title: Converting between high- and low-sensitivity C-reactive protein in the assessment of periprosthetic joint infection.
abstract: Although low-sensitivity CRP (Ls-CRP) is an important tool for evaluating infected orthopedic prostheses, no clinical studies have evaluated whether Hs-CRP is a suitable surrogate for Ls-CRP or other traditional infection biomarkers. The laboratory data of 98 arthroplasty patients with suspected prosthetic infection were reviewed. Hs-CRP was highly correlated with Ls-CRP (R = 0.93). ROC analysis generated 100% sensitivity and 97% specificity for both Hs-CRP and Ls-CRP at optimal cutoffs of 28.6 and 2.6 mg/dL, respectively. Both CRP tests were more accurate than serum erythrocyte sedimentation rate, neutrophil differential, and white blood cell count. Hs-CRP was no different from Ls-CRP after unit conversion, and regression analyses suggested conversion factors that approximated 10. Hs-CRP and Ls-CRP have equivalent utility in the diagnosis of infected joint arthroplasty.
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Milone
authors.affiliation: Department of Orthopaedic Surgery, Mayo Clinic, Rochester MN.
authors.forename: Atul F
authors.initials: AF
authors.lastname: Kamath
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA.
authors.forename: Craig L
authors.initials: CL
authors.lastname: Israelite
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis*; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016459:Prosthesis-Related Infections / Q000097:blood* / Q000175:diagnosis*; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D002097:C-Reactive Protein
keywords: C-reactive protein; biomarkers; periprosthetic infection; total hip arthroplasty; total knee arthroplasty