Background: Although frequently used to track health care disparities, patient race/ethnicity data collected by hospitals can be unreliable, particularly for smaller minority groups. We sought to determine whether the racial/ethnic distribution of hospitalized patients shifted after implementation of a statewide initiative to standardize data collection practices.
Methods: We conducted a difference-in-differences analysis of the State Inpatient Databases to estimate changes in the proportion of patients identified as non-Hispanic white, non-Hispanic black, Hispanic, Asian/Pacific Islander, and "other," before (2005-2006) and after (2008-2009) standardized practices were implemented in New Jersey relative to New York, a state with similar demographics but no changes to data collection.
Results: Among 12,552,702 hospital discharges, modest relative changes were noted in the proportion of patients identified as non-Hispanic white [+1.1%; 95% confidence interval (CI): +0.9 to +1.2] and non-Hispanic black (+1.6%; 95% CI: +1.1 to +2.1) in New Jersey that were attributed to its use of standardized data collection practices as compared with New York. Larger relative changes were noted in the proportion of patients identified as Hispanic (-7.1%; 95% CI: -7.8 to -6.4), Asian/Pacific Islander (+26.5%; 95% CI: +25.1 to +27.9), and "other" (-24.6%; 95% CI: -26.4 to -22.8). This pattern was largely consistent in analyses stratified by sex, age, and Major Diagnostic Category.
Conclusions: Measurement of health care disparities fundamentally depends on the racial/ethnic categorization of individuals. By redistributing substantial proportions of patients across smaller minority groups, standardized data collection could lead to shifts in estimates of health care disparities for these rapidly growing populations.