UNVGIB is a common and potentially life-threatening emergency. Currently, endoscopic hemostatic treatment has been a gold standard therapy for UNVGIB, which included endoscopic hemoclips, thermal therapy and injection therapy, alone or in combination with each other [18]. However, the total re-bleeding rate after endoscopic treatment was reported to 5%–20% [28–30]. So it is urgent to develop a more effective endoscopic device or technique for UNVGIB. Recently, the OTSC system, as novel management for GI bleeding, has drawn great attention in clinical practice. The OTSC system is a full-thickness suturing device designed for flexible endoscopy. It can be used to close the wound surface of target diseases, such as non-variceal GI bleeding, perforation, fistula, and anastomotic dehiscence [31]. At present, a number of studies reported the usefulness of OTSC system for UNVGIB. In this study, we combined the data from these reports, which allowed us to provide the best evidence on the effectiveness and safety of OTSC system for UNVGIB.
Our study demonstrated that the OTSC system was a technically feasible and effective (95.7% technical success rate and 84.2% clinical success rate) modality in achieving hemostasis of UNVGIB. The OTSC system was relatively safe with a tiny minority adverse events. The high clinical success rate and minimal complication profile indicated that the OTSC system was a viable method for patients with UNVGIB.
There was just one comparative study in our systematic review, which aimed to compare standard endoscopic treatment versus OTSC system [24]. It was demonstrated that OTSC system was associated with greater efficacy and lower re-bleeding rate when compared to standard therapy with through-the-scope clips in patients with recurrent peptic ulcer bleeding after successful initial hemostasis. So the authors favored the use of OTSC system for patients with recurrent bleeding of peptic ulcers. But we still can not reach the conclusion that OTSC system was superior to other endoscopic treatments for recurrent bleeding because of the limited data in our study.
Recently, a systematic review by Ofosu et al. reported a total of 16 studies which involved 475 non-variceal gastrointestinal bleeding patients treated with OTSC. In their report, the hemostasis rate achieved with primary application of OTSC was 93% (95% CI, 89%–96%). Similarly, the hemostasis rate achieved with rescue OTSC therapy was 91% (95% CI, 84%–95%). Re-bleeding rates after primary OTSC therapy were 21% (95% CI, 8%–43%) and 25% (95% CI, 17%–34%) with rescue OTSC therapy [32]. Our results were quite close to their report. We found the OTSC system applied as the primary treatment modality in 507 lesions, while 190 lesions as rescue treatment modality after previous endoscopic treatment failure. And most of those patients we included were at high risk of re-bleeding. Five of 15 studies emphasized the OTSC system could reduce significantly re-bleeding rates and mortality in high-risk cohort and could be a first-line treatment for UNVGIB [18, 20, 23, 25–26]. Conversely, some authors concluded that OTSC system might be considered as a secondary option for high-risk patients after conventional endoscopic hemostasis failed [16–17, 20–21]. Therefore, OTSC may be considered as first-line treatment for UNVGIB in high risk patients and rescue treatment for initial failed hemostasis with conventional endoscopic methods.
Seven of 16 studies in our systematic review reported the reasons for OTSC treatment failure: 1) delayed closure of OTSC occurring in lesions with large caliber artery and those with deep fibrotic base; 2) shallow placement of OTSC resulting from inadequate suction or premature clip deployment; and 3) misplacement of OTSC because of poor visualization, difficult anatomy, and unstable endoscope position [14, 16–17, 20–21, 25, 27]. These failure causes of OTSC above may enlighten its further application in future.
The safety of OTSC system for management of UNVGIB should be carefully assessed. Our study revealed that adverse events were rare. Just 2 of 16 studies reported 2 patients experienced the complications. Albert et al. reported one patient with duodenal oozing ulcer experienced a tiny GI leak which was suspected to be caused by the OTSC system, then the patients were converted to the surgical department [13]. Richter-Schrag et al. reported lumen obstruction after a duodenal OTSC application. Then, the obstruction released with 3 balloon-dilatations [20]. In addition, there were other OTSC-related complications reported in some studies when OTSC was applied for closure GI perforation or fistula, such as esophageal perforation, acute cholangitis, inadvertent tongue piercing and jejunal stenosis [33–36]. Our study showed 10.9% of patients died during the follow-up time. Although this data was surprising, only 3.9% patient died related to OTSC system application failure and most of these patients died due to fatal comorbidity. Gölder S. et al deemed that in case of severe recurrent bleeding, the bleeding source could be controlled by endoscopic treatment, but the patient refused any further therapy and died, which was one of the reasons for the high mortality [27].
While our study suggested a promising role of OTSC system for UNVGIB, further consideration is warranted regarding cost. In addition, clinical expertise and unfamiliarity among endoscopists in the small center may factor into variable technical and clinical success results. The expense of this modality for UNVGIB as well as availability remains unclear in our included studies. Future studies are needed to truly assess the cost-effectiveness of OTSC system placement for the management of UNVGIB.
Certainly, we recognized that some limitations in our study. First, our systematic review and meta-analysis were based completely and only on the published literature. We could not get the data of the individual patient, which would allow us to perform more detailed analysis, especially on whether application of the OTSC system as the primary therapy or the rescue therapy. Second, some included studies were missing data for our review variables of interest, such as bleeding classification, lengths of hospital stay and additional therapy modality. Finally, just one literature was high methodological quality study, and our review was lack of comparing OTSC system to other therapy modality.