the meta-analysis showed that the mortality rate of patients readmitted to the ICU was significantly higher than that of patients not readmitted to the ICU [risk difference (RD) =8.05, 95% confidence interval (CI): 5.10–12.69, Z=8.965; P<0.0001], as was the length of hospital stay [standard mean difference (SMD) =3.17, 95% CI: 1.40–4.94, Z=3.504; P<0.001], and the incidence of complications (odds ratio =1.97, 95% CI: 1.35–2.87, Z=3.507; P<0.001). CONCLUSIONS: Nine articles were included in this meta-analysis on the incidence rate of readmission to the ICU of patients undergoing cardiac surgery. The results showed that the proportion of readmission to the ICU was 3.97%. Patients readmitted to the ICU had a higher rate of complications, longer hospital stay, and higher mortality rate than those not readmitted.