Incidence of Pelvic Ring Fractures in the U.S. Military Population

Introduction  Pelvic ring fractures occur frequently among the elderly population, but some studies demonstrate a bimodal distribution where the incidence is elevated among younger age groups as well. The mechanisms of injury also vary based on age groups. Previous studies are specific to trauma registries and centers, but epidemiological data within the U.S. military are sparse. In the U.S. military population, pelvic ring fractures can be related to high-energy trauma including motor vehicle accidents and combat warfare. The purpose of this study was to determine the incidence of pelvic ring fractures among active duty U.S. military service members between 2006 and 2015, while also describing the demographics associated with the findings. Materials and Methods All data were collected from the U.S. Defense Medical Epidemiology Database (DMED). To calculate the incidence rates, only first-time occurrences for pelvic ring fractures among military members were used. Each point was identified using International Classification of Diseases, Ninth Revision (ICD-9), clinical modification code 808 for "fractures of the pelvis." A multivariate Poisson regression analysis was used to estimate the incidence rate per 1,000 person-years and 95% confidence intervals while controlling for sex, race, age, rank, and service. Rate ratios were calculated using different referent factors based on differences in sex, race, age, rank, and service branch. This study was IRB exempt as all the data used were de-identified patient data from the DMED system. Results Over the 10-year study period, a total of 4,802 incident cases of pelvic ring fractures, and a total of 13,748,429 person-years were documented. The overall incidence rate of pelvic ring fractures was 0.35 per 1,000 person-years. The incidence of pelvic ring fractures was highest among the youngest age group (<20 years) and among the lower-ranking service members. Additionally, other demographic groups such as the White race, female sex, and Army service members showed the highest incidence rates. Conclusion Our study determined baseline epidemiological data on incidence rates of pelvic ring fractures in the U.S. military. Patient demographics may be contributing factors, and the present analysis was able to elucidate associated underlying demographics. We demonstrated that the incidence was highest among the younger age groups, and that incidence rates may be specific to age cohorts. This study also found that lower-ranking service members had the highest incidence in all service branches, suggesting a form of occupational risk. Furthermore, our findings suggest that females, White race groups, and Army enlisted service members show a significantly higher incidence rate and may be at a greater risk. Our findings are important as they broaden the understanding of the patterns of pelvic ring fractures in the U.S. military population and occupational risks associated with this population.