Iranian Journal of

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  Background and Objectives : Failure to gain weight (FTG) is one of the predominant health issues in children. The aim of this study is application of longitudinal transition model in determining the prognostic factors for failure to gain weight in children under two years.

  Methods: In this study, 363 children under 2 years that were visited at the health centers in the east of Tehran were studied. Samples were selected using the two stage clustering method. The study variables were measured repeatedly in 18 consecutive times. Since the data was longitudinal and are dependent, first order transition model was used to determine the risk factors of failure to gain weight. All analyses conducted in R.

  Results : The mean (±sd) birth weight was 3057gr(± 838) and 6.9% of the children weighed less than 2500gr at birth. Moreover, 231 children (63.6 %) had no FTW until 2 years of age while 23 ( 6.3 %) had three or more episodes of FTW. Diarrhea (P<0.001), weaning (P<0.001), catching cold (<0.001), and teething (P<.001) were significant risk factors of failure to gain weight. To measure the association between weight loss and the weight in the previous visit, the logarithm of odds ratios was used that was significant (P=0.039).

  Conclusion: The association between two consecutive measurements showed that any failure in weight would affect weight gain in the next period of time and the effect of weight deficiency remains for at least one month.

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Background and Objectives: Shift work could threaten health in the long term. The present research aimed to assess the association between shift work and body mass index (BMI) using the multilevel (hierarchical) model during a particular period of time.
Methods: The data of this longitudinal study were collected from a sample of Esfahan’s Mobarakeh steel and Polyacryl companies personnel during 2008 to 2011. Shift work schedule included day work and rotational shift work. The multilevel regression model was utilized for analysing the data and assessing the effect of shift work on BMI by controlling confounding variables including marital status, work expectation, age, company, and educational level.
Results: In this study, of 1368 workers, 42.3% (n=578) and 57.7% (n=790) were day workers and rotating shift workers, respectively. The mean (±SD) age of the day workers and rotating shift workers was 33.07 (±8.66) years and 33.31 (±8.70) years, respectively. After adjusting for confounding variables in a two-level hierarchical model, the association between shift work and BMI was not statistically significant (P=0.837). About 90% of total variation was related to personnel.
Conclusion: According to the results of the present study, no statistically significant relationship was found between shift work schedule and BMI. Thus, other similar studies with a longer follow up period (more than four years) and controlling more confounder factors are necessary to evaluate the relationship between shift work and BMI more accurately.