Development and validation of a preoperative "difficulty score" for laparoscopic transabdominal adrenalectomy: a multicenter retrospective study

Background: A difficulty score for laparoscopic adrenalectomy (LA) is lacking in the literature. A retrospective cohort study was designed to develop a preoperative “difficulty score” for LA. Methods: A multicenter study was conducted involving four Italian tertiary centers for adrenal disease. The population was randomly divided into two subsets: training group and validation one. A multicenter study was undertaken, including 964 patients. Patient, adrenal lesion, surgeon’s characteristics, and the type of procedure were studied as potential predictors of target events. The operative time (pOT), conversion rate (cLA), or both were used as indicators of the difficulty in three multivariate models. All models were developed in a training cohort (70% of the sample) and validated using 30% of patients. For all models, the ability to predict complicated postoperative course was reported describing the area under the curve (AUCs). Logistic regression, reporting odds ratio (OR) with p-value, was used. Results: In model A, gender (OR 2.04, p = 0.001), BMI (OR 1.07, p = 0.002), previous surgery (OR 1.29, p = 0.048), site (OR 21.8, p < 0.001) and size of the lesion (OR 1.16, p = 0.002), cumulative sum of procedures (OR 0.99, p < 0.001), extended (OR 26.72, p < 0.001) or associated procedures (OR 4.32, p = 0.015) increased the pOT. In model B, ASA (OR 2.86, p = 0.001), lesion size (OR 1.20, p = 0.005), and extended resection (OR 8.85, p = 0.007) increased the cLA risk. Model C had similar results to model A. All scores obtained predicted the target events in validation cohort (OR 1.99, p < 0.001; OR 1.37, p = 0.007; OR 1.70, p < 0.001, score A, B, and C, respectively). The AUCs in predicting complications were 0.740, 0.686, and 0.763 for model A, B, and C, respectively. Conclusion: A difficulty score based on both pOT and cLA (Model C) was developed using 70% of the sample. The score was validated using a second cohort. Finally, the score was tested, and its results are able to predict a complicated postoperative course.