OBJECTIVES: Reports of racial/ethnic disparities in healthcare quality and outcomes typically do not distinguish between within-hospital and between- hospital mean effects. If Black patients have lower overall healthcare quality compared to White patients, is it because Black patients receive lower quality than White patients in the same hospitals (within-hospital effect) and/or because Black patients are more likely to be treated in hospitals that provide lower quality for all patients (between hospital effect)? Our goal was to demonstrate use of the Kitagawa method to decompose the difference in mean healthcare wait times between racial/ethnic subgroups and White Veterans into within- and between-hospital effects.

METHODS: We used 2019-2021 data on 535,550 outpatient orthopedic consults in 140 US Veteran Health Administration hospitals to compare racial/ethnic subgroups of patients to White patients in terms of wait times for consultations. Using a risk-adjusted multivariable model, we calculated the mean adjusted wait times for our 3 racial/ethnic groups: non-Hispanic White (referred to as White Veterans), non-Hispanic Black (referred to as Black Veterans) and Hispanic of any race (referred to as Hispanic Veterans). The Kitagawa approach provided a decomposition of the difference in means into within-hospital vs. between-hospital effects.

RESULTS: Black patients’ mean adjusted wait times were overall 3.4 days longer than White patients, with approximately half (1.7 days) existing within hospitals, and half (1.8 days) existing between hospitals. Hispanic patients mean adjusted wait times were only 0.3 days longer than White patients. However, the decomposition revealed that Hispanic wait times were 1.4 days longer within-hospital and 1.1 days shorter between-hospital effects.

CONCLUSIONS: These analyses illustrate the value of the Kitagawa decomposition, which hopefully will encourage wider use in the analysis of racial/ethnic or other disparities. The estimates of within- and between-hospital effects on the same scale as the outcome is essential to understanding and designing strategies to reduce healthcare disparities.