Associations of body mass index and body height with low back pain in 829,791 adolescents.

Body mass index (BMI) (calculated as weight (kg)/height (m)²) and height are linked to the pathogenesis of low back pain, but evidence-based confirmation is lacking. We examined the prevalence of low back pain in adolescents and its association with BMI and height. Disability clauses (official military limitations related to a person's health status) indicating low back pain severity were divided according to symptoms of low back pain alone and symptoms of low back pain with objective corroborating findings. All 829,791 males and females undergoing mandatory premilitary recruitment examinations since 1998 were included. Logistic regression models assessed the relationships of BMI and height with low back pain. Prevalence of low back pain was 0.2% for both males and females with objective findings and 5.2% for males and 2.7% for females without objective findings. Higher BMI was significantly associated with low back pain in males (for overweight, odds ratio = 1.097, P < 0.001; for obese, odds ratio = 1.163, P < 0.001) and in females (for overweight, odds ratio = 1.174, P < 0.001; for obese, odds ratio = 1.211, P < 0.001). Height was associated with increased risk of low back pain in both genders. Odds ratios for low back pain in the tallest group compared with the shortest group were 1.438 (P < 0.001) for males and 1.224 (P < 0.001) for females. Low back pain with or without objective findings was associated with overweight and obesity as well as with height.