Data extraction, data collection and scores computation
An evaluation of the data extraction procedure was performed to assess the agreement of two authors (EW and JG) on a subset of five randomly chosen papers. Subsequently, all data were extracted by one author (EW) using an electronic data capturing system developed using the Access 2016 desk application of Microsoft Office vers. 2010. Paper characteristics such as publication year, journal and study design along with the STROBE items scores were collected.
Several of the 22 STROBE items were further divided into components defined in the STROBE explanatory article 15 . For example, this article states for the 8th STROBE item (method assessment): “For each variable of interest, give sources of data and details of methods of assessment(measurement). Describe comparability of assessment methods if there is more than one group”. In this example, three specific sub-items in which the reporting of the features “sources of data”, “methods of assessment” and “comparability of assessment” were coded separately. Details regarding the 22 STROBE items and their sub-items are reported in Supplementary table 1. A four level grading system was used for the STROBE items and sub-items: “fully reported”, “not reported”, “reported by citation”, and “not applicable”. “Reported by citation” indicates that the authors referred to a citation implicating that this contains the full reporting for that given feature; however, we did not verify if this was the case by reading the referenced paper.