Predictive factors of low anterior resection syndrome following anterior resection of the rectum.

Objective: to identify predictors of low anterior resection syndrome (LARS) that can contribute to its early diagnosis and treatment. Methods: we conducted a retrospective cohort study of patients undergoing anterior resection of the rectum between 2007 and 2017 in the Coloproctology Service of the Federal University of Parana Clinics Hospital. We performed Receiver Operating Characteristic Curve (ROC) analysis to identify LARS predictive factors. Results: we included 64 patients with complete data. The men's age was 60.1±11.4 years and 37.10% were male. Twenty patients (32.26%) had LARS. The most reported symptoms were incomplete evacuation (60%) and urgency (55%). In the univariate analysis, the distance from the anastomosis to the anal margin (p<0.001), neoadjuvant therapy (p=0.0014) and ileostomy at the time of resection (p=0.0023) were predictive of LARS. The ROC curve analysis showed a 6.5cm cut-off distance from the anastomosis to the anal margin as a predictor of LARS. Conclusion: distance between the anastomosis and the anal margin, neoadjuvant therapy history and preparation of stoma are conditions that can help predict the development of LARS. Guidance and involvement in patient education, as well as early management, can potentially reduce the impact of these symptoms on patients' quality of life.

Despite the evolution of the surgical technique and concern with the preservation of pelvic innervation, many patients develop severe urinary, sexual and intestinal alterations after anterior rectal resection (ARR). These changes are referred to as Low Anterior Resection Syndrome, or LARS 3 .

Symptoms of LARS include increased
bowel movement frequency, stool of liquid consistency, fecal impaction, urgency, and fecal incontinence. These may occur in up to 80% of post-ARR cases 4 . Symptoms appear shortly after the intestinal transit is restored, are more intense in the first months, and may improve in the first two years, when they reach stability and become a chronic condition 5 .
The diagnosis of LARS is predominantly clinical and to assess functional outcomes after ARR, tools are commonly used to evaluate fecal incontinence, given the impact of this symptom on the patient's quality of life, such as the Wexner-Jorge score 6 . Two tools were introduced in an attempt to identify and quantify the impact of

Original Article
Predictive factors of low anterior resection syndrome following anterior resection of the rectum. Initially, we selected 110 patients whose operation was rectosigmodectomy. We excluded 48 patients, 33 because they underwent procedures other than those registered and 15 that met the exclusion criteria adopted: permanence of the transit-deriving stoma, incomplete medical records, inflammatory bowel disease, Hirschsprung's disease, and early pelvic recurrence of the rectal tumor ( Figure 1).
To assess the possible interference of comorbidities on the incidence of LARS, we used the Charlson Comorbidity Index (CCI) 9 . We considered the surgical description report to identify the type of surgery performed and the distance from the anastomosis to the anal margin. To evaluate TNM staging 10  to identify the distance from the anastomosis to the anal margin that was predictive of LARS symptoms.
We considered a significance level of 5% for this study.

RESULTS
Of the 62 patients included, 39 (63%) were female. The average age was 60.1 years, ranging from 33 to 85. The average distance from the anastomosis to the anal border was 9.57cm, ranging from 2,0 to 15 cm (Table 1). The diseases that led to the anterior resection with urinary symptoms and only one patient (5%) with complaints related to sexual function ( Table 2).
The most common cause leading to anterior resection of the rectum was malignant neoplasia, in 42 patients (67%), followed by diverticular disease, in ten (16%), and chagasic megacolon, in five (8%).
Of the patients with neoplasia, the most common locations were in the middle rectum, distal sigmoid and proximal rectum, with 34%, 31% and 22%, respectively.    Similar to what other studies have reported [16][17][18] , we found no statistical significance between the incidence of LARS and gender, although Liu et al. 19 reported being female as an independent risk factor for the syndrome and Gadan et al. 20 15 and from Ekkarat et al. 16 . Because this average age is associated with comorbidities due to aging, we performed the risk assessment of developing LARS with the CCI index 9 . There was no statistical significance between them. We found no other reports in the literature.   The mechanism seems to be related to direct nerve damage and pelvic fibrosis induced by pelvic irradiation. This treatment can also cause sexual and urinary dysfunction due to nerve damage 25 .