Table 2.

WOMAC pain and function 2 years after total knee arthroplasty: interaction between education and percent below poverty at census-tract level

Percent below poverty at Census-Tract Level‡	Education	WOMAC Pain at 2 Years*			WOMAC Function at 2 Years**
		Estimate (Standard Error)	Estimated Difference (Standard Error)	P-Value	Estimate (Standard Error)	Estimated Difference (Standard Error)	P-Value
10%	Non-college College/above	83.36 (0.76) 87.10 (0.75)	−3.74 (0.60)	<0.0001	81.01 (0.76) 83.55 (0.75)	−2.54 (0.61)	<0.0001
20%	Non-college College/above	81.23 (0.90) 86.90 (0.97)	−5.66 (1.11)	<0.0001	79.17 (0.90) 83.30 (0.99)	−4.13 (1.13)	0.0003
30%	Non-college College/above	79.11 (1.27) 86.70 (1.37)	−7.58 (1.80)	<0.0001	77.34 (1.27) 83.05 (1.41)	−5.71 (1.82)	0.0017
40%	Non-college College/above	76.99 (1.74) 86.49 (1.85)	−9.50 (2.51)	0.0002	75.51 (1.74) 82.80 (1.90)	−7.30 (2.55)	0.0042
50%	Non-college College/above	74.87 (2.25) 86.29 (2.34)	−11.41 (3.24)	0.0004	73.67 (2.24) 82.55 (2.41)	−8.88 (3.29)	0.0069
60%	Non-college College/above	72.75 (2.77) 86.09 (2.85)	−13.33 (3.97)	0.0008	71.83 (2.76) 82.30 (2.93)	−10.47 (4.03)	0.0094

^*Estimation based on linear mixed-effect model assessing the effect of interaction between education and percent below poverty at census-tract level on WOMAC pain at 2 years after TKA, using the following assumptions: WOMAC pain at baseline=54; age at surgery=67; BMI=30/kg/m²; sex=female; comorbidities=0; race=black

^**Estimation based on linear mixed-effect model assessing the effect of interaction between race and percent of Medicaid coverage at census-tract level on WOMAC function at 2 years after THA, using the following assumptions: WOMAC function at baseline=54; age at surgery=67; BMI=30/kg/m²; sex=female; comorbidities=0; race=black

^‡Percent below poverty at census-tract level was taken as a continuous variable in this model for prediction purposes