Non-linear formulas for the spinal cord injury ability realization measurement index

The spinal cord injury ability realization measurement index (SCI-ARMI) assesses rehabilitation potential and efficacy based on the linear relationship between the Spinal Cord Independence Measure (SCIM) and the American Spinal Injury Association impairment scale (AIS) motor scores (AMS).

The objective of this study is to develop new SCI-ARMI formulas using a more flexible approach that is less sensitive to the distribution of the AMS score among spinal cord lesion (SCL) patients.

Loewenstein Rehabilitation Hospital, Raanana, and the Statistical Laboratory, School of Mathematics, Faculty of Exact Sciences, Tel-Aviv University, Israel.

SCIM III and AMS of 226 Israeli SCL patients were monitored. Linear formulas, quadratic formulas and non-parametric formulas were estimated to express the relationship between the 95th percentile of the SCIM III values for patients with given AMS at discharge from rehabilitation (SCIM95) and the corresponding AMS value. This relationship was used to calculate SCI-ARMI values, defined as the ratio of the observed SCIM score and the respective SCIM95 for a given patient's AMS score.

The estimated quadratic formula for the relationship between the 95th percentile of the SCIM III and the AMS score was found to be most appropriate, and formulas are provided for SCIM95 calculation in the various areas of function. The use of these formulas to calculate SCI-ARMI values is presented.

The new formulas improve the accuracy of calculated ability realization for any AMS. The new statistical procedure will be used for the upcoming data analysis of a larger-scale international SCI-ARMI study.