Background:Previous studies evaluating the epidemiology of pelvic ring fractures and predictors of mortality are largely based upon non-US populations, potentially limiting their generalizability. This study sought to analyze trends of pelvic ring fractures and associated complications in the United States using the largest and most recent national data set available. The specific aims of this study were to determine whether the incidence of pelvic ring fractures changed over time, whether in-hospital mortality following pelvic ring fracture changed over time, whether hospital length of stay following pelvic ring fracture changed over time, and whether there are independent predictors of in-hospital mortality, adverse events, or nonroutine discharge following pelvic fracture.Methods:The National Hospital Discharge Survey was queried to identify all patients admitted to US hospitals with pelvic ring fractures between 1990 and 2007. A cohort representative of 1 464 458 patients was identified, and multivariable logistic regression was used to find independent predictors of mortality, adverse events, and nonroutine discharge to another inpatient facility.Results:Between 1990 and 2007, the population-adjusted incidence of pelvic ring fractures increased from 27.24 to 34.30 per 100 000 capita (P < .001). Mortality declined from 4.2% to 2.8% (P < .001) paralleling an increase in the proportion of patients treated with surgical fixation (7.22%-10.36%). All forms of internal fixation were associated with decreased odds of mortality, while external fixation was associated with increased odds of mortality. Internal fixation was also associated with lower odds of adverse events and nonroutine discharge to inpatient facilities. The average in-hospital length of stay decreased from 11.2 days to 6.5 days (P < .001).Conclusion:This study provides the largest and most comprehensive epidemiologic analysis of pelvic ring fractures in the United States. Knowledge of the increasing incidence of pelvic fractures and prognostic factors associated with poor outcomes may improve outcomes.