Autoantibody detection with indirect immunofluorescence on HEp-2 cells: Starting serum dilutions for systemic rheumatic diseases

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• 作者：Delia Almeida Gonzá ; lez^a ; Antonio Cabrera de Le&#xf3 ; n^b ; ^c ; ^{acableo@gobiernodecanarias.org"" rel=""nofollow} ; ^{delia38204@yahoo.com"" rel=""nofollow} ; Alfredo Roces Varela^d ; Miriam Garcí ; a Garcí ; a^d ; Marta de Sequera Rahola^e ; Marí ; a del Cristo Rodrí ; guez Pé ; rez^b ; Ana Gonzá ; lez Herná ; ndez^b ; Marí ; a José ; Falc&#xf3 ; n Falc&#xf3 ; n^d ; Buenaventura Brito Dí ; az^b
• 关键词：Antinuclear antibodies ; Indirect immunofluorescence technique ; Anti-ENA antibodies ; Anti-DNA antibodies ; Costs
• 刊名：Immunology Letters
• 出版年：2011
• 出版时间：30 October 2011
• 年：2011
• 卷：140
• 期：1-2
• 页码：30-35
• 全文大小：250 K

文摘

Antinuclear antibodies (ANA) are determined, among other reasons, to identify samples which need a second test to detect the associated specificities. Our aim was to evaluate the clinical and economic impact generated by using an initial dilution for ANA of 1:160. We analyzed all samples for which ANA, anti-ENA and anti-dsDNA were requested over a 1-year period. ANA were detected by indirect immunofluorescence. Anti-ENA were analyzed with a combination of techniques. Anti-dsDNA were detected by radioimmunoassay. Cost analysis was performed by calculating the difference between two cut-offs (ANA 1:40 and 1:160). A total of 13,233 samples were processed for ANA, of which 59.9 % were positive with the 1:40 cut-off and 39.2 % with the 1:160 cut-off. At ANA titer 1:40, 0.2 % of the samples were anti-ENA-positive and 2.2 % were anti-dsDNA positive. Only ANA dilutions of 1:160 and higher showed significantly increased positive predictive value for anti-ENA (1.5 versus 0.2, p = 0.029) and anti-dsDNA (8.3 versus 2.2, p < 0.001) compared to the 1:40 titer. With the 1:160 cut-off, 16.6 % fewer ANA tests, 41.8 % fewer anti-ENA determinations and 36.4 % fewer anti-dsDNA tests would have been needed. The average saving was 0.87 cost-units per sample (1 unit = 2.06 euro). We conclude that setting the starting dilution for ANA at 1:160 avoids unnecessary studies, increases the positive predictive values of ANA for anti-ENA and anti-dsDNA, and generates clinical and economic benefits.