To examine if health insurance payer type and income are associated with higher healthcare utilization after primary total knee arthroplasty (TKA).

We used multivariable-adjusted logistic regression to examine the association of the insurance payer type (Medicare, Medicaid, private insurance, self-pay or other), and annual household income (based on zip code; quartiles) with healthcare utilization for index TKA hospitalization, using the 1998–2014 U.S. National Inpatient Sample data. We adjusted for demographics, underlying diagnosis, comorbidity, and hospital characteristics.

The U.S. national cohort consisted of 8,127,282 primary TKA procedures performed between 2002–2014 in the U.S. In multivariable-adjusted analyses, compared to private insurance, Medicaid and other insurance payer status were each associated with significantly higher odds ratio (OR) of hospital charges above the median of 1.11 and 1.07; Medicare, Medicaid, self-pay and other insurance with significantly higher OR of hospital stay>3 days with OR of 1.22, 1.68, 1.43, and 1.32; and Medicare, Medicaid, and other insurance with significantly higher OR of discharge to a rehabilitation facility, with OR of 1.77, 1.40, and 1.14, respectively. Compared to the highest income quartile, patients in the lowest income quartile had a significantly higher OR of 1.34 of hospital charges above the median; income quartiles 1-3 with significantly lower ORs of length of hospital stay>3 days, 0.87, 0.97, and 0.94, and discharge to a rehabilitation facility at 0.73, 0.77, and 0.83, respectively.

Future studies should examine modifiable mediators of differences in healthcare utilization by insurance payer, and income to target them to reduce utilization.