Incidence, risk factors, and prognosis of a moderate increase in plasma creatinine early after cardiac surgery

Abstract

Objective: To evaluate the incidence and prognosis of a moderate increase in serum creatinine early after cardiac surgery.

Design: Retrospective clinical study.

Setting: Surgical intensive care unit in a university hospital.

Patients: Five hundred and ninety-one consecutive adult patients operated on for cardiac surgery during 1 year.

Interventions: Plasma creatinine was measured systematically before and during the first 3 days after surgery. Comorbid events were assessed as organ dysfunction (cardiac, pulmonary, hematologic, and neurologic), allowing us to calculate for each patient a dysfunction score (0-5).

Measurements and main results: Postoperative plasma creatinine increased by > or =20% in 15.6% of patients; eight of these required dialysis. A 20% increase in plasma creatinine was associated with other organ dysfunction in 79.3% of patients. Overall mortality rate was 2.7% and increased with the dysfunction score (17.7% for a dysfunction score > or =3). Mortality rate was 12.0% for patients who had 20% increased plasma creatinine with other organ dysfunction but was 0% for patients without other organ dysfunction. A logistic regression analysis revealed that the most important prognostic factors of death were cardiac dysfunction (odds ratio, 8.5; 95% confidence interval, 2.2-32.5) and the association of renal dysfunction and hematologic dysfunction (odds ratio = 12.0; 95% confidence interval, 3.9-37.2). Mean intensive care unit stay of patients with increased plasma creatinine was significantly longer (8.1 +/- 5.6 vs. 4.3 +/- 1.4 days, p <.01) and increased significantly with the dysfunction score (p <.01). Patients with isolated increased plasma creatinine had a significantly longer stay in the intensive care unit than patients without any organ dysfunction (4.6 +/- 1.4 vs. 3.9 +/- 0.9, p <.01).

Conclusion: Our results suggest that a postoperative 20% increase in plasma creatinine after cardiac surgery is not rare and has a significant impact on postoperative outcome, mainly when multiple organ dysfunction occurs. Any preoperative reduced renal reserve or perioperative renal ischemia increases the renal risk.