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Body mass index trajectories among the Canadian workforce and their association with work environment trajectories over 17 years
  1. Kathleen G Dobson1,2,
  2. Mahée Gilbert-Ouimet3,4,
  3. Cameron Mustard1,2,
  4. Peter M Smith1,2,5
  1. 1 Institute for Work & Health, Toronto, Ontario, Canada
  2. 2 Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
  3. 3 Department of Health Sciences, Université du Québec à Rimouski, Campus de Lévis, Lévis, Québec, Canada
  4. 4 Population Health and Optimal Health Practices Unit, Centre de recherche du CHU de Québec-Université Laval, Hôpital du Saint-Sacrement, Québec, Québec, Canada
  5. 5 Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
  1. Correspondence to Kathleen G Dobson, Institute for Work & Health, Toronto, Ontario, Canada; kathleen.dobson{at}


Objective To determine the number of latent body mass index (BMI) trajectories from 1994 to 2010 among working Canadians and their association with concurrent trajectories in work environment exposures.

Methods Data of employed individuals from the longitudinal Canadian National Population Health Survey were used. Group-based trajectory modelling was used to determine the number of latent BMI trajectories and concurrent psychosocial work environment trajectories. A multinomial logistic regression of BMI trajectory membership on trajectories in work environment dimensions (skill discretion, decision latitude, psychological demands, job insecurity, social support, physical exertion) was then explored.

Results Four latent BMI trajectories corresponding to normal, overweight, obese and very obese BMI values were found. Each trajectory saw an increase in BMI (~2–4 kg/m2) over the 17-year period. A higher decision authority trajectory was associated with lower odds of belonging to the overweight and obese trajectories when compared with the normal weight trajectory. A decreasing physical exertion trajectory was associated with higher odds of belonging to the very obese trajectory when compared with the normal weight trajectory.

Conclusions Four BMI trajectories are present in the Canadian workforce; all trajectories saw increased body weight over time. Declining physical exertion and lower decision authority in the work environment over time is associated with increased likelihood of being in overweight and obese trajectories.

  • epidemiology
  • public health
  • longitudinal studies

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  • Contributors KD, MG-O, PMS and CM conceived the research question, study design, and revised and approved this manuscript. KD analysed the data and drafted the initial manuscript. All authors participated in approving the final version to be published and agreeing to be accountable for all aspects of the work by ensuring that questions related to the accuracy or integrity of any part of the work were appropriately investigated and resolved.

  • Funding This work was supported by a project grant from the Canadian Institutes for Health Research (CIHR) (grant no. 310898). PMS is supported through a Research Chair in Gender, Work and Health from CIHR. KD is supported through a doctoral scholarship through CIHR. MG-O is supported through a CIHR postdoctoral fellowship. Access to the data for this paper was enabled through Statistics Canada’s Research Data Centre at the University of Toronto.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval This study was approved by the University of Toronto.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement The data for this study were accessed through the Canadian Research Data Centre Network.