TY  - JOUR
A1  - Gärtner, Thomas
A1  - Schneider, Juliana
A1  - Arnrich, Bert
A1  - Konigorski, Stefan
T1  - Comparison of Bayesian Networks, G-estimation and linear models to estimate causal treatment effects in aggregated N-of-1 trials with carry-over effects
T2  - BMC Medical Research Methodology
N2  - Background
The aggregation of a series of N-of-1 trials presents an innovative and efficient study design, as an alternative to traditional randomized clinical trials. Challenges for the statistical analysis arise when there is carry-over or complex dependencies of the treatment effect of interest.

Methods
In this study, we evaluate and compare methods for the analysis of aggregated N-of-1 trials in different scenarios with carry-over and complex dependencies of treatment effects on covariates. For this, we simulate data of a series of N-of-1 trials for Chronic Nonspecific Low Back Pain based on assumed causal relationships parameterized by directed acyclic graphs. In addition to existing statistical methods such as regression models, Bayesian Networks, and G-estimation, we introduce a carry-over adjusted parametric model (COAPM).

Results
The results show that all evaluated existing models have a good performance when there is no carry-over and no treatment dependence. When there is carry-over, COAPM yields unbiased and more efficient estimates while all other methods show some bias in the estimation. When there is known treatment dependence, all approaches that are capable to model it yield unbiased estimates. Finally, the efficiency of all methods decreases slightly when there are missing values, and the bias in the estimates can also increase.

Conclusions
This study presents a systematic evaluation of existing and novel approaches for the statistical analysis of a series of N-of-1 trials. We derive practical recommendations which methods may be best in which scenarios.
KW  - N-of-1 trials
KW  - Randomized clinical trials
KW  - Bayesian Networks;
KW  - G-estimation
KW  - Linear model
KW  - Simulation study
KW  - Chronic Nonspecific Low
KW  - Back Pain
Y1  - 2023
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/64303
SN  - 1471-2288
VL  - 23
IS  - 1
PB  - BMC
CY  - London
ER  -