Research Inefficiency in Degenerative Cervical Myelopathy: Findings of a Systematic Review on Research Activity Over the Past 20 Years

STUDY DESIGN: Scoping review. OBJECTIVE: To describe activity, themes and trends in degenerative cervical myelopathy (DCM) research over the past 20 years with a view to considering DCM research inefficiency. METHODS: A systematic review of MEDLINE and Embase for “Cervical” AND ”Myelopathy” was conducted following PRISMA guidelines. Full-text papers in English, exclusively studying DCM, published between January 1, 1995 and December 31, 2015 were considered eligible. Country of origin, number of papers published, number of patients studied, research theme, and year of publication were assessed. Comparison was made between developed and developing countries. RESULTS: A total of 1485 papers and 4 117 051 patients were included. Japan published more papers (450) than any other country while the United States studied the greatest number of patients (3 674 737). Over 99.4% of papers and 78.6% of patients were from developed countries. The number of papers (r = 0.96, P < .001) and patients (r = 0.83 P < .001) studied each year increased significantly overall and for both developed (r = 0.93, P < .001; r = 0.81, P < .001) and developing countries (r = 0.90, P < .001; r = 0.87, P < .001). Surgery was the most prevalent theme (58.3% papers; 55.7% patients) for developed and developing countries. Research from developing countries showed greater thematic variability. CONCLUSIONS: DCM research activity is increasing internationally, with surgery remaining the focus. Research output has predominantly been from developed countries; however, the rate of growth for developed and developing countries is comparable.