To assess the current evidence on the effectiveness and safety of Contasure-Needleless (C-NDL) versus transobturator (TOT/TVT-O) slings in the management of female stress urinary incontinence (SUI).

A comprehensive literature review of articles that investigated the efficacy and safety of C-NDL and TOT/TVT-O was performed based on studies published before June 2019 and retrieved from PubMed, Embase, CNKI and the Cochrane Library. Two reviewers searched the literature, independently extracted the data and evaluated the quality of the data according to the inclusion and exclusion criteria. A meta-analysis was performed by using Review Manager 5.3 software.

Nine studies with 1349 SUI female patients were included. Our meta-analysis showed that C-NDL has a noninferior clinical efficacy compared with TOT/TVT-O with respect to the subjective cure rate [OR = 0.81, 95% confidence interval (CI) (0.58 to 1.14), p =0.23] and objective cure rate [OR = 0.82, 95% CI (0.57 to 1.17), p = 0.27]. In addition, C-NDL is associated with an obviously shorter operative time [mean difference (MD) = -6.94, 95% CI (-10.66 to -3.22), p = 0.0003]. In terms of the postoperative visual analogue scale (VAS) and the incidence of postoperative pain, C-NDL has a greater advantage [MD = -1.71, 95% CI (-2.91 to -0.50), p = 0.005]; [OR = 0.21, 95% CI (0.05 to 0.96), p = 0.04]. There was no statistically significant difference in the rate of complications found between the two groups except for that of groin pain.

The most important indicators for evaluating efficacy are the subjective and objective cure rates. The tension provided by the tape support plays a significant role in the efficacy and is associated with the cure rate and necessity of re-surgery. Some SIMS procedures have been performed in clinical practice to evaluate the efficacy. The meta-analysis compared the TVT-Secure, Mini-Arc and Ophira together with standard midurethral slings, and the result showed an inferior cure rate for these SIMSs. An animal trial reported that with the highest surface area to counteract extraction, the anchor of C-NDL has the highest mean immediate extraction forces compared with those of other SIMSs. Relative to other SIMSs, the C-NDL has a greater contact area and is more similar to the standard sling, which ensures sufficient firmness. Based on our meta-analysis, no significant differences were found in the comparison of subjective and objective cure rates. In addition, the incidence of repeated SUI surgery was not obviously different between the C-NDL and TOT/TVT-O groups. Apart from the investigation of Bakay et al., the follow-up time of the other included studies is longer than 12 months. Therefore, the results also confirmed that the tension of C-NDL is not inferior to that of TOT/TVT-O and that the mid-term efficacy of C-NDL is reliable. Until now, due to the short period of C-NDL use, the long-term efficacy still needs more high quality RCTs to verify.
Our meta-analysis showed that the patients who underwent C-NDL had a shorter operation time, which confirmed the previously published outcome. In addition, the pooled results showed that patients receiving C-NDL presented improved postoperative pain and postoperative VAS scores. In particular, groin pain greatly improved. These results are consistent with those of Kim’s study, which reports that SIMSs are superior with respect to immediate postoperative pain. The difference may be explained by the surgical procedure. Similar to other SIMSs, the C-NDL is inserted through a single vaginal incision and blindly avoids the retropubic space and obturator foramen. The pain occurrence is related to the fact that there is no incision in the groin area, the sling does not reach the groin, and there is no foreign body sensation. The surgical routine also decreased the risk of blood vessel and nerve injury, which was in line with our present analysis. In Baya’s study with a three-year follow-up, there were no cases of groin pain, and only one patient had a mild haematoma. In addition to the cure rate, postoperative pain also plays an important role in patient satisfaction. In a study by Schellart et al., patients with SUI were willing to accept a relatively lower cure rate with a less invasive procedure in order to avoid postoperative pain. Therefore, with a high efficacy and less pain, it seems that C-NDL is a better choice to manage SUI in patients. 
With respect to the hospital stay, a previous meta-analysis showed that SIMSs involve a shorter hospitalization time than that for transobturator slings. However, our results showed no significant differences in hospital stay between the two groups. According to our clinical experiences, the hospital stay might be associated with the patients' baseline basic characteristics and with hospital conditions, which are affected by human factors. In addition, the inpatient stay was arranged for 1 to 2 days, which also indicates that C-NDL yields a faster recovery rate, which indicates enhanced recovery after surgery.

Our data suggest that C-NDL is an effective method for treating female SUI. Compared to TOT/TVT-O, C-NDL is associated with a shorter operative time, and the incidence of postoperative pain is obviously decreased. In addition, both methods have proven to be safe. Nevertheless, these findings should be further confirmed through large-volume, well-designed prospective randomized controlled trials (RCTs) with extensive follow-up.