Article Figures & Data
Figures
- Figure 1.
Anti-dsDNA in patients with SLE and control groups as measured by CLIFT (A), FIDIS (B), EliA (C), and EUROLINE (D). SLE disease specificity of different anti-dsDNA antibody assays was calculated in relation to control groups (RA, pSS, and HC). The dashed lines indicate cutoff for positivity according to laboratory reference (A), manufacturer’s recommendation (lower line in panel B–D), or double manufacturers’ references (upper line in panel B–D). Specificity and sensitivity for the respective cutoff limits are denoted in the tables above the graphs. SLE: systemic lupus erythematosus; CLIFT: Crithidia luciliae immunofluorescence test; FIDIS: bead-based multiplex assay; EliA: fluoroenzyme-immunoassay; EUROLINE: line blot; RA: rheumatoid arthritis; pSS: primary Sjögren syndrome; HC: healthy controls; N/A: not applicable.
- Figure 2.
Correlation and concordance of anti-dsDNA assays in cross-sectional SLE samples. Panels (A–F) are sorted according to correlation. Certain dots represent more than 1 patient. Zero values are replaced with 1 for CLIFT and 0.5 for EUROLINE, to be contained in the log-scale of the axes. Dashed lines indicate the manufacturer’s cutoff for positivity (EliA, FIDIS, and EUROLINE) or laboratory reference (CLIFT), and numbers designate the sum of patients in the specific quadrant. Values of p and rho are from Spearman correlation. Values below cutoff were given a value of 0 to avoid unwanted influence of double-negative samples in the correlation analyses. The rho values and assay concordances when adopting a cutoff limit double the manufacturer’s recommendation are given in parentheses. Concordance is the sum of double-positive samples and double-negative samples, divided by the total number of patients (n = 178). SLE: systemic lupus erythematosus; CLIFT: Crithidia luciliae immunofluorescence test; EUROLINE: line blot; EliA: fluoroenzyme-immunoassay; FIDIS: bead-based multiplex assay.
- Figure 3.
The graphs illustrate disease activity (PGA and SLEDAI-2K*), manifestations at flare, and anti-dsDNA levels in 9 patients (A–I) who were followed consecutively. Description of axes and lines are found in panel A. Axes scales are different among the graphs. Disease flare manifestations of patients with several flares were serositis and arthritis at first flare, and serositis at second flare (B); rash, nephritis, and fever at first flare, and rash, nephritis, and vasculitis at second flare (E); serositis and leukopenia at first flare, and nephritis at second flare (F); serositis and nephritis at first flare, and nephritis at second flare (G); epilepsy and serositis at first flare, and arthritis, rash, and epilepsy at second flare, and rash, alopecia, and epilepsy at third flare, and rash, alopecia, oral ulcers, and epilepsy at fourth flare (H). * Item for anti-dsDNA in SLEDAI was excluded. PGA: physician global assessment; SLEDAI-2K: Systemic Lupus Erythematosus Disease Activity Index 2000; EliA: fluoroenzyme-immunoassay; FIDIS: bead-based multiplex assay; CLIFT: Crithidia luciliae immunofluorescence test.
Tables
- Table 1.
Association of SLE disease criteria and anti-dsDNA assessed by 4 different assays. The analysis (Fisher’s exact test) is not adjusted for multiple comparisons.
Cumulative ACR-82 Criteria* (% fulfilling the criterion) FIDIS EliA CLIFT EUROLINE p OR (95% CI) p OR (95% CI) p OR (95% CI) p OR (95% CI) 1. Malar rash (45%) 0.325 1.41 (0.74–2.69) 0.753 1.12 (0.60–2.08) 0.726 0.84 (0.42–1.70) 0.870 1.08 (0.57–2.05) 2. Discoid rash (17%) 0.084 0.40 (0.14–1.10) 0.302 0.60 (0.25–1.43) 0.356 0.55 (0.20–1.54) 0.391 0.62 (0.25–1.54) 3. Photosensitivity (56%) 0.047 0.49 (0.26–0.95) 0.752 0.86 (0.46–1.60) 0.003 0.33 (0.16–0.67) 0.104 0.58 (0.31–1.11) 4. Oral ulcers (10%) 0.587 1.32 (0.46–3.79) 0.035 3.00 (1.08–8.31) 0.249 1.83 (0.63–5.28) 0.405 1.70 (0.61–4.73) 5. Arthritis (78%) 0.692 0.81 (0.38–1.73) 0.447 0.71 (0.34–1.47) 0.674 1.30 (0.55–3.10) 1.0 0.97 (0.45–2.11) 6. Serositis (38%) 0.315 1.42 (0.73–2.72) 0.746 0.87 (0.46–1.65) 0.588 1.26 (0.63–2.55) 0.737 0.86 (0.44–1.67) 7. Renal disorder (21%) 0.01 2.70 (1.29–5.68) 0.004 2.98 (1.43–6.23) 0.054 2.23 (1.03–4.85) 0.171 1.69 (0.80–3.57) 8. Neurologic disorder (6%) 1.0 0.98 (0.25–3.98) 0.321 1.95 (0.54–7.00) 1.0 0.77 (0.15–3.79) 0.174 0.41 (0.11–1.49) 9. Hematologic disorder (57%) 0.013 2.42 (1.21–4.83) 0.525 1.28 (0.69–2.41) 0.480 1.35 (0.67–2.73) 0.621 1.23 (0.65–2.35) 1, 2, or 3. Skin (75%) 0.086 0.51 (0.25–1.04) 1.0 1.04 (0.51–2.14) 0.001 0.29 (0.14–0.60) 0.091 0.53 (0.26–1.08) -
Significant data are in bold face.
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↵* Immunologic disorder (ACR criterion 10, 49% of patients) and antinuclear antibodies (ACR criterion 11, 98% of patients) are not reported because all anti-dsDNA–positive patients by CLIFT fulfill these criteria. Manufacturer’s cutoff (FIDIS, EliA, and EUROLINE) or laboratory reference cutoff (CLIFT) for positivity were used. SLE: systemic lupus erythematosus; ACR-82: American College of Rheumatology 1982 criteria; FIDIS: bead-based multiplex assay; EliA: fluoroenzyme-immunoassay; CLIFT: Crithidia luciliae immunofluorescence test; EUROLINE: line blot.
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- Table 2.
Spearman correlation between disease variables and anti-dsDNA antibody levels assessed by 4 assays. Variables are organized according to correlation coefficient.
Variables FIDIS EliA CLIFT EUROLINE rho p rho p rho p rho p Classical complement function, n = 169 −0.552 < 0.0005 −0.426 < 0.0005 −0.333 < 0.0005 −0.195 0.011 C4, n = 177 −0.495 < 0.0005 −0.362 < 0.0005 −0.284 < 0.0005 −0.209 0.005 C3, n = 178 −0.371 < 0.0005 −0.251 0.001 −0.218 0.003 −0.154 0.040 IFN-α, n = 178 0.323 < 0.0005 0.269 < 0.0005 0.215 0.004 0.137 0.068 ESR, n = 178 0.193 0.010 0.176 0.019 0.112 0.135 0.081 0.280 SLEDAI-2K*, n = 178 0.148 0.048 0.121 0.109 0.096 0.203 0.034 0.657 PGA, n = 178 0.109 0.148 0.160 0.033 −0.001 0.984 0.012 0.876 -
↵* Item for anti-dsDNA (by CLIFT) excluded. FIDIS: bead-based multiplex assay; EliA: fluoroenzyme-immunoassay; CLIFT: Crithidia luciliae immunofluorescence test; EUROLINE: line blot; IFN-α: interferon-α; ESR: erythrocyte sedimentation rate; SLEDAI-2K: Systemic Lupus Erythematosus Disease Activity Index 2000; PGA: physician global assessment.
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