Table 8

Limitations of Database--Nationwide Inpatient Sample from years 2001 to 2010.

CategoryLimitation
Disease Severity
  • Cannot indicate severity of pre-operative CSM

  • Cannot identify or weigh differently the variation in neurologic function

  • Nurick, Frankel, JOA, or Ducker Motor Index quantitative assessment of neurologic involvement unavailable

  • Presence or absence of myelomalacia is not controlled for

Surgical Approach
  • Laminoplasty versus laminectomy differentiation using ICD-9-CM codes is difficult

  • NIS database does not list the presence nor the type of spinal instrumentation

  • NIS database pools together one-level surgeries with multi-level, including 5-level, operations.

  • The number of surgical vertebral levels has an impact on outcomes and it is expected that the combined anterior-posterior group has the highest number of multilevel cases.