Doppler ultrasound values after liver transplantation in children and their association with graft outcomes: a protocol for a systematic review and meta-analysis

INTRODUCTION: Liver graft and patient survival in children have improved substantially over the years; nevertheless, graft-related complications persist as the most important risk factor for mortality and graft loss. Doppler ultrasound evaluation is routinely used after liver transplantation; however, there is no consensus defining normal values, timing or frequency of Doppler ultrasound postoperative evaluation. Identification of patients who require an intervention or change in postoperative management is therefore challenging. METHODS AND ANALYSIS: We will conduct a systematic review and meta-analysis to appraise and synthesise evidence describing Doppler ultrasound measurements and their association with graft complications in children who have received a liver transplant. We will search multiple databases: Ovid Medline, Embase, Wiley Cochrane Library, Web of Science—Science Citation Index Expanded, trial registry records and meeting abstracts using a combination of subject headings and keywords for liver transplantation, Doppler ultrasound and paediatric patients. All identified titles and abstracts of studies will be assessed for potential relevance. Selected studies will be retrieved and subjected to a second phase of screening, both selection phases will be done in duplicate by two independent reviewers, and discrepancies will be documented and resolved by a third reviewer. Data extraction will be done independently by two reviewers using a standardised data extraction form. Quality of evidence and risk of bias will be assessed, synthesised and pooled for meta-analysis if possible. We will perform a subgroup analysis if enough data are available. ETHICS AND DISSEMINATION: Strategies to disseminate our review include presenting in liver transplant review sessions, publishing in high-impact peer-reviewed medical journals, and presenting at national and international paediatric radiology and liver transplant meetings, conference presentations, events, courses and plain-language summaries. This knowledge will allow easier identification of patients with a higher risk of developing graft-related complications and could potentially improve patient and graft outcomes. We wish to disseminate our results to discover potential areas for future research and drive improved future practices and policies. Our target audience includes researchers, institutions, healthcare professionals, health system decision-makers, policy-makers and research funders community. TRIAL REGISTRATION NUMBER: CRD42019119986.