Comparing methods to estimate treatment effects on a continuous outcome in multicentre randomized controlled trials: A simulation study

Table 3 Estimates of intervention effects in COMPETE II trial

Model	Estimate of intervention effect	SE	95% CI	Variance component
A: Simple linear regression	1.270	0.246	(0.787, 1.753)	$σ_{e}^{2} = 7.712$
B: Fixed-effects regression	1.291	0.231	(0.836, 1.745)	$σ_{e}^{2} = 6.682$
C: Mixed-effects regression	1.263	0.230	(0.811, 1.714)	$σ_{e}^{2} = 6.678$ $σ_{b}^{2} = 1.069$
D: GEE	1.263	0.193	(0.884, 1.641)
E - 1: centre-level Fixed-effects model	1.397	0.219	(0.967, 1.826)
E - 2: centre-level Random-effects model	1.397	0.219	(0.967, 1.826)

SE: standard error; CI: confidence interval; $σ_{e}^{2}$ : within-centre variance; $σ_{b}^{2}$ : between-centre variance; ICC: intraclass (intracentre) correlation

ISSN: 1471-2288