2.1.3. Study Selection

Following the removal of duplicate references, two reviewers (M.C. and F.C.) independently assessed the eligibility of each of the remaining pre-selected references by screening the titles, keywords and abstracts according to the systematic review eligibility criteria. The reviewers subsequently and independently assessed the full texts of all potentially relevant references for their eligibility. Following selection, discrepancies between the reviewers were resolved by discussion, and, when a consensus could not be reached, a final decision was taken by majority after consultation with the senior reviewer (L.G.). Multiple publications reporting on the same study were jointly analyzed as reporting one study. Reference lists of full-text articles were hand-searched to identify relevant publications that were missed.

The inclusion criteria for study selection were systematic reviews and meta-analyses including only RCTs investigating the role of TCS in abdominal surgery. We also searched for additional RCTs that were not included in the meta-analyses published between January 2013 and June 2019. The exclusion criteria were meta-analyses of studies that investigated operations other than, or not only, abdominal surgery, as well as observational studies. The most recently available meta-analysis that fulfilled the selection criteria was then critically appraised. The Appendix A table reports the list of all other published meta-analyses on TCS that were excluded from this study since they were not in line with the above-mentioned inclusion criteria.

### 2.1.4. Data Extraction and Management

Data extraction was performed in a standard electronic spreadsheet, with the reviewers independently extracting the data from all eligible articles. Extractions were compared and disagreements resolved by discussion or by consultation with a third reviewer. The following data and information were extracted: year of publication, number of studies included, number of patients included in the two groups, and outcome measurements (overall SSI risk including relative risks (RR), odds ratios (OR), 95% confidence intervals (CI), and all possible sources of bias).

### *2.2. Budget Impact Model*

The economic model was developed in Microsoft ® Excel and used to perform a budget impact analysis in accordance with the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) guidelines "Principles of Good Practice for Budget Impact Analysis" [30,31]. This analysis evaluated the impact of introducing TCS as an alternative to conventional sutures (CS), for the prevention of SSIs from an Italian hospital perspective, and more specifically from a general surgery unit. The model compared the incremental cost of adopting the technology with the potential savings derived from the reduction of SSI incidence on the total number of performed abdominal procedures. The model output consisted of a net potential saving for the surgery that was achievable by a total conversion from CS to TCS and a reduction of SSI episodes.
