Table 2. ICD-9 codes for chronic low back pain sample.

ICD-9 Codes	Number of Patients
Lumbago (724.2)	18
Backache Unspecified (724.5)	7
Sciatica (724.3)	4
Thoracic or Lumbosacral Neuritis or Radiculitus (724.4)	3
Non Allopathic Lesions of Lumbar Region (739.3)	2
Post Laminectomy Syndrome of Lumbar Region (722.83)	1
Lumbar Disc Displacement without Myelopathy (722.1)	1

ICD-9 = International Classification of Diseases