New Study Demonstrates the Value of Using the D-Dimer Blood Test to Detect PJIs
Measurement of plasma D-dimer levels – a test more commonly used to detect blood-clotting disorders – can provide useful information when making the difficult diagnosis of periprosthetic joint infection (PJI), according to a study published online ahead of print by The Journal of Bone & Joint Surgery.
Plasma D-dimer measurement has “comparable diagnostic accuracy” to other commonly used tests for identifying PJI, and in some situations outperforms the standard tests, report Javad Parvizi, MD, FRCS, and colleagues from The Rothman Orthopaedic Institute at Thomas Jefferson University, Philadelphia.
Periprosthetic joint infection is a devastating complication of failed total hip or knee replacement and is one of the leading causes of implant failure. Diagnosis of PJI can be “extremely challenging,” according to the authors, as no single test has “absolute accuracy” in determining whether PJI is present.
Two common markers of inflammation – C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) – are recommended as screening tests for suspected PJI. However, both have limitations, including a high rate of false-negative results when PJI is present.
Plasma D-dimer is a potentially useful marker of infection that has been validated for use in diagnosing PJI. However, some studies have raised concerns about the diagnostic performance of D-dimer testing for PJI, and its true accuracy remains unknown.
Assessing the Accuracy of 4 Tests
In the new study, Dr. Parvizi and colleagues compared plasma D-dimer and other tests in the diagnosis of PJI. Over a 4-year period, the study authors prospectively enrolled 502 patients undergoing revision knee or hip arthroplasty regardless of their surgical indication. Immediately before surgery, all patients had blood drawn, from which the levels of D-dimer, CRP, and ESR, and fibrinogen were measured.
After application of the 2018 International Consensus Meeting definition of PJI, 23% of patients were found to have PJI. The 4 tests had “comparable accuracy” for the diagnosis of PJI.
- Sensitivity was 81.3% for D-dimer, 90.4% for CRP, 73.9% for ESR, and 74.7% for fibrinogen
- Specificity was 81.7% for D-dimer, 70.0% for CRP, 85.2% for ESR, and 75.4% for fibrinogen
With all 4 measures, values were higher for patients who were shown to have PJI.
However, in certain patient subgroups, D-dimer offered a diagnostic advantage. In a sub-analysis that excluded patients with certain health conditions associated with inflammation, the D-dimer test outperformed ESR, fibrinogen, and CRP in recognizing the presence of PJI. D-dimer also performed best in detecting PJI caused by slow-growing “indolent” organisms, with higher values for both sensitivity and specificity.
All 4 tests had better diagnostic performance in patients with suspected PJI in the knee, as compared with PJI in the hip.
Useful Adjunct for Screening
This is the largest prospective study evaluating the performance of different laboratory tests for suspected PJI. The findings support the value of D-dimer testing to make this often-difficult diagnosis. The authors discuss possible limitations of previous studies that questioned the diagnostic value of D-dimer testing.
“We found that plasma D-dimer was noninferior to serum CRP and ESR in the diagnosis of PJI and may be a useful adjunct when screening patients undergoing revision total joint arthroplasty,” Dr. Parvizi and colleagues concluded.
They highlighted the need for further studies and noted that no universal diagnostic cutoff point can be determined, due to known variations in D-dimer measurement.
Tarabichi S, Goh GS, Baker CM, Chisari E, Shahi A, Parvizi J. Plasma d-dimer is noninferior to serum c-reactive protein in the diagnosis of periprosthetic joint infection. J Bone Joint Surg Am. 2023 Feb 9. doi: 10.2106/JBJS.22.00784. Online ahead of print.