mixedtrial

Mixedtrial is a term used in research methodology to describe a study design that combines multiple trial methodologies within a single project. In a mixed trial, elements of randomized controlled trials (RCTs) may be integrated with observational or real-world components, or multiple data-generating strategies are used. The aim is to balance internal validity with external validity and to improve efficiency by leveraging information from different sources.

Design and methods. A mixed trial may include an RCT arm alongside a registry-based or cohort arm; assignment might be partly randomized, partly allocation based on clinical considerations; data may come from standardized measurements, patient registries, and routine electronic health records. Analysis often employs causal inference methods to adjust for confounding, along with pre-specified adaptive rules or interim analyses. Classifications include hybrid randomized-pragmatic designs, randomized-with-registry designs, and multi-arm, multi-stage mixed designs.

Applications and examples. Mixed trials are used in clinical research to evaluate efficacy under controlled conditions while assessing real-world effectiveness. They also appear in education, psychology, and digital health, where laboratory experiments can be complemented by field data. For instance, a mixed trial for a new antihypertensive might compare outcomes in a strict RCT while simultaneously tracking safety and adherence in routine practice via a registry.

Advantages and challenges. Benefits include enhanced external validity, more efficient use of data, and faster decision-making. Challenges involve methodological complexity, potential bias if non-randomized elements are not properly controlled, regulatory considerations, and the need for rigorous statistical analysis plans.

See also: mixed-methods research, pragmatic trials, adaptive trial designs, hybrid designs.