A Comparison of Diagnostic Stability of the ASIA Impairment Scale Versus Frankel Classification Systems for Traumatic Spinal Cord Injury

Objective: To determine whether the “sacral sparing” definition for completeness of traumatic spinal cord injury (SCI) is a more stable definition than the previously used Frankel Classification. Design: Retrospective analysis of individuals enrolled in the Spinal Cord Injury Model Systems (SCIMS) database between 2011 and 2018. Setting: SCIMS centers. Participants: Individuals (N=804) with traumatic SCI who were at least 16 years old at time of injury, were admitted to rehabilitation within 30 days, had American Spinal Injury Association Impairment Scale (AIS) grades A-D at admission, and had complete neurologic data at the time of admission and 1 year. Intervention: Not applicable. Main Outcome Measures: Frankel and AIS scores were computed for a cohort of 804 eligible cases. Stability was compared between the 2 classification systems by calculating the proportions of cases in which regression (conversion to a more severe impairment level) was observed. Results: A larger proportion of individuals classified with “incomplete” injuries (grades B-D) at the time of admission using the Frankel system regressed to complete status at 1 year compared with the AIS criteria (9.4% vs 2.0%). Those with grade B injuries regressed to grade A more often using the Frankel system compared with the AIS system (19.7% to 5.4%). A larger proportion of people diagnosed as Frankel grade C or D regressed to Frankel grade A compared with individuals diagnosed as AIS grade C or D who regressed to AIS grade A (5.0% to 1.1%). Conclusions: More individuals diagnosed with neurologically incomplete SCI regressed to complete status at 1 year when using the Frankel system compared with AIS classification, which is based on sacral sparing. This reinforces the finding that the “sacral sparing” definition is a more stable classification in traumatic SCI.