title: A systematic review on the clustering and co-occurrence of multiple risk behaviours.
abstract: Risk behaviours, such as smoking and physical inactivity account for up to two-thirds of all cardiovascular deaths, and are associated with substantial increased mortality in many conditions including cancer and diabetes. As risk behaviours are thought to co-occur in individuals we conducted a systematic review of studies addressing clustering or co-occurrence of risk behaviours and their predictors. As the main aim of the review was to inform public health policy in England we limited inclusion to studies conducted in the UK.
  
  
  
  Key databases were searched from 1990 to 2016. We included UK based cross-sectional and longitudinal studies that investigated risk behaviours such as smoking, physical inactivity, unhealthy diet. High heterogeneity precluded meta-analyses.
  
  
  
  Thirty-seven studies were included in the review (32 cross-sectional and five longitudinal). Most studies investigated unhealthy diet, physical inactivity, alcohol misuse, and smoking. In general adult populations, there was relatively strong evidence of clustering between alcohol misuse and smoking; and unhealthy diet and smoking. For young adults, there was evidence of clustering between sexual risk behaviour and smoking, sexual risk behaviour and illicit drug use, and sexual risk behaviour and alcohol misuse. The strongest associations with co-occurrence and clustering of multiple risk behaviours were occupation (up to 4-fold increased odds in lower SES groups) and education (up to 5-fold increased odds in those with no qualifications).
  
  
  
  Among general adult populations, alcohol misuse and smoking was the most commonly identified risk behaviour cluster. Among young adults, there was consistent evidence of clustering found between sexual risk behaviour and substance misuse. Socio-economic status was the strongest predictor of engaging in multiple risk behaviours. This suggests the potential for interventions targeting multiple risk behaviours either sequentially or concurrently particularly where there is evidence of clustering. In addition, there is potential for intervening at the social or environmental level due to the strong association with socio-economic status.
authors.affiliation: Centre for Reviews and Dissemination, University of York, York, YO10 5DD, UK.
authors.forename: Nick
authors.initials: N
authors.lastname: Meader
authors.affiliation: Centre for Reviews and Dissemination, University of York, York, YO10 5DD, UK.
authors.forename: Kristelle
authors.initials: K
authors.lastname: King
authors.affiliation: Centre for Reviews and Dissemination, University of York, York, YO10 5DD, UK.
authors.forename: Thirimon
authors.initials: T
authors.lastname: Moe-Byrne
authors.affiliation: Centre for Reviews and Dissemination, University of York, York, YO10 5DD, UK.
authors.forename: Kath
authors.initials: K
authors.lastname: Wright
authors.affiliation: Department of Health Sciences, University of York, York, UK.
authors.forename: Hilary
authors.initials: H
authors.lastname: Graham
authors.affiliation: Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Petticrew
authors.affiliation: Population, Policy and Practice, UCL Institute of Child Health, London, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Power
authors.affiliation: UKCRC Centre for Diet and Activity Research (CEDAR), MRC Epidemiology Unit, University of Cambridge, Cambridge, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: White
authors.affiliation: Centre for Reviews and Dissemination, University of York, York, YO10 5DD, UK. amanda.sowden@york.ac.uk.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Sowden
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D005260:Female; D015438:Health Behavior; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011634:Public Health; D012309:Risk-Taking; D012959:Socioeconomic Factors; D006113:United Kingdom; D055815:Young Adult
keywords: Clustering; Co-occurrence; Multiple risk behaviours; Systematic review