title: Sequential allocation to balance prognostic factors in a psychiatric clinical trial.
abstract: OBJECTIVE
  This paper aims to describe and discuss a minimization procedure specifically designed for a clinical trial that evaluates treatment efficacy for OCD patients.
  
  
  METHODS
  Aitchison's compositional distance was used to calculate vectors for each possibility of allocation in a covariate adaptive method. Two different procedures were designed to allocate patients in small blocks or sequentially one-by-one.
  
  
  RESULTS
  We present partial results of this allocation procedure as well as simulated data. In the clinical trial for which this procedure was developed, successful balancing between treatment arms was achieved. Separately, in an exploratory analysis, we found that if the arrival order of patients was altered, most patients were allocated to a different treatment arm than their original assignment.
  
  
  CONCLUSIONS
  Our results show that the random arrival order of patients determine different assignments and therefore maintains the unpredictability of the allocation method. We conclude that our proposed procedure allows for the use of a large number of prognostic factors in a given allocation decision. Our method seems adequate for the design of the psychiatric trials used as models. Trial registrations are available at clinicaltrials.gov NCT00466609 and NCT00680602.
authors: Faculdade de Medicina, Institute of Psychiatry, Hospital das Clínicas, Universidade de São Paulo, São Paulo, Brazil. victor.ime@gmail.com
authors: Victor
authors: V
authors: Fossaluza
authors: Juliana Belo
authors: JB
authors: Diniz
authors: Basilio de Bragança
authors: Bde B
authors: Pereira
authors: Eurípedes Constantino
authors: EC
authors: Miguel
authors: Carlos Alberto de Bragança
authors: CA
authors: Pereira
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder / Q000628:therapy*; D018579:Patient Selection; D011379:Prognosis; D018401:Sample Size