PoM No 11, 2013

Publication of the Month

November 11/13: Recommendations for ANA measurement

 

Key messages:

  • The detection of ANA, anti-ENA and anti-dsDNA should be done as similar as possible in all labs worldwide. These recommendations are based on the agreement of a huge group of experts from Europe, US and Canada and can enable harmonisation of local algorithms.
  • “Autoantibodies to cellular antigens” is suggested as a new more appropriate terminology for ANA.

 

Agmon-Levin N, Damoiseaux J, Kallenberg C, Sack U, Witte T, Herold M, Bossuyt Xet al.
International recommendations for the assessment of autoantibodies to cellular antigens referred to as anti-nuclear antibodies.
Ann Rheum Dis 2013; 10.1136/annrheumdis-2013-203863

 

Background: A European-wide questionnaire has shown that the routine use of tests for the detection of ANA and anti-dsDNA varies widely. Recommendations have been developed accordingly, involving expert teams from 15 European countries and from USA and Canada.

 

Summary: The “European autoimmunity standardization initiative” together with the “International Union of Immunologic Societies/World Health Organization/Arthritis Foundation/Centers for Disease Control and Prevention autoantibody standardising committee” (IUIS/WHO/AF/CDC) agreed on 25 recommendations:

1-13 are on ANA screening at the first level of diagnosis. Indirect immunofluorescence (IIF) on HEp-2 cells is the reference method. However, the limitations of IIF were acknowledged. Alternative methods such as automated solid phase assays are included in the recommendations as long as the platform being used is clearly specified and the result is not referred to as “ANA test” or “ANA screen”, which are typically associated with ANA testing by IIF.

14-18 relate to testing of anti-dsDNA antibodies. The appropriate method for determination of anti-dsDNA is still a matter of debate. Farr and CLIFT have the highest specificity but both methods have substantial drawbacks which can be overcome by alternative methods such as enzyme immunoassays (EIA). It is recommended that positive results obtained by alternative methods should be confirmed by CLIFT or Farr assay. If discrepancy is observed both results should be reported. A follow-up with the same quantitative methods is recommended.

19-23 are recommendations on detection of specific antibodies. Antigen specificity cannot be deduced from the IIF pattern alone. In addition, the coexistence of negative ANA by IIF and seropositivity for specific antibodies by solid phase assay is not rare, i.e., anti-Jo-1, anti-ribosomal P or anti-SSA/Ro. In the latter case, specifying the antigen used in evaluation of both anti-Ro52/TRIM21 and anti-Ro60 should be considered.

24-25 are recommendations for verifying the recommended cut-offs.

 

Comment: Most recommendations got a very high Delphi score of above 9.0 which mirrors the high utility of these recommendations worldwide. Lowest degree of agreement with Delphi scores of 7.6 and 8.0, respectively, was found for recommendations 25 (cut-off determination in each laboratory) and 15 (CLIFT and Farr as references methods for the determination of anti-dsDNA).

 

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.