# The N-of-1 Trials and where to use them in Rheumatology

## TL;DR

N-of-1 trials are personalized, randomized studies in rheumatology that help find the best treatment for each patient, improving outcomes and reducing costs.

## Contribution

This paper reviews the use of N-of-1 trials in rheumatology, highlighting their benefits for personalized medicine and clinical decision-making.

## Key findings

- N-of-1 trials improve treatment response, quality of life, and reduce adverse events in rheumatology.
- These trials support patient-centric care by tailoring outcomes to individual needs and comorbidities.
- They can reduce economic costs and aid in deprescribing unnecessary medications.

## Abstract

N-of-1 trials constitute single-patient, randomised, crossover and often, double-blind clinical trials, where each patient serves as his/her own control. The implementation of n-of-1 trials propels us towards the practice of patient-centric medicine, while exhibiting multiple additional advantages for rheumatology, including the identification of the most appropriate treatment for each patient, improved response, outcomes and quality of life, fewer adverse events, and reduced economic costs. The design employs similar aspects to randomised clinical trials in order to maintain scientific rigor, while producing clinically relevant treatment outcomes, tailored to each patient.

For the purpose of this review, we searched PubMed and clinicaltrials.gov for n-of-1 trials or series conducted on patients with rheumatic diseases until August 2024.

N-of-1 trials can facilitate clinical decisions and evaluate the efficacy of medications, lifestyle interventions, or adjuvant treatments (i.e. for pain), while focusing on disease-specific outcomes or comorbidities (cachexia, obesity, etc.). In this review, the advantages and limitations of n-of-1 trials in rheumatology are discussed and trials performed on patients with rheumatic diseases are presented.

Employing the n-of-1 design in everyday clinical practice consists of the epitome of patient-centred medicine, greatly benefiting patients and clinicians, facilitating deprescribing, and reducing the economic burden of pharmacotherapy.