title: Socioeconomic, temporal and regional variation in body mass index among 188,537 Swiss male conscripts born between 1986 and 1992.
abstract: BACKGROUND
  Rising levels of overweight and obesity are important public-health concerns worldwide. The purpose of this study is to elucidate their prevalence and trends in Switzerland by analyzing variations in Body Mass Index (BMI) of Swiss conscripts.
  
  
  METHODS
  The conscription records were provided by the Swiss Army. This study focussed on conscripts 18.5-20.5 years of age from the seven one-year birth cohorts spanning the period 1986-1992. BMI across professional status, area-based socioeconomic position (abSEP), urbanicity and regions was analyzed. Two piecewise quantile regression models with linear splines for three birth-cohort groups were used to examine the association of median BMI with explanatory variables and to determine the extent to which BMI has varied over time.
  
  
  RESULTS
  The study population consisted of 188,537 individuals. Median BMI was 22.51 kg/m2 (22.45-22.57 95% confidence interval (CI)). BMI was lower among conscripts of high professional status (-0.46 kg/m2; 95% CI: -0.50, -0.42, compared with low), living in areas of high abSEP (-0.11 kg/m2; 95% CI: -0.16, -0.07 compared to medium) and from urban communities (-0.07 kg/m2; 95% CI: -0.11, -0.03, compared with peri-urban). Comparing with Midland, median BMI was highest in the North-West (0.25 kg/m2; 95% CI: 0.19-0.30) and Central regions (0.11 kg/m2; 95% CI: 0.05-0.16) and lowest in the East (-0.19 kg/m2; 95% CI: -0.24, -0.14) and Lake Geneva regions (-0.15 kg/m2; 95% CI: -0.20, -0.09). Trajectories of regional BMI growth varied across birth cohorts, with median BMI remaining high in the Central and North-West regions, whereas stabilization and in some cases a decline were observed elsewhere.
  
  
  CONCLUSIONS
  BMI of Swiss conscripts is associated with individual and abSEP and urbanicity. Results show regional variation in the levels and temporal trajectories of BMI growth and signal their possible slowdown among recent birth cohorts.
authors.affiliation: Centre for Evolutionary Medicine, Institute of Anatomy, University of Zurich, Zurich, Switzerland; Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland.
authors.forename: Radoslaw
authors.initials: R
authors.lastname: Panczak
authors.affiliation: Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland.
authors.forename: Marcel
authors.initials: M
authors.lastname: Zwahlen
authors.affiliation: Department of Economics, University of Zurich, Zurich, Switzerland.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Woitek
authors.affiliation: Centre for Evolutionary Medicine, Institute of Anatomy, University of Zurich, Zurich, Switzerland.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Rühli
authors.affiliation: Centre for Evolutionary Medicine, Institute of Anatomy, University of Zurich, Zurich, Switzerland.
authors.forename: Kaspar
authors.initials: K
authors.lastname: Staub
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D006801:Humans; D008297:Male; D012959:Socioeconomic Factors; D013557:Switzerland; D055815:Young Adult