Cohen’s kappa-test comparison among four methods for ANAs detection
| Autoantibody* | Observed agreements (%) | Kappa value† | 95% CI | Level of agreement‡ |
| Comparison of ELISA versus ANA-LIA Maxx | ||||
| dsDNA | 68.57 | 0.427 | 0.285 to 0.568 | Weak |
| Ro | 91.11 | 0.833 | 0.730 to 0.937 | Strong |
| La | 93.15 | 0.688 | 0.448 to 0.928 | Moderate |
| Sm | 81.43 | 0.476 | 0.238 to 0.713 | Weak |
| RNP | 69.57 | 0.379 | 0.193 to 0.565 | Minimal |
| Comparison of ELISA versus ANA-Profile 23 | ||||
| dsDNA | 57.78 | 0.150 | −0.040 to 0.340 | None |
| Ro | 86.67 | 0.740 | 0.606 to 0.873 | Moderate |
| La | 88.89 | 0.621 | 0.420 to 0.821 | Moderate |
| Sm | 92.22 | 0.500 | 0.189 to 0.811 | Weak |
| RNP | 82.02 | 0.489 | 0.294 to 0.684 | Weak |
| Comparison of ELISA versus ImmcoStripe ANA Advanced LIA | ||||
| dsDNA | 56.67 | 0.196 | 0.019 to 0.372 | None |
| Ro | 70.00 | 0.412 | 0.230 to 0.593 | Weak |
| La | 78.89 | 0.495 | 0.310 to 0.679 | Weak |
| Sm | 88.89 | 0.589 | 0.368 to 0.810 | Weak |
| RNP | 51.11 | 0.153 | −0.001 to 0.307 | None |
| Comparison of ANA-LIA Maxx versus ANA-Profile 23 | ||||
| dsDNA | 61.11 | 0.222 | 0.042 to 0.402 | Minimal |
| Ro | 83.33 | 0.696 | 0.567 to 0.827 | Moderate |
| La | 83.33 | 0.508 | 0.313 to 0.703 | Weak |
| Sm | 82.22 | 0.279 | 0.050 to 0.508 | Minimal |
| RNP | 78.89 | 0.323 | 0.098 to 0.548 | Minimal |
| Nucleosome | 77.78 | 0.138 | −0.092 to 0.368 | None |
| Histone | 84.44 | 0.197 | −0.051 to 0.445 | None |
| Mi-2 | 83.33 | 0.051 | −0.166 to 0.2.68 | None |
| Comparison of ANA-LIA Maxx versus ImmcoStripe ANA Advanced LIA | ||||
| dsDNA | 60.00 | 0.280 | 0.121 to 0.439 | Minimal |
| Ro | 66.67 | 0.377 | 0.207 to 0.546 | Minimal |
| La | 74.44 | 0.431 | 0.254 to 0.607 | Weak |
| Sm | 81.11 | 0.441 | 0.225 to 0.695 | Weak |
| RNP | 50.00 | 0.177 | 0.054 to 0.30 | None |
| Nucleosome | 33.33 | 0.060 | −0.002 to 0.122 | None |
| Histone | 68.89 | 0.275 | 0.122 to 0.427 | Minimal |
| Mi-2 | 70.00 | 0.140 | −0.021 to 0.30 | None |
| Comparison of Ana-Profile23 versus ImmcoStripe ANA Advanced LIA | ||||
| dsDNA | 53.33 | 0.160 | −0.012 to 0.33 | None |
| Ro | 70.00 | 0.430 | 0.260 to 0.601 | Weak |
| La | 76.67 | 0.403 | 0.224 to 0.583 | Weak |
| Sm | 83.33 | 0.296 | 0.058 to 0.534 | Minimal |
| RNP | 38.99 | 0.000 | −0.089 to 0.089 | None |
| Nucleosome | 33.33 | 0.025 | −0.057 to 0.107 | None |
| Histone | 63.33 | 0.097 | −0.031 to 0.225 | None |
| Mi-2 | 63.33 | 0.030 | −0.150 to 0.089 | None |
*The following autoantibodies were evaluated by ELISA commercially obtained from Inova Diagnostics, San Diego, California, USA: anti-dsDNA, anti-RNP, anti-Ro, anti-La, and anti-Sm. ELISAs were performed as specified by the manufacturer and included both positive and negative controls assayed in parallel. Simultaneously, sera were assessed by three line immunoassays from different biotechnology companies: IMTEC-ANA-LIA Maxx (Human diagnostics, Magdeburg Germany), ANA-Profile 23 (Euroimmune, Luebeck, Germany) and ImmcoStripe ANA Advanced LIA (Trinity Biotech, Bray, Co. Wicklow, Ireland).
†The interassay agreement was assessed by the Cohen’s Kappa test implemented in Graph Pad calculator (https://www.graphpad.com/quickcalcs/kappa1.cfm).
‡Interpretation of the values was done as suggested by McHugh.7
dsDNA: double-strand DNA; RNP: ribonucleoprotein; Sm: Smith.