title: The influence of social networking sites on health behavior change: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Our aim was to evaluate the use and effectiveness of interventions using social networking sites (SNSs) to change health behaviors.
  
  
  METHODS
  Five databases were scanned using a predefined search strategy. Studies were included if they focused on patients/consumers, involved an SNS intervention, had an outcome related to health behavior change, and were prospective. Studies were screened by independent investigators, and assessed using Cochrane's 'risk of bias' tool. Randomized controlled trials were pooled in a meta-analysis.
  
  
  RESULTS
  The database search retrieved 4656 citations; 12 studies (7411 participants) met the inclusion criteria. Facebook was the most utilized SNS, followed by health-specific SNSs, and Twitter. Eight randomized controlled trials were combined in a meta-analysis. A positive effect of SNS interventions on health behavior outcomes was found (Hedges' g 0.24; 95% CI 0.04 to 0.43). There was considerable heterogeneity (I(2) = 84.0%; T(2) = 0.058) and no evidence of publication bias.
  
  
  CONCLUSIONS
  To the best of our knowledge, this is the first meta-analysis evaluating the effectiveness of SNS interventions in changing health-related behaviors. Most studies evaluated multi-component interventions, posing problems in isolating the specific effect of the SNS. Health behavior change theories were seldom mentioned in the included articles, but two particularly innovative studies used 'network alteration', showing a positive effect. Overall, SNS interventions appeared to be effective in promoting changes in health-related behaviors, and further research regarding the application of these promising tools is warranted.
  
  
  CONCLUSIONS
  Our study showed a positive effect of SNS interventions on health behavior-related outcomes, but there was considerable heterogeneity. Protocol registration The protocol for this systematic review is registered at http://www.crd.york.ac.uk/PROSPERO with the number CRD42013004140.
authors.affiliation: Portuguese School of Public Health, Universidade Nova de Lisboa, Lisbon, Portugal.
authors.forename: Liliana
authors.initials: L
authors.lastname: Laranjo
authors.affiliation: Centre for Health Informatics, Australian Institute of Health Innovation, University of New South Wales, Sydney, Australia.
authors.forename: Amaël
authors.initials: A
authors.lastname: Arguel
authors.affiliation: Family Medicine Unit, Department of Social Sciences and Health, Faculty of Medicine, University of Porto, Porto, Portugal.
authors.forename: Ana L
authors.initials: AL
authors.lastname: Neves
authors.affiliation: UNSW Medicine, University of New South Wales, Sydney, Australia.
authors.forename: Aideen M
authors.initials: AM
authors.lastname: Gallagher
authors.affiliation: Royal Hospital for Women, Sydney, Australia.
authors.forename: Ruth
authors.initials: R
authors.lastname: Kaplan
authors.affiliation: UNSW Medicine, University of New South Wales, Sydney, Australia.
authors.forename: Nathan
authors.initials: N
authors.lastname: Mortimer
authors.affiliation: ACES Estuário do Tejo, Lisbon, Portugal.
authors.forename: Guilherme A
authors.initials: GA
authors.lastname: Mendes
authors.affiliation: Centre for Health Informatics, Australian Institute of Health Innovation, University of New South Wales, Sydney, Australia.
authors.forename: Annie Y S
authors.initials: AY
authors.lastname: Lau
mesh_terms: D054626:Consumer Health Information; D015438:Health Behavior; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D061108:Social Media; D060756:Social Networking
keywords: Behavior Change; Consumer Health; Social Media; Social Network; Social Networking Site