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Table 4 Baseline predictors of ASAS20 response at six months of anti-TNF-α treatment

From: Baseline predictors of response and discontinuation of tumor necrosis factor-alpha blocking therapy in ankylosing spondylitis: a prospective longitudinal observational cohort study

   Univariate analysis Multivariate analysis
   OR (95% CI) P-value OR (95% CI) P-value
Age (yr)†a   0.977 (0.954 to 1.002) 0.069 0.960 (0.934 to 0.987) 0.004
Gender Female 1 -   -
  Male 1.995 (1.087 to 3.659) 0.026 2.991 (1.519 to 5.890) 0.002
Duration of symptoms (yr)†   0.997 (0.972 to 1.023) 0.821   ***
HLA-B27 Negative 1 -   -
  Positive 1.086 (0.520 to 2.266) 0.827   ***
Peripheral arthritis Absent 1 -   -
  Present 2.218 (0.952 to 5.165) 0.065   *
BASDAI (range 0 to 10)‡   1.031 (0.873 to 1.219) 0.717   ***
ASDAS‡   1.356 (0.945 to 1.946) 0.099 1.573 (1.051 to 2.354) 0.028
Physician's GDA (range 0 to 10)‡   1.087 (0.955 to 1.239) 0.207   **
Patient's GDA (range 0 to 10)‡a   1.124 (0.973 to 1.300) 0.113   *
ESR (mm/h)‡a   1.005 (0.991 to 1.019) 0.499   **
CRP (mg/l)‡   1.009 (0.993 to 1.024) 0.281   **
BASFI (range 0 to 10)‡   0.989 (0.861 to 1.135) 0.872   ***
Chest expansion (cm)‡a   1.108 (0.953 to 1.289) 0.183   **
Modified Schober test (cm)‡   0.900 (0.755 to 1.074) 0.243   **
Occiput to wall distance (cm)‡a   0.989 (0.950 to 1.030) 0.591   **
Lateral lumbar flexion L (cm)‡   0.985 (0.928 to 1.044) 0.606   ***
Lateral lumbar flexion R (cm)‡   1.018 (0.960 to 1.079) 0.557   ***
TNF-α blocking agent ETA 1 -   -
  IFX 1.279 (0.544 to 3.008) 0.573   **
  ADA 0.546 (0.278 to 1.076) 0.079   **
  1. See Table 1 for definitions.
  2. OR refers to the risk of achieving ASAS20 response: † per year; ‡ per 1 grade or 1 point.
  3. a Significant difference (P < 0.05) between men and women at baseline.
  4. * Presence of peripheral arthritis and patient's GDA were not selected during forward conditional logistic regression due to the significant difference in ASDAS score between patients with and without peripheral arthritis (mean 4.2 vs. 3.7, P = 0.001) and the strong correlation between ASDAS and patient's GDA (ρ = 0.508, P = 0.000). Although, presence of peripheral arthritis (OR: 2.518, 95% CI: 1.053 to 6.025) and higher patient's GDA (OR: 1.173, 95% CI: 1.003 to 1.372) were also significant predictors of ASAS20 response at 6 months in the presence of age and gender.
  5. ** The variable was not selected during multivariate regression analysis (P ≥0.05).
  6. *** The variable was not tested in multivariate regression analysis because of a P-value > 0.3 in univariate regression analysis and no significant difference between men and women at baseline.