Longitudinal risk factors for persistent fatigue in adolescents

Objective: To examine whether sedentary behavior, obesity, smoking, and depression are risk factors for persistent fatigue in adolescents. Design: Longitudinal population-based survey. Setting: Twenty-eight randomly selected schools in east London, England, in 2001 and 2003. Participants: A total of 1880 adolescents (49% male; 81% nonwhite British) aged 11 to 12 years and 13 to 14 years in 2000. Intervention: Confidential questionnaires completed in class. Main Outcome Measures: Persistent fatigue (extreme tiredness twice weekly or more often in the previous month at both surveys), sedentary behavior, physical activity, depressive symptoms, body mass index, and smoking. Results: Severe fatigue was reported in 11% of participants aged 11 to 14 years and 17% of participants aged 13 to 16 years. Eighty-four participants (4%) reported persistent fatigue. Across both surveys, only 3 pupils reported chronic fatigue syndrome. In multivariate logistic regression, risk of persistent fatigue was independently associated with being sedentary for more than 4 hours per day (odds ratio = 1.6; 95% confidence interval, 1.1-2.3; P=.01), being physically active (odds ratio=1.5; 95% confidence interval, 1.1-2.3; P=.004), and depressive symptoms (odds ratio=2.0; 95% confidence interval, 1.5-2.7; P<.001) in the first survey, after adjustment for age, sex, and socioeconomic status. Obesity and smoking were not associated with fatigue. Conclusions: Persistent fatigue is common. Being highly sedentary or highly active independently increased the risk of persistent fatigue, suggesting that divergence in either direction from healthy levels of activity increases the risk for persistent fatigue. Mental health is important in the etiology of persistent fatigue. To help define effective preventive strategies, further work is needed on the mechanisms by which these factors contribute to fatigue.