title: Sample size determinations for group-based randomized clinical trials with different levels of data hierarchy between experimental and control arms.
abstract: We derived sample size formulae for detecting main effects in group-based randomized clinical trials with different levels of data hierarchy between experimental and control arms. Such designs are necessary when experimental interventions need to be administered to groups of subjects whereas control conditions need to be administered to individual subjects. This type of trial, often referred to as a partially nested or partially clustered design, has been implemented for management of chronic diseases such as diabetes and is beginning to emerge more commonly in wider clinical settings. Depending on the research setting, the level of hierarchy of data structure for the experimental arm can be three or two, whereas that for the control arm is two or one. Such different levels of data hierarchy assume correlation structures of outcomes that are different between arms, regardless of whether research settings require two or three level data structure for the experimental arm. Therefore, the different correlations should be taken into account for statistical modeling and for sample size determinations. To this end, we considered mixed-effects linear models with different correlation structures between experimental and control arms to theoretically derive and empirically validate the sample size formulae with simulation studies.
authors.affiliation: 1 Department of Epidemiology and Population Health, Albert Einstein College of Medicine, NY, USA.
authors.forename: Moonseong
authors.initials: M
authors.lastname: Heo
authors.affiliation: 2 Department of Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, NY, USA.|3 Department of Psychiatry and Behavioral Sciences, Montefiore Medical Center, Albert Einstein College of Medicine, NY, USA.
authors.forename: Alain H
authors.initials: AH
authors.lastname: Litwin
authors.affiliation: 2 Department of Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, NY, USA.
authors.forename: Oni
authors.initials: O
authors.lastname: Blackstock
authors.affiliation: 4 Department of Radiology, Albert Einstein College of Medicine, NY, USA.
authors.forename: Namhee
authors.initials: N
authors.lastname: Kim
authors.affiliation: 1 Department of Epidemiology and Population Health, Albert Einstein College of Medicine, NY, USA.|2 Department of Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, NY, USA.|3 Department of Psychiatry and Behavioral Sciences, Montefiore Medical Center, Albert Einstein College of Medicine, NY, USA.
authors.forename: Julia H
authors.initials: JH
authors.lastname: Arnsten
mesh_terms: D006801:Humans; D016014:Linear Models; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D015203:Reproducibility of Results; D018401:Sample Size
keywords: group-based intervention; mixed-effects model; multi-level data; sample size; varying sizes