Natural history of degenerative cervical myelopathy: a meta-analysis and neurologic deterioration survival curve synthesis

BACKGROUND CONTEXT Cervical spine surgery is rapidly increasing, and our knowledge of the natural history of degenerative cervical myelopathy (DCM) is limited. PURPOSE To synthesize accurate time-based estimates of meaningful neurologic decline in patients with DCM managed conservatively and to provide formulae to help communicate survivorship estimates to patients. STUDY DESIGN Systematic review and meta-analysis. METHODS A systematic review and meta-analysis was conducted using Cochrane and PRISMA guidelines. A librarian-assisted search strategy using multiple databases with broad search terms and validated filter functions was used. All articles were reviewed in duplicate. RESULTS A total of 9570 studies were captured in the initial search, which after deletion of duplicates and manual review of abstracts and full texts revealed 6 studies for analyses. All studies were prospective cohorts or randomized controlled trials. The pooled survival estimates for neurologic stability (95% CrI) for mild DCM patients are: 91% (83%–97%) at one year; 85% (72%–94%) at 2 years; 84% (70%–94%) at 3 years; 75% (54%–90%) at 5 years; 66% (40%–86%) at 15 years; and 65% (39%–86%) at 20 years. The pooled survival estimates for neurologic stability (95% CrI) for moderate/severe DCM patients are: 83% (76%–89%) at 1 year; 72% (62%–81%) at 2 years; 71% (60%–80%) at 3 years; 55% (41%–68%) at 5 years; 44% (27%–59%) at 15 years; and 43% (25%–58%) at 20 years. CONCLUSIONS This is the first quantitative synthesis of the totality of published data on DCM natural history. Our review confirms a slow decline in neurologic function. We developed formulae which can be easily used by surgeons to communicate to patients their risk of neurologic deterioration. These formulae can be used to facilitate the shared decision-making process.