title: Performance of anti-C1q, antinucleosome, and anti-dsDNA antibodies for detecting concurrent disease activity of systemic lupus erythematosus.
abstract: The objective of this study is to evaluate the specificity and sensitivity of antinucleosome, anti-C1q, and anti-dsDNA antibodies for detecting concurrent disease activity in systemic lupus erythematosus (SLE). Consecutive patients were recruited for serological testing of anti-dsDNA, IgG-antinucleosome, IgG-anti-C1q, and complement levels. SLE disease activity was assessed by SLEDAI and physician's global assessment (PGA). The levels of these antibodies, complements, and disease activity scores were correlated. The specificity and sensitivity of these antibodies in detecting SLE activity was determined. We recruited 245 SLE patients (95% women, age 40.6 ± 12.2 years). The prevalence of positive anti-dsDNA, antinucleosome and anti-C1q antibodies was 55%, 44%, and 21%, respectively. All 3 antibodies correlated significantly with SLEDAI and PGA scores but were correlated inversely with complement levels (P < 0.001 in all). Titers of anti-dsDNA and anti-C1q, but not antinucleosome, correlated significantly with the renal SLEDAI score. The sensitivity of anti-dsDNA, antinucleosome, and anti-C1q for detecting the presence of active renal disease was 75%, 47%, and 53%, respectively. Anti-C1q had the highest specificity for active lupus renal disease (84%) followed by antinucleosome (57%) and the anti-dsDNA antibody (49%). The negative predictive value (NPV) of a negative anti-dsDNA and anti-C1q for active renal disease was 91%. For concurrent extrarenal SLE activity, the specificity was also highest with anti-C1q (83%). We conclude that antinucleosome does not perform better than anti-dsDNA for detecting concurrent SLE activity. The anti-C1q antibody, however, is more specific than anti-dsDNA for both active renal and extrarenal lupus. The absence of both anti-dsDNA and anti-C1q has a high NPV for renal activity.
authors.affiliation: Department of Medicine, Tuen Mun Hospital, Tsing Chung Koon Road, New Territories, Hong Kong, SAR China. ccmok2005@yahoo.com
authors.forename: Chi Chiu
authors.initials: CC
authors.lastname: Mok
authors.forename: Ling Yin
authors.initials: LY
authors.lastname: Ho
authors.forename: Hoi Wah
authors.initials: HW
authors.lastname: Leung
authors.forename: Lap Gate
authors.initials: LG
authors.lastname: Wong
mesh_terms: D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood / Q000276:immunology; D015922:Complement C1q / Q000276:immunology*; D003430:Cross-Sectional Studies; D004247:DNA / Q000276:immunology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007674:Kidney Diseases / Q000150:complications* / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000150:complications* / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity
chemical_list: D000974:Antibodies, Antinuclear; D007074:Immunoglobulin G; D015922:Complement C1q; D004247:DNA