CORR Insights®: Preoperative Colonization With Staphylococcus Aureus in THA is Associated With Increased Length of Stay

Where Are We Now? Longer length of stay (LOS) and unplanned hospital readmissions adversely affect patients’ experiences, can cause harm, and are expensive. In the past two decades, enhanced recovery pathways that focus on opioid-sparing multimodal analgesia, blood management, early mobilization, and discharge in ways that are believed not to adversely affect safety have become common practice after THA or TKA, and can improve patient care and reduce LOS after elective orthopaedic surgery [7, 12]. These pathways can be implemented without increasing complications, readmissions, morbidity, or mortality [12, 13] This allows for the delivery of high-quality patient care within more restricted healthcare budgets and may improve patient satisfaction, allowing patients to recover in their home environments and achieve independence as early as possible. Both surgery-related and patient-related factors are associated with surgical site infections. One important patient factor linked to surgical site infection in patients undergoing elective orthopaedic procedures and those treated for trauma is Staphylococcus aureus colonization [10, 15]. Because of this, screening and decolonization before surgery have emerged as a strategy to diminish staphylococcal infections [2, 5, 17]. Although various screening and decolonization strategies have been reported, we still lack a consensus about the most appropriate strategy [16]. In the current study, Santana et al. [14] found that S. aureus colonization was associated with problems that were unrelated to infection, specifically increased LOS after THA and 90-day readmission after TKA. This is probably because of unmeasured confounding factors. Patients who screen positive for S. aureus may have other underlying medical problems, which may have driven the findings in this report. However, based on these findings, surgeons should inform patients preoperatively that colonization is a risk factor for a longer LOS and readmission. Second, patients with colonization should be monitored more closely postoperatively because early intervention could avoid subsequent readmission. Where Do We Need To Go? The current study [14] is, to my knowledge, the first study to show a relationship between S. aureus colonization and increased LOS after THA and 90-day readmission after TKA, and so we need to determine whether these findings can be consistently replicated in other centers with other patient populations. As the authors point out, it is unlikely that there is a causal link between colonization and the short-term outcomes of arthroplasty, but colonization with S. aureus may serve as a proxy for patient factors that were not explored in the current study. Future studies might dig deeper to identify those factors and to see whether any of them are modifiable. Recent studies showed that a screening and decolonization regimen reduces nasal colonization with S. aureus prior to arthroplasty [4, 11], but others showed that colonization persists in 20% to 33% of patients, despite decolonization [1, 6]. Whether persistent colonization is a function of nonadherence to the decolonization protocol, the type of carrier (intermittent versus persistent) and level of carriage, or other patient risk factors is not known and needs further study. How Do We Get There? Large institutional databases would allow us to investigate the applicability of the findings of the current study in other centers. Such studies should determine the reasons for prolonged LOS and readmissions. Researchers could then compare them between patients with colonization and those without. Future research should also focus on the underlying patient factors that influence infection, longer LOS, and higher readmission rate after arthroplasty in patients with S. aureus colonization. Risk factors for colonization that are also associated with an increased short-term complication rate after arthroplasty include obesity, gender, age, residency, diabetes, renal insufficiency, and immunosuppression, but there still is disagreement on many of these points. Not all studies have found the same risk factors for colonization, so more data are needed to determine what the risk factors for colonization are exactly [3, 16]. Multiple regression analyses can help researchers determine which independent variables can be used to predict both S. aureus colonization and patient outcomes such as longer LOS and higher readmission rate. Studies need to determine whether the higher risk of complications in patients with colonization is true for all S. aureus carriers or whether some subclasses of carriers have a higher risk than others. The colonization rate in the general population varies worldwide, but three distinct patterns of nasal colonization have been identified in the general population: intermittent carriers (60%), persistent carriers (20%), and noncarriers (20%) [9]. In addition, a distinction can be made between low-level and high-level nasal carriage of S. aureus [8]. Studies looking at the relationship between colonization and infection or short-term complications after arthroplasty should consider these differences and evaluate whether intermittent versus persistent and/or low-level versus high-level carriage are risk factors for these outcomes. A combination of qualitative and quantitative culture results and repeat nasal culture swabs can help to predict S. aureus nasal carriage. We need to ascertain whether persistent colonization is more a function of patients’ nonadherence to recommended decolonization approaches, or whether persistent colonization occurs despite these approaches. Monitoring protocol adherence and screening to test for S. aureus control on the day of surgery would help to determine patient adherence to the protocol at the time of surgery and help to discriminate true persistent carriers versus non-adherence to the decolonization protocol. Linking outcome data to these subgroups could help determine whether colonization is a modifiable or nonmodifiable risk factor for some short-term outcomes after arthroplasty in these subgroups. It could also help to optimize decolonization strategies. If noninfectious complications and S. aureus colonization have underlying risk factors in common, studies should determine whether they are modifiable and can therefore reduce colonization and, most importantly, the complication rate.