Table 4.
Bland–Altman and receiver operator analysis for quantitative data
| Leads | Mean | SD | CI upper limit | CI lower limit | Outliers (%) | AUC |
|---|---|---|---|---|---|---|
| Bias | ||||||
| PR interval (ms) | 0.76 | 12.00 | 24.28 | −22.76 | 13 (1.8) | 0.91 |
| QRS duration (ms) | 0.29 | 8.47 | 16.89 | −16.32 | 21 (2.4) | 0.98 |
| Axis | 4.24° | 22.11° | 47.57° | −39.08° | 34 (4.3) | 0.85 |
| QRS amplitude Lead I (mm) | −1.47 | 2.91 | 4.23 | −7.17 | 41 (4.2) | NA |
| QRS amplitude Lead II (mm) | 0.96 | 2.07 | 5.02 | −3.10 | 31 (3.1) | NA |
| QRS amplitude Lead III (mm) | −0.16 | 2.73 | 5.18 | −5.50 | 40 (4.1) | NA |
| QRS amplitude Lead AVR (mm) | −0.33 | 1.80 | 3.19 | −3.85 | 34 (3.4) | NA |
| QRS amplitude Lead AVL (mm) | −1.13 | 2.56 | 3.90 | −6.15 | 39 (4.0) | NA |
| QRS amplitude Lead AVF (mm) | 0.94 | 2.11 | 5.06 | −3.19 | 37 (3.7) | NA |
| QT Lead I (ms) | 6.29 | 21.68 | 48.69 | −36.21 | 29 (4.0) | 0.79 |
| QTc Lead I (ms) | −0.27 | 28.17 | 54.93 | −55.48 | 29 (4.0) | 0.70 |
| QT Lead II (ms) | 7.03 | 19.81 | 45.87 | −31.80 | 22 (3.0) | 0.82 |
| QTc Lead II (ms) | 0.62 | 26.82 | 53.19 | −51.95 | 37 (5.1) | 0.69 |
| QT Lead III (ms) | 6.47 | 23.99 | 53.48 | −40.54 | 19 (3.7) | 0.79 |
| QTc Lead III (ms) | 1.15 | 28.67 | 57.35 | −55.05 | 25 (4.9) | 0.66 |
| QT Lead AVR (ms) | 7.06 | 21.18 | 48.57 | −34.46 | 20 (2.8) | 0.81 |
| QTc Lead AVR (ms) | −0.03 | 27.11 | 53.10 | −53.15 | 37 (5.2) | 0.70 |
| QT Lead AVL (ms) | 5.45 | 22.50 | 49.56 | −38.65 | 21 (3.2) | 0.80 |
| QTc Lead AVL (ms) | −2.02 | 28.38 | 53.61 | −57.65 | 28 (4.2) | 0.67 |
| QT Lead AVF (ms) | 8.49 | 23.00 | 53.57 | −36.59 | 17 (3.0) | 0.77 |
| QTc Lead AVF (ms) | 2.35 | 29.14 | 59.46 | −54.76 | 31 (5.4) | 0.64 |
| Longest QT (ms) | 11.76 | 20.69 | 52.31 | −28.79 | 24 (3.2) | 0.80 |
| QTc longest (ms) | 5.71 | 27.11 | 58.85 | −47.42 | 43 (5.7) | 0.74 |
AUC, area under the curve (the normal range was set at a QT/QTc of between 360 and 460 ms; CI, 95% confidence interval for upper and lower limit on Bland–Altman analysis; outlier percentage compared to the number of ECGs analysed rather than total sample); SD, standard deviation; NA, not applicable.