title: Health related virtual communities and electronic support groups: systematic review of the effects of online peer to peer interactions.
abstract: OBJECTIVE
  To compile and evaluate the evidence on the effects on health and social outcomes of computer based peer to peer communities and electronic self support groups, used by people to discuss health related issues remotely.
  
  
  METHODS
  Analysis of studies identified from Medline, Embase, CINAHL, PsycINFO, Evidence Based Medicine Reviews, Electronics and Communications Abstracts, Computer and Information Systems Abstracts, ERIC, LISA, ProQuest Digital Dissertations, Web of Science.
  
  
  METHODS
  We searched for before and after studies, interrupted time series, cohort studies, or studies with control groups; evaluating health or social outcomes of virtual peer to peer communities, either as stand alone interventions or in the context of more complex systems with peer to peer components.
  
  
  METHODS
  Peer to peer interventions and co-interventions studied, general characteristics of studies, outcome measures used, and study results.
  
  
  RESULTS
  45 publications describing 38 distinct studies met our inclusion criteria: 20 randomised trials, three meta-analyses of n of 1 trials, three non-randomised controlled trials, one cohort study, and 11 before and after studies. Only six of these evaluated "pure" peer to peer communities, and one had a factorial design with a "peer to peer only" arm, whereas 31 studies evaluated complex interventions, which often included psychoeducational programmes or one to one communication with healthcare professionals, making it impossible to attribute intervention effects to the peer to peer community component. The outcomes measured most often were depression and social support measures; most studies did not show an effect. We found no evidence to support concerns over virtual communities harming people.
  
  
  CONCLUSIONS
  No robust evidence exists of consumer led peer to peer communities, partly because most peer to peer communities have been evaluated only in conjunction with more complex interventions or involvement with health professionals. Given the abundance of unmoderated peer to peer groups on the internet, research is required to evaluate under which conditions and for whom electronic support groups are effective and how effectiveness in delivering social support electronically can be maximised.
authors.affiliation: Department of Health Policy, Management and Evaluation, University of Toronto, Centre for Global eHealth Innovation, University Health Network, Toronto General Hospital, Toronto, ON, Canada M5G 2C4. geysenba@uhnres.utoronto.ca
authors.forename: Gunther
authors.initials: G
authors.lastname: Eysenbach
authors.forename: John
authors.initials: J
authors.lastname: Powell
authors.forename: Marina
authors.initials: M
authors.lastname: Englesakis
authors.forename: Carlos
authors.initials: C
authors.lastname: Rizo
authors.forename: Anita
authors.initials: A
authors.lastname: Stern
mesh_terms: D002986:Clinical Trials as Topic; D015331:Cohort Studies; D003695:Delivery of Health Care / Q000592:standards*; D015438:Health Behavior; D006266:Health Education / Q000379:methods; D006801:Humans; D020407:Internet; D007398:Interpersonal Relations; D017063:Outcome Assessment, Health Care; D010358:Patient Participation; D010379:Peer Group; D015397:Program Evaluation; D016032:Randomized Controlled Trials as Topic; D012657:Self-Help Groups / Q000458:organization & administration*; D012944:Social Support