Table 2.
The intrarater agreement
| Variable | Mean difference between the 2 readings (95% CI) | p-value* | ICC† (95% CI) | SEM (95% CI) | CR |
|---|---|---|---|---|---|
| SS | |||||
| Reader 1 | -0.88 (-1.76 to 0.00) | 0.051 | 0.96 (0.92–0.97) | 2.2 (1.9–2.8) | 6 |
| Reader 2 | -0.63 (-1.82 to 0.56) | 0.29 | 0.93 (0.88–0.96) | 2.9 (2.4–3.6) | 8 |
| Reader 3 | -0.51 (-1.68 to 0.66) | 0.39 | 0.92 (0.86–0.95) | 2.9 (2.4–3.6) | 8 |
| PI | |||||
| Reader 1 | -0.57 (-1.56 to 0.42) | 0.25 | 0.96 (0.94–0.98) | 2.4 (2.0–3.0) | 7 |
| Reader 2 | 0.69 (-1.22 to 2.61) | 0.47 | 0.89 (0.81–0.93) | 4.7 (3.9–5.8) | 13 |
| Reader 3 | -0.20 (-1.95 to 1.55) | 0.82 | 0.87 (0.79–0.93) | 4.3 (3.6–5.3) | 12 |
| TK | |||||
| Reader 1 | -0.57 (-1.84 to 0.70) | 0.37 | 0.93 (0.87–0.96) | 3.1 (2.6–3.9) | 9 |
| Reader 2 | 1.12 (-0.36 to 2.60) | 0.13 | 0.90 (0.83–0.94) | 3.7 (3.1–4.6) | 10 |
| Reader 3 | 0.67 (-1.34 to 2.69) | 0.50 | 0.82 (0.70–0.89) | 4.9 (4.1–6.2) | 14 |
| SVA | |||||
| Reader 1 | -0.39 (-1.16 to 0.43) | 0.37 | 0.99 (0.99–1.00) | 2.2 (1.8–2.7) | 6 |
| Reader 2 | 0.06 (-0.89 to 0.98) | 0.91 | 0.99 (0.99–1.00) | 2.6 (2.2–3.2) | 7 |
| Reader 3 | 0.63 (-1.72 to 2.99) | 0.64 | 0.99 (0.98–0.99) | 5.8 (4.8–7.2) | 16 |
| PT | |||||
| Reader 1 | 0.16 (-0.18 to 0.50) | 0.34 | 0.99 (0.98–1.00) | 0.8 (0.7–1.0) | 2 |
| Reader 2 | 0.18 (-1.09 to 1.46) | 0.77 | 0.86 (0.77–0.92) | 3.1 (2.6–3.9) | 9 |
| Reader 3 | 0.51 (-0.38 to 1.40) | 0.26 | 0.93 (0.88–0.96) | 2.2 (1.8–2.7) | 6 |
CI, confidence interval; ICC, intraclass correlation coefficient; SEM, standard error of measurement; CR, coefficient of repeatability; SS, sacral slope; PI, pelvic incidence; TK, thoracic kyphosis T4–T12; SVA, sagittal vertical axis; PT, pelvic tilt.
*
t-test for paired samples.
†
ICC calculated using the 1-way-random effects model.