Factors Associated With Ambulation in Myelomeningocele: A Longitudinal Study From the National Spina Bifida Patient Registry.

OBJECTIVE

Evidence is limited regarding clinical factors associated with ambulation status over the lifespan of individuals with myelomeningocele. We used longitudinal data from the National Spina Bifida Patient Registry to model population-level variation in ambulation over time and hypothesized that effects of clinical factors associated with ambulation would vary by age and motor level.

DESIGN

A population-averaged generalized estimating equation was used to estimate the probability of independent ambulation. Model predictors included time (age), race, ethnicity, sex, insurance, and interactions between time, motor level, and the number of orthopedic, noncerebral shunt neurosurgeries, and cerebral shunt neurosurgeries.

RESULTS

The study cohort included 5371 participants with myelomeningocele. A change from sacral to low-lumbar motor level initially reduced the odds of independent ambulation (OR = 0.24, 95% CI = 0.15-0.38) but became insignificant with increasing age. Surgery count was associated with decreased odds of independent ambulation (orthopedic: OR = 0.65, 95% CI = 0.50-0.85; noncerebral shunt neurosurgery: OR = 0.65, 95% CI = 0.51-0.84; cerebral shunt: OR = 0.90, 95% CI = 0.83-0.98), with increasing effects seen at lower motor levels.

CONCLUSIONS

Our findings suggest that effects of several commonly accepted predictors of ambulation status vary with time. As the myelomeningocele population ages, it becomes increasingly important that study design account for this time-varying nature of clinical reality.

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OBJECTIVES

Upon completion of this article, the reader should be able to: (1) Describe general trends in ambulation status by age in the myelomeningocele population; (2) Recognize the nuances of cause and effect underlying the relationship between surgical intervention and ambulation status; (3) Explain why variation of clinical effect over time within myelomeningocele population matters.

LEVEL: Advanced ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.