Modification of Nurick scale and Japanese Orthopedic Association score for Indian population with cervical spondylotic myelopathy

Abstract

Aims: Existing scales for functional grading of patients with cervical spondylotic myelopathy (CSM), such as the Nurick scale and modified Japanese Orthopedic Association (mJOA) scale, do not address certain culture-specific activities of the Indian population while grading patients with CSM.

Materials and methods: We modified the Nurick scale and mJOA scale to develop the Indian modifications of Nurick (imNurick) and mJOA scales (imJOA and imJOA scales), respectively, and then evaluated these modified scales in 93 patients with CSM to determine whether these modifications had a meaningful impact on the functional scores of these patients.

Results: There was good interobserver agreement in the assessments documented in all the four scales (Nurick grade, imNurick grade, mJOA scale, and imJOA scale) (kappa = 1). Both Nurick grading (z = 4.4, P = 0.00) and imNurick grading (z = 5.5, P = 0.00) had a valid construct when tested against lower limb mJOA (llmJOA) score. The Indian modified upper limb JOA (imulmJOA) score too had a good construct with modified upper limb JOA (ulmJOA) score (z = 2.5, P = 0.01). There was substantial agreement between Nurick grade and imNurick grade (weighted kappa of 0.75) when taken as a whole group and between ulmJOA score and imulmJOA scores (weighted kappa of 0.75). However, there was significant disagreement between the Nurick grade and imNurick grade scales in patients who were Nurick grade 2 and 3 (kappa = 0.07).

Conclusions: The proposed Indian modifications of Nurick grade and mJOA scale that incorporate the ethnic practices of the Indian population and some Asian population are better discriminators of different levels of functional ability among patients with CSM in this population, as compared to the existing Nurick grading and mJOA scale.