Distinguishing lyme from septic knee monoarthritis in lyme disease-endemic areas

Julia K. Deanehan, Amir A. Kimia, Sharman P.Tan Tanny, Matthew D. Milewski, Paul G. Talusan, Brian G. Smith, Lise E. Nigrovic

Research output: Contribution to journalArticle

Abstract

Objective: Because Lyme and septic arthritis may present similarly, we sought to identify children with knee monoarthritis at low risk for septic arthritis who may not require arthrocentesis. Methods: We performed a retrospective study of children with knee monoarthritis presenting to 1 of 2 pediatric centers, both located in Lyme disease-endemic areas. Septic arthritis was defined by a positive result on synovial fluid culture or synovial fluid pleocytosis with a positive blood culture result. Lyme arthritis was defined as a positive Lyme serologic result or physician-documented erythema migrans rash. All other children were considered to have other inflammatory arthritis. A clinical prediction model was derived by using recursive partitioning to identify children at low risk for septic arthritis, and the model was then externally validated. Results: We identified 673 patients with knee monoarthritis; 19 (3%) had septic arthritis, 341 (51%) had Lyme arthritis, and 313 (46%) had other inflammatory arthritis. The following predictors of knee septic arthritis were identified: peripheral blood absolute neutrophil count ≥10 × 103 cells per mm3 and an erythrocyte sedimentation rate ≥40 mm/hour. In the validation population, no child with a absolute neutrophil count <10 × 103 cells per mm 3 and an erythrocyte sedimentation rate <40 mm/hour had septic arthritis (sensitivity: 6 of 6 [100%], 95% confidence interval [CI]: 54-100; specificity: 87 of 160 [54%], 95% CI: 46-62). Overall, none of the 19 children with septic arthritis were classified as low risk (10%, 95% CI: 0-17). Conclusions: Laboratory criteria can be used to identify children with knee monoarthritis at low risk for septic arthritis who may not require diagnostic arthrocentesis.

Original languageEnglish (US)
Pages (from-to)e695-e701
JournalPediatrics
Volume131
Issue number3
DOIs
StatePublished - Mar 2013
Externally publishedYes

Keywords

  • Arthrocentesis
  • Clinical prediction rule
  • Knee arthritis
  • Lyme disease
  • Septic arthritis

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health

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    Deanehan, J. K., Kimia, A. A., Tanny, S. P. T., Milewski, M. D., Talusan, P. G., Smith, B. G., & Nigrovic, L. E. (2013). Distinguishing lyme from septic knee monoarthritis in lyme disease-endemic areas. Pediatrics, 131(3), e695-e701. https://doi.org/10.1542/peds.2012-2531