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Purpose: To determine whether different factors determine poor pouch-related outcomes after IPAA by the laparoscopic and open approaches.

Methods: Cohort study based on a prospectively collected database of IPAA patients operated from 1998-2010. Primary study outcomes were pouch failure and pelvic sepsis. Secondary outcomes were wound infection, small bowel obstruction and functional outcomes (bowel frequency and incontinence). Regression analysis evaluating the interaction of potential risk factors with operative technique (open vs. laparoscopic) was performed to identify differences in risk factors between the 2 techniques.

Results: Of 1962 patients, 224 (11.4%) underwent laparoscopic and 1738 (88.6%) open IPAA. Laparoscopic patients were younger (36 vs. 40 years, p=0.014), had lower BMI (25.3 vs. 26.3 kg/m2, p=0.004) with fewer ASA III patients (9.1% vs. 19.1%, p=0.003). Pouch failure was observed in 61 (3.1%) patients (laparoscopic: 2.7%, open: 3.2%, p=0.9). On multivariate analysis, no differences were seen in risk factors for pouch failure between laparoscopic and open IPAA. Increased ASA-classification was associated with a higher rate of pelvic sepsis after laparoscopic (p=0.017), but not open IPAA (p=0.51), this difference was statistically significant (interaction p-value=0.011). Body mass index (BMI) was an important risk factor for wound infection after both laparoscopic and open IPAA (p=0.035 and p<0.001, respectively). Surgeon, number of surgery stages and pulmonary co-morbidities were all associated with wound infection in open but not in laparoscopic surgery (table). Interaction analysis did not reveal significant differences for these factors. Diabetes mellitus was strongly associated with increased wound infection after open (p<0.001) but not laparoscopic IPAA (p=0.26). Interaction analysis suggested the presence of a difference between laparoscopic and open IPAA for this risk factor, although not statistically significant (interaction p=0.1). For functional outcomes, no differences were seen in risk factors for pouch failure between laparoscopic and open IPAA for both bowel frequency and incontinence after 3 years of follow-up.

Conclusion: Although risk factors for poor outcome after laparoscopic and open IPAA are largely similar, some differences do exist. In patients with a higher ASA grade, the laparoscopic approach is associated with a greater risk of pelvic sepsis after IPAA. However, patients with high risk of wound infection, e.g. diabetes, benefit from the laparoscopic approach since this may decrease the influence of predisposing risk factors. This novel analysis elaborating specific benefits of the two procedures will likely additionally help guide clinicians and patients decide upon the best approach when discussing the operative strategy prior to IPAA.

Comparison of risk factors between laparoscopic and open IPAA

	Pelvic sepsis			Wound infection
	Association with Lap (p-value)	Association with Open (p-value)	Interaction P-value*	Association with Lap (p-value)	Association with Open (p-value)	Interaction P-value*
Age at Surgery	0.103	0.294	0.25	0.630	0.0423	0.81
BMI	0.863	0.967	0.88	0.0350	0.00098	0.19
Diagnosis	0.765	0.0603	0.36	0.166	0.419	0.25
Duration of disease	0.838	0.500	0.65	0.178	0.498	0.29
ASA classification	0.0166	0.506	0.011	0.952	0.287	0.72
Surgeon	0.784	0.130	0.36	0.300	0.00285	0.9
Number of Surgery Stages	0.638	0.281	0.87	0.796	0.0110	0.86
Immunosuppressive drugs	0.566	0.174	0.31	0.283	0.793	0.35
Diabetes	0.227	0.583	0.28	0.264	0.00098	0.1
Cardiac co-morbidities	0.843	0.243	0.61	0.937	0.140	0.65
Pulmonary co-morbidites	0.749	0.0225	0.27	0.887	0.0102	0.33

ASA: American Society of Anesthesiologists. BMI: body mass index. IPAA: ileal pouch anal anastomosis. Lap: laparoscopic. * Due to the conservative nature of interaction analysis, the significance level used for identifying interactions was 0.10, which is warranted to achieve a prudent balance of probabilities between type I and type II errors.