Supplementary Material for: Predictive value of serum soluble ST2 in adult patients undergoing cardiac surgery for acute kidney injury

Introduction: Cardiac surgery is related to an increased risk of postoperative acute kidney injury (AKI). Serum soluble ST2 (sST2) is highly predictive of several cardiovascular diseases and may also be involved in renal injury. This study explored the relationship between serum sST2 levels measured at ICU admission and the development of AKI after cardiac surgery.
Methods: We prospectively conducted an investigation on consecutive patients who underwent cardiac surgery. sST2 was immediately measured at ICU admission. The relationship between the levels of sST2 and the development of AKI was explored using stepwise logistic regression.
Results: Among the 500 patients enrolled, AKI was observed in 207 (41%) patients. Serum sST2 levels in AKI patients were higher than those without AKI (61.46 ng/ml [46.52, 116.25] versus 38.91 ng/ml [28.74, 50.93], P < 0.001). Additionally, multivariable logistic regression analysis showed that as progressively higher tertiles of serum sST2, the odds ratios (ORs) of AKI gradually increased (adjusted ORs of 1.97 [95% CI, 1.13-3.45], and 4.27 [95% CI, 2.36-7.71] for tertiles 2 and 3, respectively, relative to tertile 1, P < 0.05). The addition of sST2 further improved reclassification (P < 0.001) and discrimination (P < 0.001) over the basic model, which included established risk factors.
Conclusion: Serum sST2 levels at ICU admission were associated with the development of postoperative AKI and improved the identification of AKI after cardiac surgery.