What are N of 1 trials?
N of 1 trials are a type of personalised clinical trial, which are trials that apply a type of single case experimental design to understand how an individual responds to a treatment or intervention. Common types of single case designs are described below.
N of 1 Trial
Design
N of 1 trials are multi-cycle, double-blind, individualised randomised controlled trials. A patient undergoes treatment and comparator periods. There is typically 3 or more cycles of paired periods and randomisation is used (e.g. BAABAB). The patient is their own control. Outcomes are recorded using validated outcome measures. After analysing the data, a report is sent to the doctor and patient for discussion about whether the treatment works for them.
Multiple Baseline Design
In a multiple baseline design the start of treatment is staggered (started at different times) across individuals. This strengthens conclusions because changes observed in the outcome measured are likely due to the treatment implemented rather than to an external factor. By gathering data from many individuals , inferences can be made about the likelihood that the measured effect generalises to a larger population.
Single-Case Observational Design
Single-case observational designs (also referred to as N of 1 observational designs involve repeated measurement of an outcome (e.g., pain) in an individual over time, but without any intervention. The purpose of using a single-case observational designs is to draw conclusions about naturally-occurring patterns and outcome predictors. This information can provide insight into potentially effective intervention strategies.