Serum creatinine and perioperative outcome--a matched-pairs approach using computerised anaesthesia records

A study was designed to utilise the resources of our computerised anaesthesia record keeping system to assess the attributable effects of increased preoperative creatinine (> 1.3 mg dL(-1)) on outcome in patients undergoing non-cardiac surgery.

This retrospective study was based on data sets of 58 458 patients recorded with a computerised anaesthesia record keeping system over a period of 4 yr at a tertiary care university hospital. Cases were defined as patients with a preoperative creatinine > 1.3 mg dL(-1); controls (creatinine < or = 1.3 mg dL(-1)) were selected and automatically matched according to several parameters (ASA physical status, high risk and urgency of surgery, age and gender) in a stepwise fashion. Main outcome measures were hospital mortality and the incidence of intraoperative cardiovascular events.

Three-thousand-and-twenty-eight patients (5.2%) had preoperative creatinine values > 1.3 mg dL(-1). Matching was successful for 54.5% of the cases, leading to 1649 cases (mean creatinine 3.3 +/- 2.2 mg dL(-1)) and 1649 controls (1.0 +/- 0.2 mg dL(-1)). The crude mortality rates for the cases and matched controls were 2.2% (n = 36) and 0.9% (n = 15), respectively (P = 0.003). Intraoperative cardiovascular events were found in 30.1% of the patients (n = 496) and in 28.3% of the matched controls (n = 466; P = 0.25, power = 0.46). Using logistic regression analyses a significant association between preoperative increased creatinine and hospital mortality was found (odds ratio 2.62; 95% confidence interval [1.39; 4.931).

An increased preoperative serum creatinine in patients undergoing non-cardiac surgery is associated with an increased perioperative risk, but not with a higher incidence of intraoperative cardiovascular events.