Application of the Longitudinl Transition Model in Analzing Failure to Gain Weight in Children Under Two Years of Age

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. 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. 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). 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.