Table 5.

Mediation analysis of ADI on associations observed between Black or White race with LOS 3 or more days and nonhome discharge in patients who underwent THA

Association	Estimate (95% CI)	p value	% mediation
LOS > 3 days
Mediation (indirect)	-0.043 (-0.063 to -0.026)	< 0.001	37%
Direct	-0.075 (-0.13 to -0.024)	0.004	64%
Total	-0.117 (-0.17 to -0.065)	< 0.001	100%
Nonhome discharge
Mediator (indirect)	0.041 (0.024 to 0.059)	< 0.001	40%
Direct	0.060 (0.016 to 0.109)	0.004	60%
Total	0.101 (0.053 to 0.149)	< 0.001	100%

Mediation analysis explored the degree to which the observed relationship between race (independent variable) and LOS of 3 or more days/nonhome discharge (dependent variables) was completely or partially explained by ADI (mediator). The estimates from mediation analysis represent the proportion of the total effect on the dependent variables that may be attributed to the independent variable and the mediator. The mediation (indirect) effect divided by the total effect was used to calculate the percent mediation for each outcome. For example, the mediation effect of ADI on the effect of race on LOS of 3 days or more was -0.043, and the total effect of race on LOS of 3 days or more was -0.117. The percentage of the total effect of race on LOS of 3 days or more that is mediated by ADI was calculated as -0.043/-0.117 = 0.37 or 37%.