title: Ignoring the group in group-level HIV/AIDS intervention trials: a review of reported design and analytic methods.
abstract: OBJECTIVE
  Studies evaluating the efficacy of HIV/AIDS interventions often involve the random assignment of groups of participants or the treatment of participants in groups. These studies require analytic methods that take within-group correlation into account. We reviewed published studies to determine the extent to which within-group correlation was dealt with properly.
  
  
  METHODS
  We reviewed group-randomized trials (GRTs) and individually randomized group treatment (IRGT) trials published in HIV/AIDS and general public health journals 2005-2009.
  
  
  METHODS
  At least two of the authors reviewed each article, recording descriptive characteristics, sample size estimation methods, analytic methods, and judgments about whether the methods took intraclass correlation into account properly.
  
  
  RESULTS
  Of those articles including sufficient information to judge whether analytic methods were correct, only 24% used only appropriate methods for dealing with the intraclass correlation. The percentages differed substantially for GRTs (41.7%) and IRGT trials (8.0%). Most of the articles (69.2%) also made no mention of a priori sample size estimation.
  
  
  CONCLUSIONS
  A majority of the articles in our review reported analyses ignoring the intraclass correlation. This practice may result in underestimated variance, inappropriately small P values, and incorrect conclusions about the effectiveness of interventions. Previous trials that were analyzed incorrectly need to be re-analyzed, and future trials should be designed and analyzed with appropriate methods. Also, journal reviewers and editors need to be aware of the special requirements for design and analysis of GRTs and IRGT trials and judge the quality of articles reporting on such trials according to appropriate standards.
authors.affiliation: Division of HIV/AIDS Prevention, National Center for HIV, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. sfv3@cdc.gov
authors.forename: Sherri L
authors.initials: SL
authors.lastname: Pals
authors.forename: Ryan E
authors.initials: RE
authors.lastname: Wiegand
authors.forename: David M
authors.initials: DM
authors.lastname: Murray
mesh_terms: D003627:Data Interpretation, Statistical; D005260:Female; D015658:HIV Infections / Q000453:epidemiology*; D006801:Humans; D008297:Male; D016032:Randomized Controlled Trials as Topic; D012107:Research Design / Q000706:statistics & numerical data*; D018401:Sample Size