Trial design
This was a multicenter, prospective, randomized, open, clinical trial. The study protocol was registered at ClinicalTrials.gov ID, NCT02977585, “Helmet Study”. The Bambino Gesù Hospital Ethics Committee approved this study (protocol number 1239_OPBG_2016). The Institutional Ethics Committee of each study site approved the study protocol. The Consolidated Standards of Reporting Trials (CONSORT) checklist was followed. The study was interrupted after the enrollment of the first 127 patients due to a low enrollment rate.