title: Do colleagues influence our lifestyle: the matter of smoking, body mass index and leisure-time physical activity?
abstract: OBJECTIVE
  Previous research has indicated that health behaviours tend to cluster in social networks, but few have studied the cluster effect in workgroups. We examined the effect of workgroups on current state and change in three indicators of health behaviours (smoking, body mass index (BMI) and physical activity). Further, we examined whether health behaviours of the respondents at group level predicted lifestyle changes.
  
  
  METHODS
  In a prospective cohort (n=4730), employees from 250 workgroups in the Danish eldercare sector answered questionnaires at baseline (2005) and follow-up (2006). Multilevel regression models were used to examine the effect of workgroups.
  
  
  RESULTS
  Workgroups accounted for 6.49% of the variation in smoking status, 6.56% of amount smoked and 2.62% of the variation in current BMI. We found no significant workgroup clustering in physical activity or lifestyle changes. Furthermore, changes in smoking status (cessation) and weight gain were seen in workgroups with high percentage of smokers and high levels of BMI.
  
  
  CONCLUSIONS
  We found modest evidence for clustering of some health behaviours within workgroups, which could be due to social learning or selection into and out of workgroups. Future health promotion programmes at worksites should recognize the potential clustering of lifestyle behaviours within workgroups.
authors: National Research Centre for the Working Environment (NRCWE), Lersoe Parkallé 105, 2100 Copenhagen, Denmark. Electronic address: hgq@nrcwe.dk.
authors: Helle Gram
authors: HG
authors: Quist
authors: Department of Public Health, Section of Social Medicine, Oester Farimagsgade 5, 1014 Copenhagen, Denmark. Electronic address: ulch@sund.ku.dk.
authors: Ulla
authors: U
authors: Christensen
authors: National Research Centre for the Working Environment (NRCWE), Lersoe Parkallé 105, 2100 Copenhagen, Denmark; Danish Working Environment Authority, Postboks 1228, 0900 Copenhagen C, Denmark. Electronic address: igc@at.dk.
authors: Isabella Gomes
authors: IG
authors: Carneiro
authors: National Research Centre for the Working Environment (NRCWE), Lersoe Parkallé 105, 2100 Copenhagen, Denmark. Electronic address: jvh@nrcwe.dk.
authors: Jørgen Vinsløv
authors: JV
authors: Hansen
authors: National Research Centre for the Working Environment (NRCWE), Lersoe Parkallé 105, 2100 Copenhagen, Denmark; Department of Public Health, Section of Social Medicine, Oester Farimagsgade 5, 1014 Copenhagen, Denmark; QualityMetric/OptumInsight, 24 Albion Road, Lincoln, RI 02865, USA. Electronic address: jbj@nrcwe.dk.
authors: Jakob Bue
authors: JB
authors: Bjorner
mesh_terms: D000328:Adult; D015992:Body Mass Index; D003718:Denmark; D015444:Exercise / Q000523:psychology*; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009765:Obesity; D010379:Peer Group; D011446:Prospective Studies; D012044:Regression Analysis; D012907:Smoking / Q000523:psychology*; D011795:Surveys and Questionnaires; D017132:Workplace
keywords: Cluster; Health care workers; Homophily; Lifestyle changes