Minimum clinically important difference in outcome scores among patients undergoing cervical laminoplasty

Minimum clinically important difference (MCID) represents the smallest change in an outcome measure recognized as clinically meaningful to a patient and is one of the most important psychometric parameters for assessing the postoperative results of spinal surgery. The purpose of the present study was to elucidate MCIDs for four common outcome measures used for degenerative cervical myelopathy in the context of patients undergoing laminoplasty.

We retrospectively reviewed a consecutive series of cervical laminoplasties in a single academic institution. Pre- and postoperative Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), Short Form-36 (SF-36), Neck Disability Index (NDI), and EuroQOL (EQ-5D) scores were obtained. Patients were also asked to answer the anchor question regarding satisfaction with treatment, and the anchor-based method was used to determine cut-off values for MCIDs.

A total of 101 patients were included in the analysis. All outcome scores showed significant improvement postoperatively, with the exception of JOACMEQ bladder function score and SF-36 mental component summary score. Most patients (66%) were at least "somewhat satisfied" with treatment results. Receiver operating characteristic curve analyses revealed MCIDs of 2.5 for JOACEMQ cervical spine function, 13.0 for upper extremity function, 9.35 for lower extremity function, 9.5 for QOL, 3.9 for SF-36 physical component summary score, 4.2 for NDI, and 0.0485 for EQ-5D.

The MCIDs of four outcome measures were determined for patients undergoing cervical laminoplasty. These slides can be retrieved under Electronic Supplementary Material.