Short-term outcome of solitary kidney patients undergoing on-pump cardiac surgery

The outcome of patients with solitary kidney undergoing on-pump cardiac surgery is unknown. We sought to assess the in-hospital mortality and complications in these patients compared with patients with normal renal function.

This is a retrospective review of prospectively collected data over an 8-year period of all patients who underwent cardiac surgery. Our cohort consisted of 3363 consecutive patients divided into: solitary kidney (n=31, 0.9%) and normal kidneys (n=3332, 99.1%). Postoperative complications and in-hospital mortality were analysed.

Solitary kidney patients had higher incidence of renal failure (26% vs 5%, p-value<0.001), higher incidence of gastrointestinal complications (10% vs 1%, p-value 0.009) and higher blood transfusions (74% vs 43%, p-value<0.001) compared with patients with normal kidneys. There was an increased length of both intensive care unit stay (3.8 vs 2.2 days, p-value 0.031) and hospital stay (15.6 vs 8.5 days, p-value 0.026) among patients with solitary kidney compared with normal kidney patients. Multivariate analysis showed that solitary kidney is an independent predictor of postoperative renal failure (odds ratio (OR) 7.1 (95%CI 3.1-16.6)), gastrointestinal complications (OR 8.5 (95%CI 2.5-29.4)) and blood transfusion (OR 3.8 (95%CI 1.6-9.0)) after adjusting for age and gender. In-hospital mortality, however, was similar in both groups.

Although solitary kidney patients have similar short-term mortality as normal kidney patients, the rates of postoperative renal failure, gastrointestinal complications and blood transfusion are significantly higher among solitary kidney patients. Our findings have important clinical implications and prior knowledge of such entity with appropriate risk stratification at admission could help in reducing the risk of these potential complications.