Probasco William V, Cefalu Charles, Lee Ryan, Lee Danny, Gu Alex, Dasa Vinod
Department of Orthopedic Surgery, George Washington University, 2300 M Street NW, Washington DC, 20037, USA.
Department of Orthopedic Surgery, Louisiana State University Health Sciences Center, 1542 Tulane Avenue, New Orleans, LA, 70112, USA.
J Clin Orthop Trauma. 2020 Oct;11(Suppl 5):S722-S728. doi: 10.1016/j.jcot.2020.05.031. Epub 2020 May 29.
Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are commonly used inflammatory markers utilized to aid in the diagnosis of periprosthetic infection (PJI). Patients with obesity, however, are known to have elevated baseline levels of these inflammatory markers. Therefore, this retrospective study aimed to determine the relationship between elevated ESR and CRP and body mass index (BMI) in patients undergoing total knee arthroplasty (TKA). In doing so, physicians can better determine whether BMI should be taken into account when evaluating the prognostic value of elevated preoperative ESR and CRP levels for risk of PJI in primary TKA patients.
This is a retrospective case series of 181 patients who had undergone primary TKA at a single institution. Patients undergoing primary unilateral TKA were eligible unless they had undergone previous TKA, contralateral knee symptoms, or elevated white blood cell (WBC) count. A linear regression model was utilized to demonstrate the relationship between proportions of patients with elevated biomarker values and categories of BMI. Analysis of variance and independent two-sample t-tests were utilized to assess differences in mean ESR, CRP, and WBC levels between the "healthy patients" and "patients with comorbidities" subgroups within each BMI category.
Eligible patients (n = 181) were stratified by BMI category. Elevated ESR was associated significantly with BMI (ESR: r = 0.89, < 0.001) unlike elevated CRP (r = 0.82, = 0.133) and WBC count (r = .01; = .626). No statistically significant differences in ESR values and WBC count between the "healthy patients" versus "patients with comorbidities" were demonstrated within any BMI category. In patients of normal weight (BMI 20-25 kg/m), "healthy patients" had a statistically significantly higher mean CRP level than "patients with comorbidities" (1.73 mg/L vs. 0.70 mg/L, < 0.001). There were no other statistically significant differences in mean CRP levels by health status.
Caution is advised when utilizing ESR and CRP to diagnose periprosthetic joint infection without considering BMI given that increasing preoperative levels of ESR and CRP are correlated with higher BMI.
红细胞沉降率（ESR）和C反应蛋白（CRP）是常用的炎症标志物，用于辅助诊断假体周围感染（PJI）。然而，已知肥胖患者这些炎症标志物的基线水平会升高。因此，这项回顾性研究旨在确定接受全膝关节置换术（TKA）的患者中ESR和CRP升高与体重指数（BMI）之间的关系。这样，医生在评估术前ESR和CRP水平升高对初次TKA患者发生PJI风险的预后价值时，就能更好地确定是否应考虑BMI。
这是一项对在单一机构接受初次TKA的181例患者的回顾性病例系列研究。接受初次单侧TKA的患者符合条件，除非他们曾接受过TKA、对侧膝关节有症状或白细胞（WBC）计数升高。采用线性回归模型来证明生物标志物值升高的患者比例与BMI类别之间的关系。方差分析和独立两样本t检验用于评估每个BMI类别中“健康患者”和“合并症患者”亚组之间ESR、CRP和WBC平均水平的差异。
符合条件的患者（n = 181）按BMI类别分层。与CRP升高（r = 0.82，P = 0.133）和WBC计数升高（r = 0.01；P = 0.626）不同，ESR升高与BMI显著相关（ESR：r = 0.89，P < 0.001）。在任何BMI类别中，“健康患者”与“合并症患者”之间的ESR值和WBC计数均未显示出统计学上的显著差异。在正常体重（BMI 20 - 25 kg/m²）的患者中，“健康患者”的平均CRP水平在统计学上显著高于“合并症患者”（1.73 mg/L对0.70 mg/L，P < 0.001）。按健康状况划分的平均CRP水平没有其他统计学上的显著差异。
鉴于术前ESR和CRP水平升高与较高BMI相关，在不考虑BMI的情况下使用ESR和CRP诊断假体周围关节感染时应谨慎。
