Serum Screening

Six Level I studies evaluating the ESR,^{11, 21, 37, 48, 93, 96} six Level I studies evaluating the CRP,^{11, 21, 31, 37, 93, 96} and two Level I studies evaluating the combined use of ESR and CRP ^{37, 96} were used for analysis. 

The use of screening inflammatory markers (ESR and CRP) is the starting point in the work-up investigations for the diagnosis or exclusion of periprosthetic joint infection.  Our systematic review of the literature found strong evidence for using both ESR and CRP testing. We recommend use of this combination of tests to “rule out” infection.

The combined use of ESR and CRP is a very good “rule out” test. When both the ESR and CRP are negative, periprosthetic infection is unlikely (negative likelihood ratio 0 – 0.06). When both tests are positive, periprosthetic infection must be considered (positive likelihood ratio 4.3 – 12.1), and this result warrants further investigations.  However, the clinician also needs to be aware of other inflammatory conditions such as rheumatoid arthritis, neoplasms, coronary artery disease, polymyalgia rheumatica, inflammatory bowel disease, etc. that can lead to elevation of inflammatory markers. The use of either test alone is less reliable for either ‘ruling out’ or ‘ruling in’ infection than when both tests are combined.  A negative ESR is better at ‘ruling out’ infection than a positive result is for ‘ruling in’ infection (better negative likelihood ratio than positive likelihood ratio).  Similarly, the CRP is a better test for ‘ruling out’ infection, but somewhat better than the ESR at ‘ruling in’ infection.   

The evidence strongly supports obtaining an ESR and CRP in all patients being assessed for periprosthetic infection.