title: Persistent spatial clusters of high body mass index in a Swiss urban population as revealed by the 5-year GeoCoLaus longitudinal study.
abstract: OBJECTIVE
  Body mass index (BMI) may cluster in space among adults and be spatially dependent. Whether and how BMI clusters evolve over time in a population is currently unknown. We aimed to determine the spatial dependence of BMI and its 5-year evolution in a Swiss general adult urban population, taking into account the neighbourhood-level and individual-level characteristics.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  Swiss general urban population.
  
  
  METHODS
  6481 georeferenced individuals from the CoLaus cohort at baseline (age range 35-74 years, period=2003-2006) and 4460 at follow-up (period=2009-2012).
  
  
  METHODS
  Body weight and height were measured by trained healthcare professionals with participants standing without shoes in light indoor clothing. BMI was calculated as weight (kg) divided by height squared (m(2)). Participants were geocoded using their postal address (geographic coordinates of the place of residence). Getis-Ord Gi statistic was used to measure the spatial dependence of BMI values at baseline and its evolution at follow-up.
  
  
  RESULTS
  BMI was not randomly distributed across the city. At baseline and at follow-up, significant clusters of high versus low BMIs were identified and remained stable during the two periods. These clusters were meaningfully attenuated after adjustment for neighbourhood-level income but not individual-level characteristics. Similar results were observed among participants who showed a significant weight gain.
  
  
  CONCLUSIONS
  To the best of our knowledge, this is the first study to report longitudinal changes in BMI clusters in adults from a general population. Spatial clusters of high BMI persisted over a 5-year period and were mainly influenced by neighbourhood-level income.
authors.affiliation: Laboratory of Geographic Information Systems (LASIG), School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland MicroGIS Foundation for Spatial Analysis (MFSA), Saint-Sulpice, Switzerland Group of Geographic Information Research and Analysis in Public Health (GIRAPH).
authors.forename: Stéphane
authors.identifier: http://orcid.org/0000-0002-1184-7501
authors.initials: S
authors.lastname: Joost
authors.affiliation: Laboratory of Geographic Information Systems (LASIG), School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
authors.forename: Solange
authors.identifier: http://orcid.org/0000-0002-1235-6747
authors.initials: S
authors.lastname: Duruz
authors.affiliation: Department of Internal Medicine, Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Pedro
authors.initials: P
authors.lastname: Marques-Vidal
authors.affiliation: Division of Chronic Diseases, Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Murielle
authors.initials: M
authors.lastname: Bochud
authors.affiliation: Division of Chronic Diseases, Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Silvia
authors.initials: S
authors.lastname: Stringhini
authors.affiliation: Division of Chronic Diseases, Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Fred
authors.initials: F
authors.lastname: Paccaud
authors.affiliation: Faculty of Medicine, Unit of Population Epidemiology, Division of Primary Care Medicine, Department of Community Medicine, Primary Care and Emergency Medicine, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Gaspoz
authors.affiliation: Faculty of Medicine, Unit of Population Epidemiology, Division of Primary Care Medicine, Department of Community Medicine, Primary Care and Emergency Medicine, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Theler
authors.affiliation: MicroGIS Foundation for Spatial Analysis (MFSA), Saint-Sulpice, Switzerland Group of Geographic Information Research and Analysis in Public Health (GIRAPH).
authors.forename: Joël
authors.initials: J
authors.lastname: Chételat
authors.affiliation: Department of Internal Medicine, Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Gérard
authors.initials: G
authors.lastname: Waeber
authors.affiliation: Department of Internal Medicine, Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Vollenweider
authors.affiliation: Group of Geographic Information Research and Analysis in Public Health (GIRAPH) Department of Internal Medicine, Lausanne University Hospital (CHUV), Lausanne, Switzerland Division of Chronic Diseases, Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital (CHUV), Lausanne, Switzerland Faculty of Medicine, Unit of Population Epidemiology, Division of Primary Care Medicine, Department of Community Medicine, Primary Care and Emergency Medicine, Geneva University Hospitals and University of Geneva, Geneva, Switzerland Department of Epidemiology, Emory University, Atlanta, Georgia, USA.
authors.forename: Idris
authors.initials: I
authors.lastname: Guessous
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology*; D012111:Residence Characteristics / Q000706:statistics & numerical data; D012959:Socioeconomic Factors; D013557:Switzerland / Q000453:epidemiology; D014504:Urban Health / Q000706:statistics & numerical data; D015430:Weight Gain
keywords: EPIDEMIOLOGY; NUTRITION & DIETETICS; PUBLIC HEALTH