Socio-economic inequality in unhealthy snacks consumption among adolescent students in Iran: a concentration index decomposition analysis

Objective: The present study aimed to assess and decompose the socio-economic inequality in unhealthy snacks consumption among adolescent students in Kerman, Iran. Design: The data were obtained from a cross-sectional study. Principal component analysis was done to measure the socio-economic status (SES) of the adolescents' families and the normalized concentration index (NCI) was used to measure the inequality in unhealthy snacks consumption among adolescent students of different SES. The contributions of environmental and individual explanatory variables to inequality were assessed by decomposing the concentration index. Setting: Forty secondary schools of Kerman Province in Iran in 2015. Participants: Eighth-grade adolescent students (n 1320). Results: The data of 1242 adolescent students were completed for the current study. Unhealthy snacks consumption was unequally distributed among adolescent students and was concentrated mainly among the high-SES adolescents (NCI = 0 center dot 179; 95 % CI 0 center dot 056, 0 center dot 119). The decomposition showed that higher SES (62 %) and receiving pocket money allowance (31 %), as environmental variables, had the highest positive contributions to the measured inequality in unhealthy snacks consumption. Taste and sensory perception (7 %) as well as cost sensitivity (5 %), as individual variables, followed them in terms of their contribution importance. Conclusions: It is highly suggested that both environmental and individual factors should be addressed at different settings including schools, families and suppliers of unhealthy snacks. These findings can help future health promotion strategies in Iran to tackle the observed inequality in unhealthy snacks consumption.