['What risk factors have been identified for the first episode of low back pain in children and adolescents? Have these risk factors been validated?', 'Systematic review of prospective studies designed to identify possible modifiable and non-modifiable risk factors for the onset of low back pain in children and adolescents.', 'School children aged up to 18 years without low back pain at enrolment.', 'Five studies were included in the review. The included studies varied considerably in methods used to gather data, definitions of low back pain, and recall periods for an episode of low back pain. Forty-seven possible risk factors had been assessed for association with a first episode of low back pain in children. Of these, 13 were significantly associated with a first episode of low back pain. No risk factor was found to be associated with future low back pain in children in more than one study.'] Are risk factors for the first episode of low back pain in children infrequently validated across samples and conditions : a systematic review?