Preoperative administration of tranexamic acid (TXA) reduces perioperative blood loss and transfusion requirements in total hip arthroplasty (THA), but optimal dosing remains uncertain due to the narrow range of doses explored in prior studies. This study aims to define the dose–response of intravenous TXA in THA, focusing on perioperative haemoglobin drop to improve blood-sparing effect.

This monocentric, double-blind, placebo-controlled, parallel-group, dose-finding study will enrol 170 adults undergoing THA, aiming to randomise 150 patients. Participants will be allocated using a minimisation technique with a random component in equal proportions to receive either placebo or one of four intravenous TXA doses: 300 mg, 500 mg, 1000 mg or 3000 mg. Dose selection and sample size are based on a model-based meta-analysis that employed a maximum effect (Emax) model with a maximum effect of 40% and an ED50 (dose providing 50% of Emax) of 400 mg. The primary outcome will be the relative perioperative haemoglobin drop at postoperative day 3. Secondary outcomes include TXA exposure and perioperative fibrinolytic activity as measured by D-dimer levels. Only patients receiving the allocated study treatment will be analysed (modified intention-to-treat population). The dose–response relationship for the primary outcome will be analysed using non-linear mixed-effect models.

The study protocol was approved by the French ethics committee (Institutional Review Board Sud Méditerranée V) and the French National Agency for the Safety of Medicines and Health Products (ANSM). Results will be disseminated at conferences and published in peer-reviewed journals.

CTIS 2022-502532-38-01; NCT03822793.

Alcohol consumption that damages health remains highly prevalent in Sweden despite macrolevel intervention measures such as availability, restrictions and taxation. As understanding of behaviour change develops, there may be an opportunity to enhance individual level interventions by targeting personal dimensions of behaviour, such as underlying motives for drinking alcohol and readiness to change behaviour. This protocol describes a randomised controlled trial aimed at estimating the effectiveness of an intervention tailored to motives and readiness to change.

A three-arm, parallel groups, randomised controlled trial will be used to estimate the effects of a motives and readiness to change tailored intervention. We will use a Bayesian sequential design to decide when to stop recruitment, with target criteria for benefit, harm and futility. Recruitment will be completed via web adverts and social media. Inclusion criteria are being aged 18 or older, having access to a mobile phone and being classified as a risky drinker. Participants allocated to the two intervention groups will receive either a personalised digital intervention or an intervention with enhanced tailoring for motives and readiness to change. The personalised intervention consists of weekly screening, personalised feedback and tools for planning behaviour. The enhanced tailored version will follow the same logic but will contain materials tailored for individuals’ drinking motives and readiness to change. The control group will be redirected to two national websites with information about alcohol and health. Outcome measures are weekly alcohol consumption and monthly heavy drinking episodes, which will be contrasted with regression models and estimated using Bayesian inference.

Ethical approval was obtained from the Swedish Ethical Review Authority on 16 April 2024, (Dnr 2024-01630-01). The results of the study will be disseminated in academic journals and research conferences.

The trial was preregistered in the ISRCTN Registry on 12 June 2024 (ISRCTN87600318).