Association Between Body Mass Index and Nonspecific Recurrent Low Back Pain in Over 600,000 Healthy Young Adults.

An association between body mass index (BMI; weight (kg)/height (m)2) and low back pain (LBP) has long been debated, but inconsistent measurements of BMI and varying definitions of LBP have produced conflicting findings. We explored this association using measured BMI and physician documentation of recurrent LBP among healthy young adults. Data were extracted from the Israel Defense Forces electronic medical record system. All Israeli citizens with compulsory military service during January 2008-March 2019 were included (n = 705,840). Exclusion criteria were spine deformities, disc pathologies, spinal surgeries, arthropathies, connective tissue diseases, pain syndromes, low bone density disorders, cancers, and psychiatric illnesses. LBP was defined as electronic medical record system documentation of 1) 2 medical visits at least 6 weeks apart with a diagnosis of LBP or "LBP with radiation" or 2) 1 medical visit resulting in referral to an orthopedic surgeon. Logistic regression models were used to explore the association between BMI category and LBP; 619,969 (87.8%) individuals (mean age = 18.9 (standard deviation, 0.97) years; 56.9% male) were included. LBP prevalence was 9.2% (n = 56,918) and higher among males (9.7%) than females (8.5%). Overweight (odds ratio = 1.123, 95% confidence interval: 1.096, 1.151) and obesity (odds ratio = 1.137, 95% confidence interval: 1.096, 1.179) were associated with LBP. The association remained significant after accounting for various sociodemographic factors. Maintaining a healthy BMI may aid in the prevention of LBP in young adults.