Background: Anecdotally, obesity adversely influences patient outcome following abdominal operations. However, recent studies have failed to conclusively support this widespread belief, and data regarding the true 30-day outcomes of obese patients undergoing colorectal surgery is lacking.
Methods: A prospective database was utilized to identify consecutive adult patients treated by experienced colorectal surgeons during a 9-month period. All intraperitoneal procedures were included. Operative summaries, clinic and hospital records were reviewed, and patients were stratified by body mass index (BMI). Outcomes were analyzed using Fisher's exact test and ANOVA, as appropriate.
Results: Of 528 eligible patients, 22.8% were obese (BMI > 30). Obese patients had increased incidences of diabetes and cardiovascular disease, while IBD was over-represented among those with BMI < 20. Laparoscopic conversion and transfusion rates, and ICU and hospital stays were equivalent among all groups. However, BMI was highly correlated with overall 30-day morbidity (Tables). When compared to non-obese patients, obesity produced significantly greater rates of intra- and postoperative technical (leak, dehiscence, reoperation), medical (MI, ARF, DVT), and infectious (abscess, wound or other infection) complications. Among 163 patients undergoing laparoscopic resections, there was no difference in overall complication rate for those with BMI > 30 relative to non-obese patients (29 vs. 32.6%, p=0.82). Following laparoscopic procedures, obese patients experienced significantly fewer complications than similar patients having open procedures (29 vs. 60.7%, p = 0.003).
Conclusions: Obesity is a significant risk factor for perioperative morbidity. Obese patients also pose a greater operative challenge, as evidenced by their increased rate of technical complications. However, there was no difference in BMI-stratified morbidity following laparoscopic procedures, suggesting laparoscopy by experienced surgeons can help to balance the risk inherent with obese patients.

	Obese	Non-obese	p-value
Medical	21.7%	12.5%	0.02
Technical	23.3%	15.1%	0.05
Infectious	32.5%	21.8%	0.03
Any complication	52.5%	35.2%	0.001

Body Mass Index	Complications/patient
< 20	0.91
20 - 25	0.79
25 - 30	0.98
30 - 40	1.21
> 40	2.00

p = 0.004