Converting between high- and low-sensitivity C-reactive protein in the assessment of periprosthetic joint infection

J Arthroplasty. 2014 Apr;29(4):685-9. doi: 10.1016/j.arth.2013.09.015. Epub 2013 Oct 18.

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.

Keywords: C-reactive protein; biomarkers; periprosthetic infection; total hip arthroplasty; total knee arthroplasty.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Blood Sedimentation
  • C-Reactive Protein / analysis*
  • Female
  • Humans
  • Leukocyte Count
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Prosthesis-Related Infections / blood*
  • Prosthesis-Related Infections / diagnosis*
  • ROC Curve
  • Sensitivity and Specificity

Substances

  • C-Reactive Protein