Dietary recommendations should be based on scientific evidence, and ideally, systematic reviews (SRs) are conducted as part of the guideline development process. The usability of SRs for decision-making is primarily determined by the quality of the evidence from available primary studies, as well as the quality of the SRs themselves. A comprehensive SR protocol ensures high-quality implementation and minimises bias, while making these protocols publicly accessible, promotes transparency and prevents redundancy. The PROSPERO database offers valuable insights into planned methodologies. The aim of this study is to investigate the completeness of reporting in SR protocols for diet- or nutrition-related trials, determine how this has changed over time, and examine the publication of completed SRs by comparing their content with those described in the corresponding protocols.

We developed a systematic search strategy for PROSPERO to identify nutrition- or diet-related SR protocols registered at two different time points (2019 and 2024). Following a screening process to identify eligible protocols, relevant predefined data will be extracted. Subsequently, a structured search will be conducted to identify potential journal publications of the selected protocols, as well as publications describing the results of the SRs, from which relevant predefined data will be also extracted. The methodology of the published articles will be compared with the corresponding a priori protocols registered in PROSPERO. The PROSPERO records registered in 2019 will be compared with those registered in 2024. The results will be evaluated by descriptive statistics, the reporting completeness of PROSPERO records will be assessed based on Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P), the planned use of any approaches to assess certainty of evidence will be investigated, and the adherence of published SRs to the methodological details outlined in their corresponding PROSPERO entries will be examined.

Since both databases and publications used in this study are publicly available, ethical approval is not required. Results of the study will be submitted for publication in an international, peer-reviewed journal.

The present study has previously been registered with the Open Science Framework (https://osf.io/8fsx7).

Patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA) are considered to have a symptomatic venous thromboembolism (VTE) risk of 1.0%–1.5% despite thromboprophylaxis. Fast-track treatment protocols have substantially lowered the VTE risk in most patients. Hence, the majority of patients may be unnecessarily exposed to the burden and risk of thromboprophylaxis. On the contrary, there are still patients with a high VTE risk who develop VTE despite thromboprophylaxis. Thus, tailored thromboprophylaxis treatment may potentially reduce both VTE and bleeding risk.

The DISTINCT (inDividual, targeted thrombosIS prophylaxis versus the standard ‘one-size-fits-all’ approach in patients undergoing Total hIp or total kNee replaCemenT) trial is a national, multicentre, randomised, multiarm, open-label trial. The main objective is to study whether tailored thromboprophylaxis reduces the occurrence of symptomatic VTE (primary outcome) and major bleeding (primary safety outcome) within 90 days after THA/TKA in comparison with standard thromboprophylaxis. Patients with a low, intermediate or high predicted VTE risk (based on the Thrombosis Risk Prediction following total hip and knee arthroplasty score (TRiP(plasty) score)) will be included in the DISTINCT-1, DISTINCT-2 or DISTINCT-3 studies, respectively. In the DISTINCT-1 trial, 3478 patients will be randomly allocated to receive either in-hospital thromboprophylaxis or standard prophylaxis. In the DISTINCT-2 cohort study, 2500 patients will receive standard prophylaxis. In the DISTINCT-3 trial, 4100 patients will be randomly allocated to receive either 6 weeks of high-dose thromboprophylaxis or standard prophylaxis. Standard prophylaxis consists of a low dose of any approved thromboprophylactic agent for 4 weeks. We hypothesise that (1) the efficacy of in-hospital only thromboprophylaxis is non-inferior in preventing VTE and equally safe compared with standard prophylaxis in patients with a low VTE risk (DISTINCT-1) and (2) prolonged high-dose thromboprophylaxis is superior in preventing VTE as compared with standard prophylaxis in patients with a high VTE risk (DISTINCT-3). Patients with intermediate VTE risk will be observed to evaluate VTE and bleeding rates (DISTINCT-2).

The protocol has been approved by the Medical Research Ethics Committee Leiden-Den Haag-Delft, EU-trial-number 2023-510186-98. Study results will be disseminated through peer-reviewed journals and during international conferences.

NCT06581965.