Adiposity trajectory as a predictor of chronic and multisite pain in the transition from childhood to adolescence: A prospective study of a large birth cohort.

BACKGROUND/OBJECTIVES: The association between obesity and pain may have relevant population health implications starting in young ages. We aimed to quantify associations between adiposity and pain in the general population, from 4 to 13 years of age, using complementary longitudinal approaches. METHODS: Participants were from Generation XXI, a population-based cohort assembled at birth in Porto, Portugal, and re-evaluated at 4, 7, 10, and 13 years of age (n = 4563). Pain was assessed using the Luebeck Pain Questionnaire and classified as chronic (above three months) or multisite (two or more sites). Adiposity parameters included fat mass percentage and age- and sex-standardized body mass index scores (BMI z-scores). Associations between individual adiposity trajectories from ages 4 to 13, extracted from mixed-effects polynomial trend models, and pain measures at age 13 were tested using logistic regression adjusted for pubertal development and practice of programmed physical activity. Bidirectionality was assessed using cross-lagged analysis. RESULTS: Among girls, quadratic fat mass (FM) trajectories, characterized by accelerated fat mass gain, were associated with increased odds of chronic pain (quadratic coefficient odds ratio [ OR F M 2 ] = 1.37, 95% confidence interval [CI]: 1.12, 1.69) and multisite pain ( OR F M 2  = 1.27, 95% CI: 1.05, 1.53) at age 13. Consistently, results from the cross-lagged analysis in girls suggest associations between adiposity at age 10 and pain reports at age 13. Among boys, only suggestive associations emerged, particularly for the quadratic BMI z-score trajectories with chronic pain ( OR B M I z 2 :1.34, 95% CI: 0.96, 1.86). CONCLUSION: Higher adiposity during childhood and early adolescence was a predictor of chronic and multisite pain reports at age 13 among girls.