Functional level of lesion scale: Validating fourteen years of research with the national spina bifida patient registry

PURPOSE: Functional level of lesion (FLOL) is a grading of the level of neurological function in patients with myelomeningocele and other forms of spina bifida. It has been widely used as an independent variable in studies of spina bifida, but its inter-rater reliability has not previously been tested. The purpose of this study was to measure inter-rater reliability of FLOL testing and compare testing performed by a non-medically trained research associate to testing performed by a pediatric rehabilitation medicine specialist. METHODS: Children in a multi-disciplinary spina bifida clinic underwent FLOL grading by a non-medically trained research associate. On the same day, these children were also graded by a pediatric rehabilitation medicine specialist. Cohen’s weighted kappa statistic was used to compare grading, with the rehabilitation medicine specialist considered the gold standard. RESULTS: A total of 71 patients participated. FLOL was graded for left and right leg for each participant, resulting in 142 measurements. Cohen’s weighted kappa was κ= 0.809, with a standard error of 0.034 and 95% confidence interval 0.723–0.875, indicating substantial agreement. CONCLUSION: FLOL as measured according to the instructions of the National Spina Bifida Patient Registry by a non-medically trained researcher is a reliable method to grade lower extremity function in spina bifida.