Effects of disease activity on radiographic progression in subgroups*
| Subgroup† | Overall group | Men | Women | ||
|---|---|---|---|---|---|
| p Value for the interaction | 2-year increase in mSASSS per one-ASDAS unit increase (units, (95% CI)) | 2-year increase in mSASSS per one-ASDAS unit increase (units, (95% CI)) | 2-year increase in mSASSS per one-ASDAS unit increase (units, (95% CI)) | ||
| Smoking | Smokers (n=49) | <0.001 | 1.94 (1.00 to 2.87) | 2.15 (1.01 to 3.30) | 0.47 (−0.12 to 1.06) |
| Non-smokers (n=78) | 0.35 (0.04 to 0.65) | 0.44 (0.02 to 0.86) | 0.16 (−0.13 to 0.44) | ||
| Job type | ‘Blue collar’ (n=65) | 0.014 | 1.19 (0.58 to 1.79) | 1.47 (0.81 to 2.14) | −0.60 (−1.59 to 0.40) |
| ‘White collar’ (n=71) | 0.20 (−0.23 to 0.64) | 0.35 (−0.30 to 1.01) | −0.08 (−0.43 to 0.28) | ||
| Education | ‘Non-university’ (n=167) | 0.364 | 0.74 (0.41 to 1.07) | 1.00 (0.55 to 1.44) | −0.04 (−0.39 to 0.30) |
| ‘University’ (n=14) | −0.18 (−1.91 to 1.55) | 0.81 (−3.15 to 4.78) | −0.74 (−1.82 to 0.34) | ||
| Monthly gross personal income | <€1588 (n=105) | 0.059 | 0.93 (0.45 to 1.41) | 1.31 (0.66 to 1.96) | −0.20 (−0.66 to 0.25) |
| ≥€1588 (n=56) | 0.14 (−0.21 to 0.50) | 0.18 (−0.24 to 0.59) | −0.21 (−0.90 to 0.48) | ||
| Monthly gross family income | <€3176 (n=90) | 0.445 | 0.49 (0.09 to 0.89) | 0.77 (0.27 to 1.27) | −0.25 (−0.80 to 0.30) |
| ≥€3176 (n=21) | 0.15 (−0.35 to 0.65) | 0.36 (−0.22 to 0.94) | −0.15 (−0.93 to 0.63) | ||
*All models are time-lagged (2 years of time lag) and autoregressive (ie, adjusted for mSASSS in the 2-years before). Progression per subgroup is expressed in mSASSS units over 2 years per one-ASDAS unit increase.
†Subgroup analysis was conducted in all patients with the variable of each of the subgroup analyses available, which means that due to missing values some patients were not included in some of the subgroup analyses. Numbers of included patients can be seen in front of the corresponding stratum.
ASDAS, Ankylosing Spondylitis Disease Activity Score; mSASSS, modified Stoke Ankylosing Spondylitis Spine Score.