Table 3:
Intraobserver, Interobserver and Scan-Rescan variability of per patient plaque volume measurements.
Intraobserver Variability | Observation 1 | Observation 2 | LCC (95% CI) | Mean difference | P value | Bland-Altman 95% LoA (95% CI) | CoR |
---|---|---|---|---|---|---|---|
Total Plaque (mm3) | 2063 ± 1246 [1443–2683] |
2077 ± 1260 [1450–2704] |
1.0 (1.0 – 1.0) |
14.1 | 0.29 | −93 (−155, −58) to +121 (87, 183) |
107.0 |
Non-calcified Plaque (mm3) | 1765 ± 910 [1312–2217] |
1780 ± 921 [1322–2238] |
1.0 (1.0 – 1.0) |
15.4 | 0.28 | −99 (−165, −62) to +129 (93, 196) |
114.1 |
Calcified Plaque (mm3) | 298 ± 425 [87–510] |
297 ± 425 [86–508] |
1.0 (1.0 – 1.0) |
−1.2 | 0.68 | −25 (−39, −17) to +23 (15, 36) |
23.7 |
Low-attenuation Plaque (mm3) | 13 ± 13 [7–20] |
12 ± 13 [5–18] |
0.97 (0.93 – 0.99) |
−1.6 | 0.02 | −7 (−9, −5) to +4 (1, 6) |
5.2 |
Interobserver Variability | Investigator 1 | Investigator 2 | LCC (95% CI) | Mean difference | P value | Bland-Altman 95% LoA (95% CI) | CoR |
Total Plaque (mm3) | 2063 ± 1246 [1443–2683] |
1985 ± 1161 [1443–2683] |
0.97 (0.93 – 0.99) |
−74.2 | 0.24 | −615 (−927, −442) to +459 (286, 770) |
537.0 |
Non-calcified Plaque (mm3) | 1765 ± 910 [1312–2217] |
1688 ± 803 [1289–2087] |
0.95 (0.88 – 0.98) |
−76.5 | 0.24 | −594 (−894, −428) to +441 (275, 742) |
517.6 |
Calcified Plaque (mm3) | 298 ± 425 [87–510] |
297 ± 432 [82–512] |
1.0 (0.99 – 1.0) |
−1.7 | 0.84 | −69 (−97, −41) to 66 (38, 94) |
67.5 |
Low-attenuation Plaque (mm3) | 13 ± 13 [7–20] |
14 ± 12 [8–20] |
0.90 (0.76 – 0.96) |
1.2 | 0.39 | −10 (−14, −5) to +12 (8, 17) |
11.0 |
Scan-Rescan Variability | Baseline Scan | Repeat Scan | LCC (95% CI) | Mean difference | P value | Bland-Altman 95% LoA (95% CI) | CoR |
Total Plaque (mm3) | 2063 ± 1246 [1443–2683] |
2027 ± 1223 [1419–2635] |
0.98 (0.94 – 0.99) |
−35.6 | 0.56 | −531 (−735, −328) to 460 (257, 664) |
495.7 |
Non-calcified Plaque (mm3) | 1765 ± 910 [1312–2217] |
1760 ± 928 [1299–2221] |
0.97 (0.93 – 0.99) |
−4.3 | 0.93 | −418 (−587, −248) to +409 (239, 579) |
413.4 |
Calcified Plaque (mm3) | 298 ± 425 [87–510] |
267 ±377 [79–455] |
0.96 (0.91 – 0.98) |
−31.3 | 0.22 | −237 (−321, −152) to +174 (90, 258) |
205.2 |
Low-attenuation Plaque (mm3) | 13 ± 13 [7–20] |
10 ±13 [4–17] |
0.85 (0.64 – 0.94) |
−2.6 | 0.11 | −16 (−21, −10) to +11 (5, 16) |
13.1 |
Mean ± standard deviation [95% confidence interval], LCCC – Lin’s concordance correlation coefficient (95% confidence interval), LoA – Limits of agreement (95% confidence interval), CoR - coefficient of repeatability.