Biomedical science and pharmaceutical research embrace n-of-1 trials

The use and scientific acceptance  of  “n-of-1” trials have accelerated in recent years, especially in connection with personalized medicine and drug discovery. This increase in interest and acceptance is reflected in the number of studies on the field.

A Google Scholar search (July 26, 2020) for “n-of-1 trial validity” for all date ranges, yielded 3,430 results. By contrast, the same search string for the period 2019-2020,  yielded 527 results. That search found 221 results in the first seven months of 2020.

Those studies reflect a broad acceptance with major studies comparing n-of-1 trials to to Randomized C0ntrol Studies and other long-accepted research methods [1,2,3,4,5]

In addition, established standards organizations such as SPIRIT [6] and CONSORT [7] have embraced n-of-1 trials and offer structures for reporting on most major forms of biomedical studies.

This article from the British Medical Journal [8] notes:

“Well conducted, randomised clinical trials create the evidence base that informs modern medical practice, guidelines, and regulatory decisions. However, these trials estimate average treatment effects, providing little information about heterogeneity and no information about individual treatment effects.

“Randomised clinical trials are not always feasible, are rarely conducted on rare diseases, and often exclude individuals with comorbid conditions or concurrent treatments even though these individuals constitute the majority of patients.

“Based on the methodology of randomised clinical trials, n-of-1 trials can rigorously measure intervention effects for individuals, either singly or in a series.”


[1] Single-case experimental design yielded an effect estimate corresponding to a randomized controlled trial

[2] Making the switch: From case studies to N – of – 1 trials

[3] Practice-Based Research in Complementary Medicine: Could N-of-1 Trials Become the New Gold Standard?

[4] Comparison of Aggregated N-of-1 Trials with Parallel and Crossover Randomized Controlled Trials Using Simulation Studies

[5] To meta-analyze or not to meta-analyze? A combined meta-analysis of N-of-1 trial data with RCT data

[6] SPIRIT – Standard Protocol Items: Recommendations for Interventional Trials

[7] CONSORT – Consolidated Standards of Reporting Trials

[8] SPIRIT extension and elaboration for n-of-1 trials: SPENT 2019 checklist

More references

N-of-1 Trials Take on Challenges in Health Care

Understanding and misunderstanding randomized controlled trials