Trends and variations in cervical spine surgery in the United States: Medicare beneficiaries, 1992 to 2005.

STUDY DESIGN: Retrospective cohort.

OBJECTIVE: To describe population-based trends and variations in surgery for degenerative changes of the cervical spine among Medicare beneficiaries, 1992 to 2005.

SUMMARY OF BACKGROUND DATA: Degenerative changes of the cervical spine are seen radiographically in over half of the population aged 55 years or greater, and rates of cervical spine surgery have increased over time. Prior studies examined anterior cervical discectomy and fusion procedures in the general population up to 1999, and showed regional variations in care, with the highest rates in the South. The purpose of this study is to explore population-based trends and variations in surgery for degenerative changes of the cervical spine in the elderly.

METHODS: From 1992 to 2005, hospital admissions associated with surgery for degenerative changes of the cervical spine were selected from Medicare Part A using ICD9 CM codes. We excluded beneficiaries under 65 years of age, in a capitated health plan, or enrolled for Social Security Disability Income. Diagnosis and type of surgery were defined using ICD9 CM codes. Rates were directly adjusted to age, sex, and race of 2005 Medicare beneficiaries.

RESULTS: Of 156,820 qualifying admissions, 52% were men, 88% were white, and 41% were aged 65 to 69 years. The most common primary diagnosis and procedure were cervical spondylosis with myelopathy (36%) and fusion (70%); of the fusions, 58% were anterior. Rates of cervical fusions rose from 1992 to 2005 even after adjustment for age, sex, and race (14.7 to 45 cervical fusions/100,000 beneficiaries). Rates of cervical fusions varied by geographic location, with the highest rates in the Northwest and South Central regions. In 2005, the highest rate of cervical fusions was 140/100,000 beneficiaries in Idaho, compared with 4/100,000 beneficiaries in Washington, DC.

CONCLUSION: In the elderly, adjusted rates of cervical spine fusions rose 206% from 1992 to 2005. Marked geographic variation was noted. Future studies should evaluate the efficacy and complications associated with these procedures in the elderly, and better define surgical indications and patient outcome.