Mid-urethral slings (MUS) are considered minimally invasive procedures with relatively low morbidity rate. However, a considerable number of patients after these operations report various undesired postoperative lower urinary tract symptoms (LUTS). Herein, urgency is considered the most bothersome with a significant impact on the patients’ post-operative satisfaction.  
Therefore, a hypothesis was tested if short-term solifenacin or mirabegron treatment could effectively decrease the percentage of patient suffering from urgency after MUS.

Consolidated Standards of Reporting Trials (CONSORT) criteria were followed for the description of this trial. The study protocol was approved by our local institutional ethical committee and all patients gave written informed consent before inclusion. Out of 718 patients with stress urinary incontinence treated in our department, 345 agreed to participate in this study. Women were eligible for the study if they had predominant symptoms of SUI with a positive cough test either in supine or standing positions at bladder volume approximately 250-300 ml, voiding frequency of 7 times or less per day, bladder capacity ≥250 ml, post-void residual (PVR) ≤ 50 ml without clinically relevant pelvic organ prolapse (POP-Q ≤1). Study exclusion criteria were the evidence of obstructed voiding in the absence of prolapse, severe comorbidities, and previous pelvic surgery. Patients were questioned before and after surgery for occurrence of storage symptoms (urgency, increased day time frequency, nocturia) as previously reported. Based on these criteria, the study was conducted on a group of 328 women who had underwent an ambulatory transobturator mid-urethral sling  (MUS) procedure with additional tape fixation as previously described. Before discharge, patients were assessed with ultrasonography (post void residual and tape position) and uroflowmetry to exclude the possibility of bladder outlet obstruction. Simple randomization was used from pseudorandom numbers computer-generated to allocate patients into the study groups in a ratio of 1:1:1. Two blinded investigators were not involved in the surgical procedures, but they were responsible for the randomization process. After randomization, 17 patients resigned from participation in this study: 5 from the control group, 1 from the solifenacin group and 11 from the mirabegron group. The remaining patients were then placed into 3 study groups: 
1. Without any additional treatment (control group, n=110),
2. Prophylaxis with 10 mg of solifenacin taken orally once daily for 4 weeks (n=114),
3. Prophylaxis with 50 mg of mirabegron taken orally once daily for 4 weeks  (n=104).
Follow-up visits were conducted by visis at site at one week and by phone-call survey 6 weeks after surgical intervention. 

Statistical analyses were performed with Statistica package version 12.0 (StatSoft Inc., Tulsa, OK, USA). A p value <0.05 was considered statistically significant. Chi-squared test was used as statistical test applied to sets of categorical data to evaluate how likely it is that any observed difference between the sets rose by chance. Interim analysis of data obtained from 65 patients in the control group and 56 in the treatment group showed that for urgency occurrence, 50 participants in each group would be enough to reach more than 95% power of chi2 at a 2-sided significance level of 0.05 for each group.

chi2 at a 2-sided significance level of 0.05 for each group.
Baseline demographic characteristics were similar between all study groups (Table 1).

The evolution of urgency after MUS in study groups is presented in Figure 1.

Both treatment options (mirabegron 50 mg and solifenacin 10 mg) significantly decreased the incidence of urgency at week 1 when compared to the control group. However, solifenacin was more effective in decreasing urgency at week 6 when compared to both mirabegron and control groups.

In the short-term follow-up period, we observed a significant decrease of urgency in women receiving either solifenacin or mirabegron.

Prophylaxis of undesired urgency after MUS with mirabegron or solifenacin can significantly improve patients’ satisfaction in the early postoperative period, still, solifenacin effect seems to be more prolonged.