Background Few studies have examined the association of lower income with arthroplasty outcomes. To our knowledge, there is only one study in TKA cohort. This study found no differences in pain and function outcomes 2-years after TKA by income level, but higher gains in lower income group. Thus, knowledge gap exists in this area.
Objectives To assess whether income is associated with patient-reported outcomes (PROs) after primary total knee arthroplasty (TKA).
Methods We used the prospectively collected data from the Mayo Clinic Total Joint Registry to assess the association of income with index knee functional improvement, moderate-severe pain and moderate-severe activity limitation at 2- and 5-year follow-up after primary TKA using multivariable-adjusted logistic regression analyses.
Results There were 7,139 primary TKAs at 2-years and 4,234 at 5-years. In multivariable-adjusted analyses, at 2-year follow-up, compared to income >$45K, lower income of ≤$35K and >$35-45K were associated: (1) significantly with moderate-severe pain with odds ratio (OR) 0.61 [95% confidence interval (95% CI): 0.40, 0.94] (p=0.02) and 0.68 [95% CI: 0.49, 0.94] (p=0.02); and (2) trend towards significance for moderate-severe activity limitation with OR 0.78 [95% CI: 0.60, 1.02] (p=0.07) and no significant association with OR, 0.96 [95% CI: 0.78, 1.20] (p=0.75), respectively. At 5-years, odds were not statistically significantly different by income, although numerically favored lowering income. In multivariable-adjusted analyses, overall improvement in knee function was rated as ‘better’ slightly more often at 2-years by patients with income in the ≤$35K compared to patients with income >$45K, with an OR 1.9 [95% CI: 1.0, 3.6] (p=0.06).
Conclusions We found that patients with lower income had better pain outcomes compared to patients with higher income. There was more improvement in knee function, and trend towards less overall activity limitation after primary TKA in lower income patients, compared to higher income. Insights into mediators of these relationships need to be investigated to understand how income influences outcomes after TKA.
Disclosure of Interest None Declared