rss
Ann Rheum Dis 2005;64:612-615 doi:10.1136/ard.2004.027268
  • Extended report

Analysis for crystals in synovial fluid: training of the analysts results in high consistency

  1. B Lumbreras1,
  2. E Pascual2,
  3. J Frasquet1,
  4. J González-Salinas1,
  5. E Rodríguez1,
  6. I Hernández-Aguado3
  1. 1Department of Clinical Analysis, Hospital General Universitario de Alicante, Alicante, Spain
  2. 2Rheumatology Section, Hospital General Universitario de Alicante and Universidad Miguel Hernández, Alicante
  3. 3Department of Public Health, Universidad Miguel Hernández, San Juan de Alicante
  1. Correspondence to:
    Professor Eliseo Pascual
    Sección de Reumatología, Hospital General Universitario de Alicante, Maestro Alonso 109, 03010 Alicante, Spain; pascual_eligva.es
  • Accepted 12 August 2004

Abstract

Background: Identification of monosodium urate (MSU) and calcium pyrophosphate dehydrate (CPPD) crystals in synovial fluid samples is diagnostic of gout and CPPD crystal related arthropathy. Various studies have shown poor consistency in results of crystal analysis.

Objective: To determine whether training of the analysts increases the consistency.

Methods: An expert rheumatologist gave a course on crystal detection and identification. The four trained observers then blindly and independently examined synovial fluid samples previously classified by the expert which had been obtained from patients with both crystal arthropathies and other non-crystal related inflammatory joint conditions.

Results: 194 observations were made on 64 synovial fluid samples: 96 without crystals (49.4%), 55 with CPPD crystal (28.4%), and 43 with MSU crystals (22.2%). For crystal detection (presence or absence of crystals), sensitivity was 95.9% and specificity 86.5%. For identification of MSU crystals, sensitivity was 95.3% and specificity 97.2%. For identification of CPPD crystals, sensitivity was 92.7% and specificity 92.1%. The κ index of agreement with the reference standard between the observers was 0.84 for any crystal detection, 0.93 for MSU crystal sample identification, and 0.79 for CPPD crystal sample identification.

Conclusions: For trained observers, the detection and identification of crystals in synovial fluid is a consistent procedure.

Footnotes

    This Article

    1. Abstract
    2. Full text
    3. PDF

    Responses

    1. Submit a response
    2. No responses published

    Register for free content

    The full back archive is now available for all BMJ Journals. Institutional subscribers may access the entire archive as part of their subscription. Personal subscribers will also have access to all content when logged in. Non-subscribers who register have free access to all articles published before 2006 right back to volume 1 issue 1. Register here to access the free archive of all BMJ Journals.

    Don't forget to sign up for content alerts so you keep up to date with all the articles as they are published.