Are Patients Who Undergo THA for Infection at Higher Risk for 30-day Complications?
Authors: Boniello Anthony J. , Lieber Alexander M. , Courtney P. Maxwell 
Published: May 2019

Abstract

Background
Value-based payment models, such as bundled payments, continue to become more widely adopted for total joint arthroplasty. However, concerns exist regarding the lack of risk adjustment in these payment and quality reporting models for THA. Providers who care for patients with more complicated problems may be financially incentivized to screen out such patients if reimbursement models fail to account for increased time and resources needed to care for these more complex patients.

Questions/purposes
(1) Are patients who undergo revision THA for infectious causes at greater adjusted risk of 30-day short-term major complications, return to the operating room, readmission, and mortality compared with patients undergoing aseptic revision? (2) What are other independent factors associated with the risk of 30-day major complications, readmission, and mortality in this patient population?

Methods
We queried the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database for all patients undergoing revision THA from 2012 to 2015. The NSQIP database allows for the analysis of 30-day surgical outcomes, including postoperative complications, return to the operating room, readmission, and mortality of patients from approximately 400 participating institutions. The NSQIP was selected over other larger databases, such as the National Impatient Sample (NIS), because the NSQIP includes readmission data and 30-day complications rates that were relevant to our study. Patients undergoing aseptic revision THA and those undergoing revision THA with a diagnosis of periprosthetic joint infection were identified. We identified 8973 patients who underwent revision THA and excluded six patients due to a diagnosis of malignancy leaving 8967 patients; 726 (8%) of these were due to infection. Demographic variables, medical comorbidities, and 30-day major complications, hospital readmissions, reoperations, and mortality were compared among patients undergoing aseptic and infected revision THA. A major complication was defined as myocardial infarction, postoperative mortality, sepsis, septic shock, and stroke. A multivariate logistic regression analysis was then performed to identify factors independently associated with the primary outcome of 30-day hospital readmission, and secondary endpoints of 30-day major complications, return to operating room, and mortality.

Results
Controlling for medical comorbidities and demographic factors, the patients who underwent THA for infection were more likely to experience a major complication (odds ratio [OR], 4.637; 95% confidence interval [CI], 2.850–7.544; p < 0.001) within 30 days of surgery and more likely to return to the operating room (OR = 1.548; 95% CI, 1.062–2.255; p = 0.023). However, there were no greater odds of 30-day readmission (OR, 1.354; 95% CI, 0.975–1.880; p = 0.070) or 30-day mortality (OR, 0.661; 95% CI, 0.218–2.003; p = 0.465). Preoperative malnutrition was associated with an increased risk of return to the operating room (OR, 1.561; 95% CI, 1.152-2.115; p = 0.004), 30-day readmission (OR, 1.695; 95% CI, 1.314–2.186; p < 0.001), and 30-day mortality (OR, 7.240; 95% CI, 2.936–17.851; p < 0.001).

Conclusions
Patients undergoing revision THA for infection undergo reoperation and experience major complications more frequently in a 30-day episode of care than patients undergoing aseptic revision THA. Without risk adjustment to existing alternative payment and quality reporting models, providers may experience a disincentive to care for patients with infected THAs, who may face difficulties with access to care.

Level of Evidence
Level III, therapeutic study.