title: Estimating statistical power for open-enrollment group treatment trials.
abstract: Modeling turnover in group membership has been identified as a key barrier contributing to a disconnect between the manner in which behavioral treatment is conducted (open-enrollment groups) and the designs of substance abuse treatment trials (closed-enrollment groups, individual therapy). Latent class pattern mixture models (LCPMMs) are emerging tools for modeling data from open-enrollment groups with membership turnover in recently proposed treatment trials. The current article illustrates an approach to conducting power analyses for open-enrollment designs based on the Monte Carlo simulation of LCPMM models using parameters derived from published data from a randomized controlled trial comparing Seeking Safety to a Community Care condition for women presenting with comorbid posttraumatic stress disorder and substance use disorders. The example addresses discrepancies between the analysis framework assumed in power analyses of many recently proposed open-enrollment trials and the proposed use of LCPMM for data analysis.
authors.affiliation: L.L. Thurstone Psychometric Laboratory, Department of Psychology, University of North Carolina, Chapel Hill, NC 27599, USA. aaml@email.unc.edu
authors.forename: Antonio A
authors.initials: AA
authors.lastname: Morgan-Lopez
authors.forename: Lissette M
authors.initials: LM
authors.lastname: Saavedra
authors.forename: Denise A
authors.initials: DA
authors.lastname: Hien
authors.forename: William
authors.initials: W
authors.lastname: Fals-Stewart
mesh_terms: D000704:Analysis of Variance; D001521:Behavior Therapy; D015897:Comorbidity; D003627:Data Interpretation, Statistical; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D015233:Models, Statistical; D009010:Monte Carlo Method; D011615:Psychotherapy, Group; D016032:Randomized Controlled Trials as Topic; D012107:Research Design; D018401:Sample Size; D012984:Software; D013313:Stress Disorders, Post-Traumatic / Q000453:epidemiology / Q000628:therapy*; D019966:Substance-Related Disorders / Q000453:epidemiology / Q000628:therapy*