Application of multiple-group latent growth model to determine the effect of shift work on body mass index among petrochemical industries staff

Background: Shift work can be defined as work activity scheduled in which employees work outside standard daytime hours. Some reports have shown that shift work is associated with several health problems. The main objective of this research was to explore the effect of shift work on body mass index (BMI) over time among Iranian petroleum industry staff. Methods: This longitudinal study sample was consisted of 3,686 (1,872 day workers and 1,814 shift workers) petrochemical industries staff in Mahshahr, southwest of Iran, from 2012 to 2015. The weight and height of these staff were measured using standard techniques and equipment. Multiple-group latent growth curve modeling was used to determine the effect of shift working on BMI trajectories over this period of time via Mplus software, version 6.0. Results: The mean (±SD) age of the shift workers and day workers were 38.96 (±8.36) and 43.33 (±8.35) years, respectively. Findings from the modeling approach showed that the slope of BMI in shift workers on average was 0.14 kg/m2 greater than the day workers in years under study (p<0.001). Conclusion: The findings of the current study suggest that shift work can be considered as a potential risk indicator for higher weight gain in petrochemical staff. Hence, health policy-makers should organize health screening programs and periodical checkups to find high-risk staff and control unhealthy lifestyle factors in these industries.