Application of n-of-1 treatment trials in schizophrenia: systematic review

BACKGROUND: Single patient or ‘n-of-1’ trials are a pragmatic method to achieve optimal, evidence-based treatments for individual patients. Such trials could be particularly valuable in chronic, heterogeneous, difficult to treat illnesses such as schizophrenia. AIMS: To identify how often, and in what way, n-of-1 trials have been used in schizophrenia. METHOD: We performed a systematic search in the major electronic databases for studies adopting n-of-1 methodology in schizophrenia, published in English from the start of records until the end of January 2017. RESULTS: We identified six studies meeting inclusion criteria. There was wide variability in study methodology and analysis. Each trial reported positive outcomes for their respective intervention, but all studies were at high risk of bias. CONCLUSIONS: In conclusion, n-of-1 trials are currently underutilised in schizophrenia. Existing trials suggest the method is well tolerated and potentially effective in achieving optimal treatments for patients, but more standardised methods of design, execution and analysis are required in future trials. DECLARATION OF INTEREST: S.M.L. has received grants and personal fees from Janssen, and personal fees from Otsuka and Sunovion, in the past 3 years, outside the submitted work.