Two-way analysis to test the association between MRI vertebral unit activity and syndesmophyte formation/growth after 2 years' follow-up*
| New syndesmophytes (R1 or R2) | New syndesmophytes (R1 and R2) | Growth of syndesmophytes (R1 or R2) | Growth of syndesmophytes (R1 and R2) | |||||
|---|---|---|---|---|---|---|---|---|
| Yes, N (%) | No, N (%) | Yes, N (%) | No, N (%) | Yes, N (%) | No, N (%) | Yes, N (%) | No, N (%) | |
| MRI reader 1: | ||||||||
| Active vertebral unit at BL | 36 (10.9/24.2) | 295 (89.1/16.1) | 12 (3.6/27.9) | 323 (96.4/16.2) | 4 (1.2/15.4) | 327 (98.8/16.7) | 1 (0.3/14.3) | 334 (99.7/16.4) |
| Inactive vertebral unit at BL | 113 (6.8/75.8) | 1537 (93.2/83.9) | 31 (1.8/72.1) | 1677 (98.2/83.9) | 22 (1.3/84.6) | 1627 (98.7/83.3) | 6 (0.4/85.7) | 1703 (99.6/83.6) |
| OR (95% CI) | 1.66 (1.12 to 2.47) | 2.01 (1.02 to 3.96) | 0.91 (0.31 to 2.64) | 0.85 (0.10 to 7.08) | ||||
| MRI reader 2: | ||||||||
| Active vertebral unit at BL | 36 (12.1/23.8) | 261 (87.9/14.1) | 10 (3.3/22.7) | 294 (96.7/14.5) | 6 (2.0/22.2) | 291 (98.0/14.7) | 2 (0.7/28.6) | 302 (99.3/14.6) |
| Inactive vertebral unit at BL | 115 (6.7/76.2) | 1592 (93.3/85.9) | 34 (1.9/77.3) | 1731 (98.1/85.5) | 21 (1.2/77.8) | 1685 (98.8/85.3) | 5 (0.3/71.4) | 1761 (99.7/85.4) |
| OR (95% CI) | 1.91 (1.28 to 2.84) | 1.73 (0.85 to 3.54) | 1.65 (0.66 to 4.13) | 2.33 (0.45 to 12.08) | ||||
| MRI reader 1: | ||||||||
| Active vertebral unit at BL only | 27 (11.4/18.1) | 209 (88.6/11.4) | 9 (3.8/20.9) | 229 (96.2/11.5) | 2 (0.8/7.7) | 234 (99.2/12.0) | 1 (0.4/14.3) | 237 (99.6/11.6) |
| Inactive vertebral unit at BL, or active at BL and other TP | 122 (7.0/81.9) | 1623 (93.0/88.6) | 34 (1.9/79.1) | 1771 (98.1/88.6) | 24 (1.4/92.3) | 1720 (98.6/88.0) | 6 (0.3/85.7) | 1800 (99.7/88.4) |
| OR (95% CI) | 1.72 (1.11 to 2.67) | 2.05 (0.97 to 4.32) | 0.61 (0.14 to 2.61) | 1.27 (0.15 to 10.6) | ||||
| MRI reader 2: | ||||||||
| Active vertebral unit at BL only | 22 (11.3/14.6) | 173 (88.7/9.3) | 7 (3.5/15.9) | 191 (96.5/9.4) | 4 (2.1/14.8) | 191 (97.9/9.7) | 2 (1.0/28.6) | 196 (99.0/9.5) |
| Inactive vertebral unit at BL, or active at BL and other TP | 129 (7.1/85.4) | 1680 (92.9/90.7) | 37 (2.0/84.1) | 1834 (98.0/90.6) | 23 (1.3/85.2) | 1785 (98.7/90.3) | 5 (0.3/71.4) | 1867 (99.7/90.5) |
| OR (95% CI) | 1.66 (1.03 to 2.67) | 1.82 (0.80 to 4.13) | 1.63 (0.56 to 4.75) | 3.81 (0.73 to 19.8) | ||||
| MRI reader 1: | ||||||||
| Active vertebral unit at BL and another TP | 9 (10.8/6.0) | 74 (89.2/4.1) | 3 (3.5/7.0) | 82 (96.5/4.1) | 2 (2.4/7.7) | 81 (97.6/4.2) | 0 (0.0/0.0) | 85 (100/4.2) |
| Inactive vertebral unit at BL, or active at BL but not at other TP | 140 (7.4/94.0) | 1746 (92.6/95.9) | 40 (2.1/93.0) | 1906 (97.9/95.9) | 24 (1.3/92.3) | 1861 (98.7/95.8) | 7 (0.4/100) | 1940 (99.6/95.8) |
| OR (95% CI) | 1.52 (0.74 to 3.09) | 1.74 (0.53 to 5.75) | 1.92 (0.45 to 8.24) | NA (p=0.580) | ||||
| MRI reader 2: | ||||||||
| Active vertebral unit at BL and another TP | 14 (14.3/9.3) | 84 (85.7/4.5) | 3 (2.9/6.8) | 99 (97.1/4.9) | 2 (2.0/7.4) | 96 (98.0/4.9) | 0 (0.0/0.0) | 102 (100/5.0) |
| Inactive vertebral unit at BL, or active at BL but not at other TP | 137 (7.2/90.7) | 1765 (92.8/95.5) | 41 (2.1/93.2) | 1922 (97.9/95.1) | 25 (1.3/92.6) | 1876 (98.7/95.1) | 7 (0.4/100) | 1957 (99.6/95.0) |
| OR (95% CI) | 2.15 (1.19 to 3.89) | 1.42 (0.43 to 4.67) | 1.56 (0.37 to 6.70) | NA (p=0.546) | ||||
| MRI reader 1: | ||||||||
| Active vertebral unit at any TP | 40 (11.2/28.6) | 318 (88.8/18.7) | 12 (3.3/31.6) | 349 (96.7/18.8) | 5 (1.4/21.7) | 352 (98.6/19.4) | 1 (0.3/16.7) | 361 (99.7/19.1) |
| Always inactive vertebral unit | 100 (6.7/71.4) | 1385 (93.3/81.3) | 26 (1.7/68.4) | 1511 (98.3/81.2) | 18 (1.2/78.3) | 1467 (98.8/80.6) | 5 (0.3/83.3) | 1532 (99.7/80.9) |
| OR (95% CI) | 1.74 (1.18 to 2.56) | 2.00 (1.00 to 4.00) | 1.16 (0.43 to 3.14) | 0.85 (0.10 to 7.29) | ||||
| MRI reader 2: | ||||||||
| Active vertebral unit at any TP | 40 (11.9/26.8) | 297 (88.1/16.7) | 10 (2.9/23.3) | 334 (97.1/17.2) | 8 (2.4/29.6) | 329 (97.6/17.4) | 2 (0.6/28.6) | 342 (99.4/17.3) |
| Always inactive vertebral unit | 109 (6.9/73.2) | 1477 (6.9/73.2) | 33 (2.0/76.7) | 1607 (98.0/82.8) | 19 (1.2/70.4) | 1566 (98.8/82.6) | 5 (0.3/71.4) | 1636 (99.7/82.7) |
| OR (95% CI) | 1.83 (1.24 to 2.68) | 1.46 (0.71 to 2.99) | 2.00 (0.87 to 4.62) | 1.91 (0.37 to 9.90) | ||||
| MRI reader 1: | ||||||||
| Always active vertebral unit | 0 (0.0/0.0) | 8 (100/0.5) | 0 (0.0/0.0) | 8 (100/0.4) | 0 (0.0/0.0) | 8 (100/0.4) | 0 (0.0/0.0) | 8 (100/0.4) |
| Not-always active vertebral unit | 140 (7.7/100) | 1679 (92.3/99.5) | 38 (2.0/100) | 1836 (98.0/99.6) | 23 (1.3/100) | 1795 (98.7/99.6) | 6 (0.3/100) | 1869 (99.7/99.6) |
| OR (95% CI) | NA (p=0.414) | NA (p=0.684) | NA (p=0.749) | NA (p=0.873) | ||||
| MRI reader 2: | ||||||||
| Always active vertebral unit | 0 (0.0/0.0) | 6 (100/0.3) | 0 (0.0/0.0) | 6 (100/0.3) | 0 (0.0/0.0) | 6 (100/0.3) | 0 (0.0/0.0) | 6 (100/0.3) |
| Not-always active vertebral unit | 149 (7.8/100) | 1763 (92.2/99.7) | 43 (2.2/100) | 1930 (97.8/99.7) | 27 (1.4/100) | 1884 (98.6/99.7) | 7 (0.4/100) | 1967 (99.6/99.7) |
| OR (95% CI) | NA (p=0.476) | NA (p=0.715) | NA (p= 0.769) | NA (p=0.884) | ||||
↵* In the table cells, the first percentage uses MRI activity as denominator, while the second percentage (in italic) uses syndesmophyte formation/growth as denominator. Statistically significant OR at the 5% level are highlighted in bold. For cases in which the cell count is 0, the OR could not be calculated and the p value of the Pearson χ2 result is provided.
BL, baseline; NA, not applicable; R1/R2, reader 1/reader 2; TP, time point.