Table 2.
Predictors of sustained low BASFI (< 3) between 12 and 18 months
| Parameter | Univariable analysis | Multivariable analysis 1a (N = 417) | Multivariable analysis 2 (N = 417) | |||
|---|---|---|---|---|---|---|
| OR (95% CI) | P-value | OR (95% CI) | P-value | OR (95% CI) | P-value | |
| Age, years | 0.96 (0.95, 0.98) | < 0.001 | - | - | - | - |
| Disease duration, years | 1.0 (0.98, 1.01) | 0.335 | - | - | - | - |
| Gender, male vs female | 1.3 (1.0, 1.9) | 0.087 | - | - | - | - |
| Smoking | 0.8 (0.5, 1.2) | 0.230 | - | - | - | - |
| Enrollment period | 0.411 | - | - | - | - | |
| 2006–2008 vs. 2016–2017 | 0.7 (0.4, 1.2) | |||||
| 2009–2012 vs. 2016–2017 | 0.8 (0.4, 1.4) | |||||
| 2013–2015 vs. 2016–2017 | 1.0 (0.6, 1.6) | |||||
| Biologic naïve | 1.0 (0.6, 1.6) | 0.956 | - | - | - | - |
| Baseline nbDMARD use | 0.9 (0.6, 1.3) | 0.530 | - | - | - | - |
| Baseline NSAID use | 1.1 (0.8, 1.6) | 0.592 | - | - | - | - |
| Baseline steroid use | 1.2 (0.6, 2.3) | 0.606 | - | - | - | - |
| Anti-TNF, golimumab vs. infliximab | 1.6 (1.1, 2.2) | 0.007 | - | - | - | - |
| Baseline enthesitis | 0.9 (0.5, 1.4) | 0.553 | - | - | - | - |
| Baseline dactylitis | 1.0 (0.4, 2.4) | 0.967 | - | - | - | - |
| Baseline CRP, mg/L | 1.0 (0.99, 1.01) | 0.257 | - | - | - | - |
| Baseline ASDAS | 0.6 (0.5, 0.8) | < 0.001 | - | - | - | - |
| Baseline BASDAI | 0.7 (0.65, 0.8) | < 0.001 | - | - | - | - |
| BASFI, baseline | 0.66 (0.6, 0.7) | < 0.001 | 0.7 (0.6, 0.8) | < 0.001 | 0.7 (0.6, 0.8) | < 0.001 |
| Low BASDAI < 3 | ||||||
| M6 and M12 vs. persistent BASDAI ≥ 3 | 37.3 (21.4, 64.9) | < 0.001 | 10.5 (4.0, 27.2) | < 0.001 | 7.4 (3.1, 17.7) | < 0.001 |
| M6 or M12 vs. persistent BASDAI ≥ 3 | 5.5 (3.3, 4.4) | < 0.001 | 5.2 (2.4, 11.1) | < 0.001 | 4.0 (1.8, 8.7) | 0.001 |
| ASDAS-ID (< 1.3) | ||||||
| M6 and M12 vs. persistent ASDAS ≥ 1.3 | 25.3 (9.2, 69.8) | < 0.001 | 3.7 (1.1, 13.1) | 0.040 | N/A | N/A |
| M6 or M12 vs. persistent ASDAS ≥ 1.3 | 8.5 (3.8, 18.9) | < 0.001 | 2.2 (0.8, 6.0) | 0.144 | N/A | N/A |
| ASDAS-LDA (< 2.1) | ||||||
| M6 and M12 vs. persistent ASDAS ≥ 2.1 | 31.9 (14.6, 70.1) | < 0.001 | N/A | N/A | 7.2 (2.7, 19.3) | < 0.001 |
| M6 or M12 vs. persistent ASDAS ≥ 2.1 | 3.8 (2.0, 7.1) | < 0.001 | N/A | N/A | 2.1 (1.0, 4.2) | 0.053 |
BASFI Bath Ankylosing Spondylitis Functional Index; GEE generalized estimating equation; OR odds ratio; CI confidence interval; M month; BASDAI Bath Ankylosing Spondylitis Disease Activity Index; ASDAS Ankylosing Spondylitis Disease Activity Score; ID inactive disease; LDA low disease activity
aPredictors retained following backward stepwise selection of parameters showing a P < 0.1 in univariable analysis. ASDAS-ID was forced into the model even though it was not retained. Bold P-values denote statistical significance
Multivariable analysis 1: primary analysis; multivariable analysis 2: secondary analysis including ASDAS-LDA instead of ASDAS-ID