Co-occurrence and clustering of the four major non-communicable disease risk factors in Brazilian adolescents: Analysis of a national school-based survey.

backgroundThe major non-communicable chronic diseases (NCD) are associated with a small group of modifiable lifestyle-related risk factors, including smoking, insufficient physical activity, unhealthy eating, and alcohol abuse. In this study, we evaluated the co-occurrence and clustering of the major NCD risk factors among Brazilian adolescents.

methodsThis cross-sectional study analyzed data of 101,607 adolescents from the Brazilian National Survey of School Health (PeNSE) 2015. The risk factors included were: regular consumption of ultra-processed foods, irregular consumption of fruits and vegetables, insufficient physical activity, smoking, and alcohol consumption. Clustering was defined through the ratio between observed and expected prevalences of combination of risk factors greater than 1. Expected prevalence of the co-occurrence of risk factors was calculated from the joint probability of the behaviors. Additionally, we examined the presence of at least four risk factors according to socioeconomic characteristics.

resultsOf the 32 combinations of risk factors, 13 corresponded to clustering. We observed a strong correlation between alcohol consumption and smoking, which were found together in 8 of the 13 clusters identified. The most frequent combinations of risk factors involved unhealthy eating and insufficient physical activity. Only 2.9% of the adolescents did not present any risk behaviors, while 38.0%, 32.9%, 9.4% and 1.8% accumulated two, three, four and five risk factors, respectively. The accumulation of risk factors was higher in girls, older adolescents, those who did not live with both parents, children of less-educated mothers, students attending public school, and residents of cities in more developed urban areas of the country.

conclusionsThe main risk factors for NCD are frequent and not randomly distributed among Brazilian adolescents. Our results provide information for policymakers to target specific groups and joint behavioral risk factors for health improvement in adolescents.