Paper of the Week: Socioeconomic Status May Not Be a Risk Factor for Periprosthetic Joint Infection

Graham J. DeKeyser, MD, Mike B. Anderson, MS, Huong D. Meeks, PhD, Christopher E. Pelt, MD, Christopher L. Peters, MD, Jeremy M. Gililland, MD

Reference for summarized article J Arthroplasty. 2020 Mar 5. pii: S0883-5403(20)30219-9.
doi: 10.1016/j.arth.2020.02.058

Summary by Amer Haffar, BS

Periprosthetic joint infection (PJI) is a devastating complication after Total Joint Arthroplasty (TJA). The cost to treat PJI following Total Knee Arthroplasty (TKA) is estimated to be between $44,000 and $270,000 per patient.1 With the increased utilization of total arthroplasty procedures in the United States, the total cost to treat PJI is expected to rise to $1.62 billion by the year 2020.2 The 5-year mortality rate associated with PJI is greater than that of breast cancer, melanoma, and Hodgkin’s lymphoma.3 Among Medicare patients, the 5-year survival rate after hip or knee PJI is 67% and 71%, respectively. These survival rates are lower than those associated with either breast cancer or prostate cancer.4 Previous studies demonstrate that socioeconomic status (SES) plays an important role in outcomes after TJA.5,6 To date, however, no large cohort study has investigated the effect of SES variables on rates of acquiring PJI.7 As such, the purpose of the study by DeKeyser et al., was to determine how SES variables, known risk factors, and family genealogy influence the rate of PJI following TJA using a statewide database.

This population-based retrospective cohort study of patients who underwent primary TKA or total hip arthroplasty (THA) over an 18 year period (1996-2013) included 85,332 patients. From this cohort, 9,854 patients were excluded due to age<18, missing information, history of PJI prior to index procedure, or no evidence of 2 year follow up. In the final cohort, 2,282 (3%) of patients developed PJI. After making covariate adjustments, Medicaid patients (relative risk 1.39, 95% C.I 1.07-1.81, p<0.01), 1st degree relatives of patients who developed PJI (Hazard Ratio [HR] 1.66, 95% CI 1.23-2.24, P=0.01), and those with either a 1st degree and/or 2nd degree relative who developed PJI (HR 1.39, 95% C.I 1.09-1.77, p=0.007) were at greater risk for PJI respectively. Education level and median household income had no effect on risk of PJI. The finding that patients on Medicaid have a higher risk for developing PJI could have been confounded by several factors, including: modifications to the surgical technique to drive down costs (faster operative time, using less expensive implants, more autonomy to trainees), Medicaid patients being driven to less skilled surgeons due to market competition, or less buy-in with regards to rehabilitation and postoperative self-care. Finally, the methodology of the study did not allow for determining whether the familial risk of PJI can be attributed to genetics, socioeconomics, or a combination of both.

In conclusion, Medicaid patients, and those with family history of PJI after TJA are at greater risk of developing PJI. Medicaid insurance status should be assessed as an independent risk factor. Neighborhood household income and education level do not confer significant increased risk of developing PJI following TKA.

References:

1. Kapadia BH, McElroy MJ, Issa K, Johnson AJ, Bozic KJ, Mont MA. The economic impact of periprosthetic infections following total knee arthroplasty at a specialized tertiary-care center. J Arthroplasty. 2014. doi:10.1016/j.arth.2013.09.017
2. Kurtz SM, Lau E, Watson H, Schmier JK, Parvizi J. Economic burden of periprosthetic joint infection in the united states. J Arthroplasty. 2012. doi:10.1016/j.arth.2012.02.022
3. Zmistowski B, Karam JA, Durinka JB, Casper DS, Parvizi J. Periprosthetic joint infection increases the risk of one-year mortality. J Bone Jt Surg – Ser A. 2013. doi:10.2106/JBJS.L.00789
4. Kurtz SM, Lau EC, Son MS, Chang ET, Zimmerli W, Parvizi J. Are We Winning or Losing the Battle With Periprosthetic Joint Infection: Trends in Periprosthetic Joint Infection and Mortality Risk for the Medicare Population. J Arthroplasty. 2018. doi:10.1016/j.arth.2018.05.042
5. Barrack RL, Ruh EL, Chen J, et al. Impact of socioeconomic factors on outcome of total knee arthroplasty knee. In: Clinical Orthopaedics and Related Research. ; 2014. doi:10.1007/s11999-013-3002-y
6. Allen Butler R, Rosenzweig S, Myers L, Barrack RL. The frank stinchfield award: The impact of socioeconomic factors on outcome after THA: A prospective, randomized study. In: Clinical Orthopaedics and Related Research. ; 2011. doi:10.1007/s11999-010-1519-x
7. DeKeyser GJ, Anderson MB, Meeks HD, Pelt CE, Peters CL, Gililland JM. Socioeconomic Status May Not Be a Risk Factor for Periprosthetic Joint Infection. J Arthroplasty. 2020. doi:10.1016/j.arth.2020.02.058