Association between socioeconomic status and pain, function and pain catastrophizing at presentation for total knee arthroplasty

BACKGROUND: Patients with higher socioeconomic status (SES) are shown to have better total knee arthroplasty (TKA) outcomes compared to those with lower SES. The relationship between SES and factors that influence TKA use is understudied. We examined the association between SES and pain, function and pain catastrophizing at presentation for TKA. METHODS: In patients undergoing TKA at an academic center, we obtained preoperative pain and functional status (WOMAC Index 0–100, 100 worst), pain catastrophizing (PCS, ≥16 high), and mental health (MHI-5, <68 poor). We described individual-level SES using education as a proxy, and area-level SES using a validated composite index linking geocoded addresses to U.S. Census data. We measured associations between these indicators and pain, function and pain catastrophizing, adjusting for age, sex and BMI. RESULTS: Among 316 patients, mean age was 65.9 (SD 8.7), 59% were female, and 88% were Caucasian; 17% achieved less than college education and 62% were college graduates. The median area SES index score was 59 (U.S. median 51). Bivariable analyses demonstrated associations between higher individual- and area-level SES and lower pain, higher function and less pain catastrophizing (all p<0.05). Adjusted analyses demonstrated statistically significant associations between higher individual- and area-level SES and better function and less pain. CONCLUSION: In this cohort, patients with higher individual- and area-level SES had lower pain and higher function at the time of TKA than lower SES patients. Further research is needed to assess what constitutes appropriate levels of pain and function to undergo TKA in these higher SES groups. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12891-015-0475-8) contains supplementary material, which is available to authorized users.