Statistics

Clinical trial

Family medicine

Clinical study design

Political science

Randomization

Research design

Mathematics

Meta-analysis

Internal medicine

Blinding

Medicine

Nursing

Psychological intervention

MEDLINE

Journal of Clinical Epidemiology

Objectives To summarize the methods of design, analysis, and meta-analysis used in N-of-1 trials. Study Design and Setting Electronic search for English language articles published from 1950 to 2013. N-of-1 trials were selected if they followed an ABAB design and if they assessed a health intervention for a medical condition. Elements of design, analysis, and meta-analysis were extracted. Results We included 100 reports representing 1,995 participants. N-of-1 trials have been conducted in over 50 health conditions. Most reports incorporated the use of elements that maintain methodological rigor, including randomization, blinding, and formal outcome assessment; however, many failed to address trial registration, funding source, and adverse events. Most reports statistically analyzed individual N-of-1 trials; however, only a small proportion of included series meta-analyzed their results. Conclusions N-of-1 trials have the ability to assess treatment response in individual participants and can be used for a var...

N-of-1 trials are a tapestry of heterogeneity