ASIA impairment scale conversion in traumatic SCI: is it related with the ability to walk? A descriptive comparison with functional ambulation outcome measures in 273 patients.

STUDY
DESIGN: Prospective multicenter longitudinal cohort study.
OBJECTIVES: To determine the relationship between improvements of the American Spinal Injury Association/International Spinal Cord Society (ASIA/ISCoS) neurological standard scale (AIS) outcome measure and improvements of functional ambulatory outcome measures in patients with traumatic spinal cord injury (SCI).
SETTING: European multicenter study of human SCI (EM-SCI).
METHODS: In 273 eligible patients with traumatic SCI, acute (0-15 days) and chronic phase (6 or 12 months) AIS grades, timed up and go (TUG) test and 10-m walk test (10MWT) outcome measurements were analyzed. Subanalysis of those patients who did have AIS conversion was performed to assess its relation with functional ambulatory outcomes.
RESULTS: Studied population consisted of 161 acute phase AIS grade A patients; 37 grade B; 43 grade C and 32 acute phase AIS grade D patients. Forty-two patients (26%) converted from AIS grade A, 27 (73%) from grade B, 32 (75%) from grade C and five patients (16%) from AIS grade D. The frequencies of AIS conversions and functional ambulation recovery outcomes were significantly different (P<0.001) in patients with motor complete SCI. The ratio of patients with both recovery of ambulatory function and AIS conversion (n=101) differed significantly (P<0.001) between the acute phase AIS grade scores; AIS grade A (6/40 patients, 15%), B (9/27 patients, 33%), C (23/29 patients, 79%) and D (5/5 patients 100%).
CONCLUSIONS: The AIS conversion outcome measure is poorly related to the ability to walk in traumatic SCI patients. Therefore, the authors recommend the use of functional ambulation recovery outcome measures in prognosticating the recovery of walking capacity and performance of patients with SCI.