Increased body mass index predicts increased blood loss during radical cystectomy

Historically obesity has been thought to impact negatively patients undergoing surgery. We evaluated the impact of body mass index (BMI), an objective measure of obesity, on operative and perioperative outcomes in patients undergoing radical cystectomy.

We reviewed the records of 304 consecutive patients who underwent radical cystectomy and urinary diversion between October 1995 and July 2000. Factors analyzed included BMI, clinical demographic characteristics, comorbidities, operative variables (eg estimated blood loss [EBL], transfusion requirement and operative time), length of stay and postoperative complications. Results were analyzed using the nonpaired heteroscedastic Student t test assuming unequal variances to determine statistical significance.

Of the patients 61% were overweight or obese (BMI 25 or greater). BMI did not correlate with type of urinary diversion, gender or race. On univariate analysis the preoperative variables age, American Society of Anesthesiologists score and BMI correlated with EBL. However, on multivariate analysis BMI was the only preoperative or operative variable that significantly correlated with EBL (p = 0.01). Mean EBL in patients with a normal BMI (less than 25) was 595 ml compared to the mean EBL for overweight and obese patients (25 or greater of 811 ml (p <0.001). However, BMI did not correlate with the complication rate or hospital stay.

On multivariate analysis considering preoperative and operative variables BMI was the only preoperative variable that predicted increased blood loss. Despite this finding overweight or obese patients in this series did not have a higher complication rate or longer hospital stay.