Development of an improved risk calculator for complications in proctectomy.

Background: Rectal surgery is associated with high complication rates, but tools to prospectively define surgical risk are lacking. Improved preoperative risk assessment could better inform patients and refine decision making by surgeons. Our objective was to develop a validated model for proctectomy risk prediction.
Methods: We reviewed non-emergent ACS-NSQIP proctectomy data from 2005 to 2011 (n = 13,385). Logistic regression identified variables available prior to surgery showing independent association with 30-day morbidity in 2010-2011 (n = 5,570). The resulting risk model's discrimination and calibration were tested against the NSQIP-supplied morbidity model, and performance was validated against independent 2005-2009 data.
Results: Overall morbidity for proctectomy in 2010-2011 was 40.2%; significantly higher than the 23.0 % rate predicted by the NSQIP-provided general and vascular surgery risk model. Frequent complications included bleeding (16.3%), superficial infection (9.2%), and sepsis (7.4%). Our novel model incorporating 17 preoperative variables provided better discrimination and calibration (p < 0.05) than the NSQIP model and was validated against the 2005-2009 data. A web-based calculator makes this new model available for prospective risk assessment.
Conclusions: We conclude that the NSQIP-supplied risk model underestimates proctectomy morbidity and that this new, validated risk model and risk prediction tool ( http://myweb.uiowa.edu/sksherman ) may allow clinicians to counsel patients with accurate risk estimates using data available in the preoperative setting.