Reliability in grading the severity of lumbar spinal stenosis

Stenosis of the lumbar spinal canal is a major cause of disability and lost productivity. Computed tomography (CT) is used commonly to assess the pres ence and severity of spinal stensosis, because it is relatively inexpensive , readily available, and has few adverse effects. The ability of four surge ons to agree about the presence and severity of lumbar spinal stenosis base d on plain CT scans was evaluated from 30 scans of varying stenosis severit y (normal to severe). Kappa, a measure of chance-corrected agreement, was c alculated. Surgeons exhibited moderate agreement for the presence or absenc e of spinal stenosis (kappa = 0.58 +/- 0.06). Agreement regarding the sever ity of stenosis, when present, was poor (kappa = 0.26 +/- 0.04). The abilit y of surgeons to agree was not improved when individual features of the CT scans were assessed (facet joint arthrosis, ligamentum flavum hypertrophy, disk protrusion, and nerve root impingement). This study suggests that CT s cans are not a reliable method by which to examine the severity of lumbar s pinal stenosis.