Preoperative Glycemic Markers and the Risk of Periprosthetic Joint Infection After Total Hip Arthroplasty

Commentary In their study, Wier et al. intended to identify preoperative blood glucose level thresholds that were associated with an increased risk of periprosthetic joint infection (PJI) after total hip arthroplasty (THA). The main findings of the study were an increased risk of PJI in patients undergoing THA who had diabetes and a preoperative blood glucose level of >277 mg/dL and in patients who did not have diabetes but had a preoperative blood glucose level of >193 mg/dL. Previous literature has shown a clear dose-effect relationship (best, <130 mg/dL; worst, 180 to 250 mg/dL) between glucose control and infection after colorectal and bariatric surgery1. However, within arthroplasty, the influence of perioperative hyperglycemia on PJI remains controversial and with no consensus with regard to the optimal cutoff for hemoglobin A1c or serum glucose levels. This may be attributed to the timing of the blood glucose measurement, which included collection in the days or weeks prior to the surgical procedure and collection in the postoperative period2. The literature has shown varied results with regard to the association between blood glucose levels and infection after total joint arthroplasty (TJA). Several studies have found increased risks of surgical site infection in patients with diabetes presenting with blood glucose levels of >200 mg/dL. However, various other studies in the literature have shown no independent association between preoperative blood glucose levels and PJI after adjusting for confounding variables. These differences can be ascribed to the heterogeneity of the variables controlled for, number of patients examined, timing of the preoperative serum glucose levels, levels of evidence of the studies, and nature of the baseline populations studied, as well as modeling that was driven by a relatively small number of events3,4. Furthermore, the findings of the aforementioned studies should be interpreted in the context of additional patient risk factors for PJI, such as obesity, malnutrition, and rheumatologic disease. It is important to recognize that PJI is one of many complications resulting from hyperglycemia following arthroplasty, which includes bacteremia, pneumonia, urinary tract infections, surgical complications, and mortality5. Key questions arise from the analysis of this study regarding glycemic management, and further studies to investigate glycemic management are required. These include whether all candidates for joint arthroplasty should undergo hemoglobin A1c and glucose testing regardless of a prior diagnosis of diabetes, what the target values before arthroplasty should be, and whether a surgical procedure should be delayed for patients with abnormal values. The clinical implications of these findings can be applied to determine relevant serum glucose values that may allow surgeons to identify an increased PJI risk on the day of the surgical procedure. However, the decision to proceed with a surgical procedure in the setting of an elevated preoperative blood glucose value on the day of the surgical procedure is currently not guided by strong evidence. A "wrong" threshold could immensely impact TJA outcomes, and, although patients should be optimized preoperatively, the use of a single marker should not dictate care entirely. A recent study strongly recommended universal glycemic screening for all patients undergoing elective arthroplasty based on their finding that 40.9% of patients in their study had clinical diabetes that went undiagnosed. Screening may have the potential to avoid short-term and long-term complications6. This is reflected by the Fracture-Related Infection Group, which supported that all patients should be screened for glycemic control7. This may avoid the need to study the effect of a diagnosis of diabetes as a proxy for hyperglycemia and to examine blood glucose itself, as was done in the current study by Wier et al. Future research is needed to determine additional preoperative glycemic markers, including fructosamine, that may better predict the risk of PJI, the appropriate targets for preoperative glycemic markers in patients undergoing arthroplasty, the role of tight glucose control on complications of arthroplasty, and the role of universal glycemic screening before arthroplasty. Fructosamine has been shown to better reflect glycemic control, have greater predictive power for adverse events, and respond more quickly to treatment compared with hemoglobin A1c8. The findings of the current study accentuate the importance of preoperative optimization of glucose levels in both patients with and without diabetes as a means to mitigate complications following arthroplasty. The identification and appropriate management of high-risk patients should guide future investigations. Additionally, a multidisciplinary approach that involves surgeons, medical providers, and patients and considers patient risk factors beyond blood glucose levels is essential to maximizing patient care and subsequent outcomes.