title: Measurement of anti-DFS70 antibodies in patients with ANA-associated autoimmune rheumatic diseases suspicion is cost-effective.
abstract: The presence of antinuclear antibodies (ANA) is associated with a wide range of ANA-associated autoimmune rheumatic diseases (AARD). The most commonly method used for the detection of ANA is indirect immunofluorescence (IIF) on HEp-2 cells. This method is very sensitive but unspecific. As a consequence, ANA testing on HEp-2 substrates outside a proper clinical specialist framework may lead to inappropriate referrals to tertiary care specialists and, worst case inappropriate and potentially toxic therapy for the patient. Among ANA, isolated anti-DFS70 antibodies represent a potentially important biomarker that can be clinically used to discriminate AARD from non-AARD patients in ANA IIF positive individuals. Therefore, their presence may avoid unnecessary follow-up testing and referrals. In our study, we investigated if the implementation of a new ANA workup algorithm allowing for the identification of anti-DFS70 antibodies is cost-effective through the reduction of both unnecessary follow-up testing and outpatient clinic visits generated by the clinical suspicion of a potential AARD. None of the 181 patients included with a positive monospecific anti-DFS70 antibody result developed SARD during the follow-up period of 10 years. The reduction in number of tests after ANA and anti-DFS70 positive results was significant for anti-ENA (230 vs. 114 tests; p < 0.001) and anti-dsDNA antibodies (448 vs. 114 tests; p < 0.001). In addition, the outpatient clinic visits decreased by 70 % (p < 0.001). In total, the adoption of the new algorithm including anti-DFS70 antibody testing resulted in a cost saving of 60869.53 € for this pilot study. In conclusion, the use of anti-DFS70 antibodies was clearly cost-efficient in our setting.
authors.affiliation: Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain.
authors.forename: Simón
authors.initials: S
authors.lastname: Gundín
authors.affiliation: Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Irure-Ventura
authors.affiliation: Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Asensio
authors.affiliation: Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Ramos
authors.affiliation: Inova Diagnostics, San Diego, CA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Mahler
authors.affiliation: Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain.
authors.forename: Victor
authors.initials: V
authors.lastname: Martínez-Taboada
authors.affiliation: Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain. mlopezhoyos@humv.es.
authors.forename: Marcos
authors.identifier: http://orcid.org/0000-0003-0562-427X
authors.initials: M
authors.lastname: López-Hoyos
keywords: ANA-associated autoimmune rheumatic diseases; Antinuclear antibodies; Cost-effectiveness; DFS-70; Indirect immunofluorescence