Predicting long-term risk of reoperations following abdominal and pelvic surgery: a nationwide retrospective cohort study

Abstract

Background: The risk of reoperations after abdominal and pelvic surgery is multifactorial and difficult to predict. The risk of reoperation is frequently underestimated by surgeons as most reoperations are not related to the initial procedure and diagnosis. During reoperation, adhesiolysis is often required, and patients have an increased risk of complications. Therefore, the aim of this study was to provide an evidence-based prediction model based on the risk of reoperation.

Materials and methods: A nationwide cohort study was conducted including all patients undergoing an initial abdominal or pelvic operation between 1 June 2009 and 30 June 2011 in Scotland. Nomograms based on multivariable prediction models were constructed for the 2-year and 5-year overall risk of reoperation and risk of reoperation in the same surgical area. Internal cross-validation was applied to evaluate reliability.

Results: Of the 72 270 patients with an initial abdominal or pelvic surgery, 10 467 (14.5%) underwent reoperation within 5 years postoperatively. Mesh placement, colorectal surgery, diagnosis of inflammatory bowel disease, previous radiotherapy, younger age, open surgical approach, malignancy, and female sex increased the risk of reoperation in all the prediction models. Intra-abdominal infection was also a risk factor for the risk of reoperation overall. The accuracy of the prediction model of risk of reoperation overall and risk for the same area was good for both parameters ( c -statistic=0.72 and 0.72).

Conclusions: Risk factors for abdominal reoperation were identified and prediction models displayed as nomograms were constructed to predict the risk of reoperation in the individual patient. The prediction models were robust in internal cross-validation.

Figure 1

Reoperations per surgical area.

Figure 2

Nomogram to calculate the risk for reoperation overall. By drawing a vertical line from each variable to the point axis on top and summing the individual points for all variables, the total score is calculated. From the total score axis perpendicular to the bottom, the linear predictor and the 2-year and 5-year risk for reoperation are determined. An example of a calculation using the nomogram (Fig. 2); male patient, 50 years old (23 points), laparoscopic (0 points) right hemicolectomy (colon 71 points) due to malignancy (14 points) as initial surgery (taken the highest surgical area, seen right hemicolectomy is performed in right upper quadrant (55 points) and right lower quadrant (16 points). Summed up a total of 179 points, translating to a 14% risk for reoperation in 2 years postoperative and an 18% 5-year risk. GI, gastrointestinal; IBD, inflammatory bowel disease.

Figure 3

: Nomogram to calculate the risk for reoperation later than 30 days in the same area. By drawing a vertical line from each variable to the point axis on top and summing the individual points for all variables, the total score is calculated. From the total score axis perpendicular to the bottom, the linear predictor and the 2-year and 5-year risk for reoperation are determined. GI, gastrointestinal; IBD, inflammatory bowel disease.