Incidence of second cervical vertebral fractures far surpassed the rate predicted by the changing age distribution and growth among elderly persons in the United States (2005-2008)

Study Design: Nationwide epidemiological cohort study. Objective: To characterize the incidence of second cervical vertebral (C2) fractures by age and geographical region among the elderly Medicare population and to elucidate if the rate changed in the years 2005 to 2008. Summary of Background Data: Recent publications hypothesized that the rate of cervical vertebral fractures may be increasing. To date, there are no published nationwide reports describing the incidence and demographics of these injuries in the elderly US population. Methods: Incidence of C2 fracture in the years 2005 to 2008 was determined by querying PearlDiver Technologies, Inc. (Warsaw, IN), a commercially available database, using International Classifi cation of Diseases code 805.02. Rates were calculated using the PearlDiver reported person-counts as the numerator and the Center for Medicare and Medicare Services midyear population fi le as the denominator, and reported per 10,000 person-years (10,000 p-y). The age and geographical distributions of fractures were examined. Variability in rates was analyzed using the mean, standard deviation, 95% confi dence intervals, ÷ 2 tests, and Pearson correlation coeffi cients. Results: Although the elderly population increased by 6% between 2005 and 2008, the annual incidence of C2 fracture rose by 21%, from 1.58 to 1.91 per 10,000 p-y, trending upward in a straightline function (r = 0.999, P = 0.0006). The incidence of fracture varied between age groups; however, an increase was observed in all age groups. Persons aged 65 to 74 years (the youngest age group) experienced the lowest incidence (0.63 in 2005 to 0.71 in 2008), and the rate of increase was the smallest among the age groups examined (13%). Persons aged 85 and older demonstrated the highest incidence (4.36-5.67) and the greatest increase (30%). Conclusion: From 2005 to 2008, the overall incidence of C2 fracture rose at a rate that was 3.5 times faster than the elderly population growth.