Comparison of the burden of disease between r-axSpA and nr-axSpA: pooled analysis
| Continuous variables | ||||||||
| Variable | N studies | r-axSpA | nr-axSpA | SMD (95% CI) | P value | I2 | ||
| N patients | Pooled mean (95% CI) | N patients | Pooled mean (95% CI) | |||||
| BASDAI | 39 | 7823 | 4.6 (4.3 to 4.9) | 3890 | 4.6 (4.3 to 5.0) | −0.04 (−0.08 to 0.01) | 0.101 | 19.9% |
| BASDAI Q3 (joint pain) | 2 | 643 | 3.0 (2.8 to 3.2) | 97 | 2.9 (2.4 to 3.4) | 0.05 (0.18 to 0.27) | 0.688 | 0.0% |
| BASDAI Q4 (enthesis pain) | 2 | 643 | 3.4 (2.5 to 4.4) | 97 | 3.3 (2.5 to 4.0) | 0.02 (0.21 to 0.24) | 0.874 | 0.0% |
| CRP (mg/dL) | 36 | 7420 | 9.3 (8.0 to 10.6) | 3731 | 6.2 (5.2 to 7.3) | 0.30 (0.20 to 0.39) | <0.001 | 79.3% |
| ESR (mm/h) | 24 | 5236 | 24.4 (21.1 to 27.6) | 2601 | 20.4 (14.3 to 26.5) | 0.24 (0.15 to 0.33) | <0.001 | 65.1% |
| ASDAS-CRP | 18 | 3039 | 2.7 (2.4 to 3.0) | 1895 | 2.6 (2.4 to 2.8) | 0.11 (0.00 to 0.21) | 0.042 | 57.1% |
| VAS back pain | 8 | 2195 | 5.1 (4.1 to 6.1) | 772 | 5.1 (4.1 to 6.2) | −0.12 (−0.21 to −0.03) | 0.007 | 40.6% |
| VAS pain | 10 | 1994 | 4.9 (4.4 to 5.5) | 1042 | 4.7 (4.2 to 5.2) | 0.02 (−0.06 to 0.10) | 0.618 | 20.9% |
| Patient Global Assessment | 16 | 3506 | 5.3 (4.8 to 5.7) | 1761 | 5.1 (4.6 to 5.7) | −0.01 (−0.07 to 0.05) | 0.838 | 44.2% |
| Physician Global Assessment | 12 | 3130 | 3.9 (3.2 to 4.7) | 1919 | 3.7 (2.9 to 4.5) | 0.13 (0.0 to 0.25) | 0.030 | 63.6% |
| BASFI | 35 | 6901 | 3.4 (3.2 to 3.7) | 3506 | 3.0 (2.7 to 3.3) | 0.19 (0.12 to 0.26) | <0.001 | 50.3% |
| HAQ-S | 4 | 1405 | 0.6 (0.51 to 0.76) | 413 | 0.6 (0.5 to 0.7) | 0.06 (−0.05 to 0.17) | 0.296 | 0.0% |
| ASQoL | 10 | 2738 | 7.3 (6.7 to 7.9) | 1082 | 6.9 (5.4 to 8.3) | 0.09 (0.01 to 0.17) | 0.035 | 30.0% |
| SF-36 mental component | 7 | 2045 | 48.5 (46.5 to 50.6) | 636 | 48.2 (44.1 to 52.3) | 0.03 (−0.06 to 0.11) | 0.518 | 9.4% |
| SF-36 physical component | 6 | 1207 | 40.6 (37.0 to 44.3) | 404 | 42.0 (37.2 to 46.7) | −0.05 (−0.15 to 0.06) | 0.406 | 0.0% |
| EQ-5D | 4 | 1802 | 0.7 (0.6 to 0.8) | 322 | 0.6 (0.4 to 0.8) | 0.02 (−0.12 to 0.16) | 0.784 | 0.0% |
| HADS-anxiety | 2 | 480 | 7.4 (7.0 to 7.8) | 250 | 7.1 (6.6 to 7.7) | 0.08 (−0.17 to 0.33) | 0.529 | 51.9% |
| HADS-depression | 2 | 480 | 7.2 (6.3 to 8.2) | 250 | 6.3 (5.8 to 6.8) | 0.17 (0.01 to 0.02) | 0.034 | 0.0% |
| BASMI | 14 | 4800 | 2.8 (2.2 to 3.2) | 2089 | 1.6 (1.3 to 1.9) | 0.69 (0.46 to 0.91) | <0.001 | 93.4% |
| Categorical variables | ||||||||
| Variable | N studies | r-axSpA | nr-axSpA | RR (95% CI) | P value | I2 | ||
| N patients | Pooled percentage (95% CI) | N patients | Pooled percentage (95% CI) | |||||
| CRP >5 mg/L | 5 | 1922 | 45.4 (34.9 to 56.3) | 1009 | 35.6 (27.5 to 44.7) | 1.27 (1.16 to 1.38) | <0.001 | 49.4% |
ASDAS-CRP, Ankylosing Spondylitis Disease Activity Score; ASQoL, Ankylosing Spondylitis Quality of Life; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Disease Functional index; BASMI, Bath Ankylosing Spondylitis Metrology Index; CRP, C-reactive protein; EQ-5D, EuroQoL questionnaire; ESR, erythrocyte sedimentation rate; HADS, Hospital Anxiety and Depression Scale; HAQ-S, Health Assessment Questionnaire for spondyloarthropathies; nr-axSpA, non-radiographic axial Spondyloarthritis; r-axSpA, radiographic axial Spondyloarthritis; RR, relative risk; SMD, standardised means difference; VAS, visual analogue scale.