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INTRODUCTION:
Obesity rates have soared drastically in recent years and complications of obesity lead to increased health-care costs. Whether costs after colorectal surgery are specifically higher for obese patients has however not previously been assessed. The aim of this study was to compare direct costs for obese and non-obese patients undergoing colon resection.

METHODS:
All patients undergoing elective open partial colectomy at a single high-volume colorectal unit over the last 3 years were identified. Patients with metastatic malignancy were excluded. Patients were stratified based on increasing body mass index (BMI) and matched for age, gender and ASA class. Data relating to operation, length of stay (LOS) and complications and costs were compared. Subgroup analysis was performed on underweight and morbidly (BMI>40) obese patients.

RESULTS:
A total of 285 complete charts for patient undergoing partial colon resection were reviewed. Groups were similar with regards to age, gender, ASA class and procedure. Cancer and diverticulitis were the main diagnoses across all groups, except for the underweight group, where Crohn’s disease predominated and this group was excluded from further analysis. Mean LOS was similar between groups. Obese patients had greater mean hospital costs (\) than non-obese (\) but this difference was not significant (p=0.82). Wound infection rate approached 45% in the morbidly obese group and was only 8% in patients who were not obese. The overall morbidity, wound infection and costs progressively increased with increasing BMI (table). Morbidly obese patients had significantly increased overall morbidity and costs when compared to non obese patients (p=0.04).

CONCLUSION:
For patients undergoing elective colon resection, obesity leads to increased direct costs, with the morbidly obese having the greatest costs. The increased costs are likely due both to operating room costs and to the increasing higher overall morbidity, especially wound infection associated with increasing BMI. This risk should be accounted for in future health care policy including reimbursement and resource allocation strategies.

Group	Underweight (n=18)	Non Obese (n=185)	Obese (n=64)	Morbidly obese (n=18)
BMI (kg/m2)	<20	20-30	31-39	40-64
Age (years)	53	58.7	60.3	56.7
ASA class	1.7	2.3	2.5	2.6
Gender (% female)	55%	50%	55%	60%
Overall Morbidity	26%	35%	31%	72%
Wound infection	4%	8%	11%	44%
Total Direct Costs (\0	11450	12992	14803 (p=0.82)	18980 (p=0.04)
Nursing Costs (\0	2320	2498	3061 (p=0.02)	2903 (p=0.17)
OR costs (\0	678	1007	1127 (p=0.78)	2340 (p<0.01)
Pharmacy Costs (\0	972	751	1274 (p=0.09)	1307 (p=0.03)