The leukocyte esterase strip test yielded a high specificity, positive predictive value, negative predictive value and moderate sensitivity when matched to the current Musculoskeletal Infection Society criteria, demonstrating an accurate, effective marker of periprosthetic joint infection, according to study results.
Researchers prospectively evaluated the presence of leukocyte esterase in synovial joint aspirates from hips and knees from May 2009 to May 2013 in a cohort comprising 189 hip and knee aspirations. A centrifuge was used on bloody aspirates to precipitate red blood cells and obtain clear synovial fluid. The presence of leukocyte esterase was detected using a standard chemical test strip, and ++ and +/++ used as two positive strip result scenarios calculated sensitivity, specificity, positive predictive value and negative predictive value of the leukocyte esterase strip test.
Overall, the researchers obtained synovial fluid from 221 joints that underwent revision total hip or total knee arthroplasty for either mechanical failure or periprosthetic infection. Results showed the leukocyte esterase test with a threshold of +/++ had a sensitivity of 79.2%, a specificity of 80.8%, a positive predictive value of 61.8% and a negative predictive value of 90.1%.
When ++ was used as a positive leukocyte esterase result, the sensitivity was 66%, specificity was 97.1%, positive predictive value was 89.7% and negative predictive value was 88%, according to the researchers.
Disclosure: See the study for a full list of all authors’ relevant financial disclosures.