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Adjacent segment disease

Biomechanics

cervical spondylosis

cranial-cervical junction, C1, C2

cervical spondylotic myelopathy

cervicalgia

C5 Palsy

OPLL

cervical herniated disc

thoracic herniated disc

lumbar degeneration

lumbar herniated disc

peripheral nerve

deformity

Extradural tumor

Intradural extramedullary tumor

Intramedullary tumor

spinal fusion

osteoporosis

Levels of Evidence For clinical research (As Adopted by the North American Spine Society January 2005)

	Therapeutic Studies	Prognostic Studies	Diagnostic Studies	Economic and Decision Analyses
Level 1	• High quality randomized trial with statistically significant difference or no statistically significant difference but narrow confidence intervals • Systematic Review of Level I RCTs and study results were homogenous	• High quality prospective study (all patients were enrolled at the same point in their disease with ≥ 80% follow-up of enrolled patients) • Systematic review of Level I studies	• Testing of previously Developed diagnostic criteria on consecutive patients • Systematic review of Level I studies	• Sensible costs and alternatives; values obtained from many studies; with multi way sensitivity analyses • Systematic review of Level I studies
Level 2	• Lesser quality RCTs • Prospective comparative study • Systematic review of Level II studies or Level I studies with inconsistent results	• Retrospective study • Lesser quality prospective study (e.g. patients enrolled at different points in their disease) • Systematic review of Level II studies	• Development of diagnostic criteria on consecutive patients (with universally applied reference “gold” standard) • Systematic review of Level II studies	• Sensible costs and alternatives; values obtained from limited studies; with multiway sensitivity analyses • Systematic review of Level II studies
Level 3	• Case control study • Retrospective comparative study • Systematic review of Level III studies	• Case control study	• Study of nonconsecutive patients; without consistently applied reference “gold” standard • Systematic review of Level III studies	• Analyses based on limited alternatives and costs; and poor estimates • Systematic review of Level III studies
Level 4	• Case Series	• Case Series	• Case Series Poor reference standard	• Analyses with no sensitivity analyses
Level 5	• Expert Opinion	• Expert Opinion	• Expert Opinion	• Expert Opinion