The Crush Index: Orthopedic Trauma as an Economic Indicator

The purpose of this study was to evaluate the relationship between economic activity and the incidence of high-energy orthopedic trauma. California's Office of Statewide Health Planning and Development patient discharge database was queried to identify monthly orthopedic trauma incidence from 1995 to 2010. Patient inclusion required 1 diagnosis code and 1 associated procedural code for fractures of the femur, tibia, ankle, pelvis, or acetabulum. Data on composite market indices, energy and transportation use, and unemployment were obtained from government sources. Statistical analysis was performed using univariate and multivariate linear regression. The average monthly incidence of orthopedic trauma was 2.92 cases per 100,000 people. Of 15 economic indicators analyzed with univariate regression, 7 variables correlated with trauma incidence to statistical significance. Dow Jones Industrial Average (P=.032), Standard & Poor's 500 (P=.034), vehicle miles driven (P<.001), personal disposable income (P=.033), Coincident Economic Activity Index for California (P=.007), and vehicles purchased (P<.001) were positively correlated with trauma incidence. Unemployment (P<.001) was inversely correlated with trauma incidence. Multivariate regression was used to compute a combination of independent predictors of trauma volume: personal disposable income (P<.001), vehicles purchased (P=.008), and unemployment (P=.005). This combination of variables was used to develop the Crush Index to model the relationship between economic activity and orthopedic trauma volume. The authors show a positive correlation between economic strength and activity and the monthly volume of high-energy orthopedic trauma. The Crush Index serves as a proof of concept that may be useful in guiding preparedness among practitioners and health care system administrators.